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Chapter 8
Remembering and Judging She Was Certain, but She Was Wrong
In 1984 Jennifer Thompson was a 22-year-old college student in North Carolina. One night a man broke into her
apartment, put a knife to her throat, and raped her. According to her own account, Ms. Thompson studied her rapist
throughout the incident with great determination to memorize his face. She said:
I studied every single detail on the rapist’s face. I looked at his hairline; I looked for scars, for tattoos, for
anything that would help me identify him. When and if I survived.
Ms. Thompson went to the police that same day to create a sketch of her attacker, relying on what she believed was
her detailed memory. Several days later, the police constructed a photographic lineup. Thompson identified Ronald
Cotton as the rapist, and she later testified against him at trial. She was positive it was him, with no doubt in her
mind.
I was sure. I knew it. I had picked the right guy, and he was going to go to jail. If there was the possibility of
a death sentence, I wanted him to die. I wanted to flip the switch.
As positive as she was, it turned out that Jennifer Thompson was wrong. But it was not until after Mr. Cotton had
served 11 years in prison for a crime he did not commit that conclusive DNA evidence indicated that Bobby Poole was
the actual rapist, and Cotton was released from jail. Jennifer Thompson’s memory had failed her, resulting in a
substantial injustice. It took definitive DNA testing to shake her confidence, but she now knows that despite her
confidence in her identification, it was wrong. Consumed by guilt, Thompson sought out Cotton when he was released
from prison, and they have since become friends (Innocence Project, n.d.; Thompson, 2000). [1]
Picking Cotton: A Memoir of Injustice and Redemption
Although Jennifer Thompson was positive that it was Ronald Cotton who had raped her, her memory was inaccurate.
Conclusive DNA testing later proved that he was not the attacker. Watch this book trailer about the story.
Jennifer Thompson is not the only person to have been fooled by her memory of events. Over the past 10 years,
almost 400 people have been released from prison when DNA evidence confirmed that they could not have
committed the crime for which they had been convicted. And in more than three-quarters of these cases, the cause of
the innocent people being falsely convicted was erroneous eyewitness testimony (Wells, Memon, & Penrod, 2006). [2]
Eyewitness Testimony
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Watch this video for Lesley Stahl’s 60 Minutes segment on this case.
The two subjects of this chapter are memory, defined as the ability to store and retrieve
information over time, and cognition, defined as the processes of acquiring and using knowledge.
It is useful to consider memory and cognition in the same chapter because they work together to
help us interpret and understand our environments.
Memory and cognition represent the two major interests of cognitive psychologists. The
cognitive approach became the most important school of psychology during the 1960s, and the
field of psychology has remained in large part cognitive since that time. The cognitive school
was influenced in large part by the development of the electronic computer, and although the
differences between computers and the human mind are vast, cognitive psychologists have used
the computer as a model for understanding the workings of the mind.
Differences between Brains and Computers
In computers, information can be accessed only if one knows the exact location of the memory. In the brain,
information can be accessed through spreading activation from closely related concepts.
The brain operates primarily in parallel, meaning that it is multitasking on many different actions at the same
time. Although this is changing as new computers are developed, most computers are primarily serial—they
finish one task before they start another.
In computers, short-term (random-access) memory is a subset of long-term (read-only) memory. In the brain,
the processes of short-term memory and long-term memory are distinct.
In the brain, there is no difference between hardware (the mechanical aspects of the computer) and software (the
programs that run on the hardware).
In the brain, synapses, which operate using an electrochemical process, are much slower but also vastly more
complex and useful than the transistors used by computers.
Computers differentiate memory (e.g., the hard drive) from processing (the central processing unit), but in brains
there is no such distinction. In the brain (but not in computers) existing memory is used to interpret and store
incoming information, and retrieving information from memory changes the memory itself.
The brain is self-organizing and self-repairing, but computers are not. If a person suffers a stroke, neural
plasticity will help him or her recover. If we drop our laptop and it breaks, it cannot fix itself.
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The brain is significantly bigger than any current computer. The brain is estimated to have
25,000,000,000,000,000 (25 million billion) interactions among axons, dendrites, neurons, and
neurotransmitters, and that doesn’t include the approximately 1 trillion glial cells that may also be important for
information processing and memory.
Although cognitive psychology began in earnest at about the same time that the electronic computer was first being
developed, and although cognitive psychologists have frequently used the computer as a model for understanding
how the brain operates, research in cognitive neuroscience has revealed many important differences between brains
and computers. The neuroscientist Chris Chatham (2007) [3]
provided the list of differences between brains and
computers shown here. You might want to check out the website and the responses to it
athttp://scienceblogs.com/developingintelligence/2007/03/why_the_brain_is_not_ like_a_co.php.
We will begin the chapter with the study of memory. Our memories allow us to do relatively
simple things, such as remembering where we parked our car or the name of the current
president of the United States, but also allow us to form complex memories, such as how to ride
a bicycle or to write a computer program. Moreover, our memories define us as individuals—
they are our experiences, our relationships, our successes, and our failures. Without our
memories, we would not have a life.
At least for some things, our memory is very good (Bahrick, 2000). [4]
Once we learn a face, we
can recognize that face many years later. We know the lyrics of many songs by heart, and we can
give definitions for tens of thousands of words. Mitchell (2006) [5]
contacted participants 17
years after they had been briefly exposed to some line drawings in a lab and found that they still
could identify the images significantly better than participants who had never seen them.
For some people, memory is truly amazing. Consider, for instance, the case of Kim Peek, who
was the inspiration for the Academy Award–winning film Rain Man (Figure 8.1 "Kim
Peek" andNote 8.5 "Video Clip: Kim Peek"). Although Peek’s IQ was only 87, significantly
below the average of about 100, it is estimated that he memorized more than 10,000 books in his
lifetime (Wisconsin Medical Society, n.d.; ―Kim Peek,‖ 2004). [6]
The Russian psychologist A.
R. Luria (2004) [7]
has described the abilities of a man known as ―S,‖ who seems to have
unlimited memory. S remembers strings of hundreds of random letters for years at a time, and
seems in fact to never forget anything.
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Video Clip: Kim Peek
You can view an interview with Kim Peek and see some of his amazing memory abilities at this
link.
In this chapter we will see how psychologists use behavioral responses (such as memory tests
and reaction times) to draw inferences about what and how people remember. And we will see
that although we have very good memory for some things, our memories are far from perfect
(Schacter, 1996). [8]
The errors that we make are due to the fact that our memories are not simply
recording devices that input, store, and retrieve the world around us. Rather, we actively process
and interpret information as we remember and recollect it, and these cognitive processes
influence what we remember and how we remember it. Because memories are constructed, not
recorded, when we remember events we don’t reproduce exact replicas of those events (Bartlett,
1932). [9]
In the last section of the chapter we will focus primarily on cognition, with a particular
consideration for cases in which cognitive processes lead us to distort our judgments or
misremember information. We will see that our prior knowledge can influence our memory.
People who read the words ―dream,sheets, rest, snore, blanket, tired, and bed‖ and then are
asked to remember the words often think that they saw the word sleep even though that word
was not in the list (Roediger & McDermott, 1995). [10]
And we will see that in other cases we are
influenced by the ease with which we can retrieve information from memory or by the
information that we are exposed to after we first learn something.
Although much research in the area of memory and cognition is basic in orientation, the work
also has profound influence on our everyday experiences. Our cognitive processes influence the
accuracy and inaccuracy of our memories and our judgments, and they lead us to be vulnerable
to the types of errors that eyewitnesses such as Jennifer Thompson may make. Understanding
these potential errors is the first step in learning to avoid them.
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[1] Innocence Project. (n.d.). Ronald Cotton. Retrieved fromhttp://www.innocenceproject.org/Content/72.php; Thompson, J.
(2000, June 18). I was certain, but I was wrong. New York Times. Retrieved
fromhttp://faculty.washington.edu/gloftus/Other_Information/Legal_Stuff/Articles/News_Articles/Thompson_NYT_6_18_2000.
html
[2] Wells, G. L., Memon, A., & Penrod, S. D. (2006). Eyewitness evidence: Improving its probative value. Psychological Science in
the Public Interest, 7(2), 45–75.
[3] Chatham, C. (2007, March 27). 10 important differences between brains and computers. Developing Intelligence. Retrieved
fromhttp://scienceblogs.com/developingintelligence/2007/03/why_the_brain_ is_not_like_a_co.php
[4] Bahrick, H. P. (2000). Long-term maintenance of knowledge. In E. Tulving & F. I. M. Craik (Eds.), The Oxford handbook of
memory (pp. 347–362). New York, NY: Oxford University Press.
[5] Mitchell, D. B. (2006). Nonconscious priming after 17 years: Invulnerable implicit memory? Psychological Science, 17(11),
925–928.
[6] Wisconsin Medical Society. (n.d.). Retrieved
fromhttp://www.wisconsinmedicalsociety.org/_SAVANT/_PROFILES/kim_peek/_media/video/expedition/video.html; Kim
Peek: Savant who was the inspiration for the film Rain Man. (2009, December 23). The Times. Retrieved
fromhttp://www.timesonline.co.uk/tol/comment/obituaries/article6965115.ece
[7] Luria, A. (2004). The mind of a mnemonist: A little book about a vast memory.Cambridge, MA: Harvard University Press.
[8] Schacter, D. L. (1996). Searching for memory: The brain, the mind, and the past (1st ed.). New York, NY: Basic Books.
[9] Bartlett, F. C. (1932). Remembering. Cambridge, MA: Cambridge University Press.
[10] Roediger, H. L., & McDermott, K. B. (1995). Creating false memories: Remembering words not presented in lists. Journal of
Experimental Psychology: Learning, Memory, and Cognition, 21(4), 803–814.
8.1 Memories as Types and Stages L E A R N I N G O B J E C T I V E S
1. Compare and contrast explicit and implicit memory, identifying the features that define each.
2. Explain the function and duration of eidetic and echoic memories.
3. Summarize the capacities of short-term memory and explain how working memory is used to process information in
it.
As you can see in Table 8.1 "Memory Conceptualized in Terms of Types, Stages, and
Processes", psychologists conceptualize memory in terms of types, in terms of stages, and in
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terms of processes. In this section we will consider the two types of memory, explicit
memory and implicit memory, and then the three major memory stages: sensory, short-term,
and long-term (Atkinson & Shiffrin, 1968). [1]
Then, in the next section, we will consider the
nature of long-term memory, with a particular emphasis on the cognitive techniques we can use
to improve our memories. Our discussion will focus on the three processes that are central to
long-term memory: encoding, storage, and retrieval.
Table 8.1 Memory Conceptualized in Terms of Types, Stages, and Processes
As types
Explicit memory
Implicit memory
As stages
Sensory memory
Short-term memory
Long-term memory
As processes
Encoding
Storage
Retrieval
Explicit Memory
When we assess memory by asking a person to consciously remember things, we are
measuring explicit memory. Explicit memory refers to knowledge or experiences that can be
consciously remembered. As you can see in Figure 8.2 "Types of Memory", there are two types
of explicit memory: episodic andsemantic. Episodic memory refers to the firsthand experiences
that we have had (e.g., recollections of our high school graduation day or of the fantastic dinner
we had in New York last year). Semantic memory refers to our knowledge of facts and concepts
about the world (e.g., that the absolute value of −90 is greater than the absolute value of 9 and
that one definition of the word ―affect‖ is ―the experience of feeling or emotion‖).
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Figure 8.2 Types of Memory
Explicit memory is assessed using measures in which the individual being tested must
consciously attempt to remember the information. Arecall memory test is a measure of explicit
memory that involves bringing from memory information that has previously been remembered.
We rely on our recall memory when we take an essay test, because the test requires us to
generate previously remembered information. A multiple-choice test is an example of
a recognition memory test, a measure of explicit memory that involves determining whether
information has been seen or learned before.
Your own experiences taking tests will probably lead you to agree with the scientific research
finding that recall is more difficult than recognition. Recall, such as required on essay tests,
involves two steps: first generating an answer and then determining whether it seems to be the
correct one. Recognition, as on multiple-choice test, only involves determining which item from
a list seems most correct (Haist, Shimamura, & Squire, 1992). [2]
Although they involve different
processes, recall and recognition memory measures tend to be correlated. Students who do better
on a multiple-choice exam will also, by and large, do better on an essay exam (Bridgeman &
Morgan, 1996). [3]
A third way of measuring memory is known as relearning (Nelson, 1985). [4]
Measures
of relearning (or savings) assess how much more quickly information is processed or learned
when it is studied again after it has already been learned but then forgotten. If you have taken
some French courses in the past, for instance, you might have forgotten most of the vocabulary
you learned. But if you were to work on your French again, you’d learn the vocabulary much
faster the second time around. Relearning can be a more sensitive measure of memory than either
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recall or recognition because it allows assessing memory in terms of ―how much‖ or ―how fast‖
rather than simply ―correct‖ versus ―incorrect‖ responses. Relearning also allows us to measure
memory for procedures like driving a car or playing a piano piece, as well as memory for facts
and figures.
Implicit Memory
While explicit memory consists of the things that we can consciously report that we know,
implicit memory refers to knowledge that we cannot consciously access. However, implicit
memory is nevertheless exceedingly important to us because it has a direct effect on our
behavior. Implicit memory refers to the influence of experience on behavior, even if the
individual is not aware of those influences. As you can see in Figure 8.2 "Types of Memory",
there are three general types of implicit memory: procedural memory, classical conditioning
effects, and priming.
Procedural memory refers to our often unexplainable knowledge of how to do things. When we
walk from one place to another, speak to another person in English, dial a cell phone, or play a
video game, we are using procedural memory. Procedural memory allows us to perform complex
tasks, even though we may not be able to explain to others how we do them. There is no way to
tell someone how to ride a bicycle; a person has to learn by doing it. The idea of implicit
memory helps explain how infants are able to learn. The ability to crawl, walk, and talk are
procedures, and these skills are easily and efficiently developed while we are children despite the
fact that as adults we have no conscious memory of having learned them.
A second type of implicit memory is classical conditioning effects, in which we learn, often
without effort or awareness, to associate neutral stimuli (such as a sound or a light) with another
stimulus (such as food), which creates a naturally occurring response, such as enjoyment or
salivation. The memory for the association is demonstrated when the conditioned stimulus (the
sound) begins to create the same response as the unconditioned stimulus (the food) did before the
learning.
The final type of implicit memory is known as priming, or changes in behavior as a result of
experiences that have happened frequently or recently. Priming refers both to the activation of
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knowledge (e.g., we can prime the concept of ―kindness‖ by presenting people with words
related to kindness) and to the influence of that activation on behavior (people who are primed
with the concept of kindness may act more kindly).
One measure of the influence of priming on implicit memory is the word fragment test, in which
a person is asked to fill in missing letters to make words. You can try this yourself: First, try to
complete the following word fragments, but work on each one for only three or four seconds. Do
any words pop into mind quickly?
_ i b _ a _ y
_ h _ s _ _ i _ n
_ o _ k
_ h _ i s _
Now read the following sentence carefully:
“He got his materials from the shelves, checked them out, and then left the building.”
Then try again to make words out of the word fragments.
I think you might find that it is easier to complete fragments 1 and 3 as ―library‖ and ―book,‖
respectively, after you read the sentence than it was before you read it. However, reading the
sentence didn’t really help you to complete fragments 2 and 4 as ―physician‖ and ―chaise.‖ This
difference in implicit memory probably occurred because as you read the sentence, the concept
of ―library‖ (and perhaps ―book‖) was primed, even though they were never mentioned
explicitly. Once a concept is primed it influences our behaviors, for instance, on word fragment
tests.
Our everyday behaviors are influenced by priming in a wide variety of situations. Seeing an
advertisement for cigarettes may make us start smoking, seeing the flag of our home country
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may arouse our patriotism, and seeing a student from a rival school may arouse our competitive
spirit. And these influences on our behaviors may occur without our being aware of them.
Research Focus: Priming Outside Awareness Influences Behavior
One of the most important characteristics of implicit memories is that they are frequently formed and
used automatically, without much effort or awareness on our part. In one demonstration of the automaticity and
influence of priming effects, John Bargh and his colleagues (Bargh, Chen, & Burrows, 1996) [5]
conducted a study in
which they showed college students lists of five scrambled words, each of which they were to make into a sentence.
Furthermore, for half of the research participants, the words were related to stereotypes of the elderly. These
participants saw words such as the following:
in Florida retired live people
bingo man the forgetful plays
The other half of the research participants also made sentences, but from words that had nothing to do with elderly
stereotypes. The purpose of this task was to prime stereotypes of elderly people in memory for some of the
participants but not for others.
The experimenters then assessed whether the priming of elderly stereotypes would have any effect on the students’
behavior—and indeed it did. When the research participant had gathered all of his or her belongings, thinking that the
experiment was over, the experimenter thanked him or her for participating and gave directions to the closest
elevator. Then, without the participants knowing it, the experimenters recorded the amount of time that the
participant spent walking from the doorway of the experimental room toward the elevator. As you can see in Figure
8.3 "Results From Bargh, Chen, and Burrows, 1996", participants who had made sentences using words related to
elderly stereotypes took on the behaviors of the elderly—they walked significantly more slowly as they left the
experimental room.
Figure 8.3Results From Bargh, Chen, and Burrows, 1996
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Bargh, Chen, and Burrows (1996) found that priming words associated with the elderly made people walk more
slowly.
Source: Adapted from Bargh, J. A., Chen, M., & Burrows, L. (1996). Automaticity of social behavior: Direct effects
of trait construct and stereotype activation on action. Journal of Personality & Social Psychology, 71, 230–244.
To determine if these priming effects occurred out of the awareness of the participants, Bargh and his colleagues
asked still another group of students to complete the priming task and then to indicate whether they thought the
words they had used to make the sentences had any relationship to each other, or could possibly have influenced their
behavior in any way. These students had no awareness of the possibility that the words might have been related to the
elderly or could have influenced their behavior.
Stages of Memory: Sensory, Short-Term, and Long-Term Memory
Another way of understanding memory is to think about it in terms of stages that describe the
length of time that information remains available to us. According to this approach (see Figure
8.4 "Memory Duration"), information begins in sensory memory, moves to short-term memory,
and eventually moves to long-term memory. But not all information makes it through all three
stages; most of it is forgotten. Whether the information moves from shorter-duration memory
into longer-duration memory or whether it is lost from memory entirely depends on how the
information is attended to and processed.
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Figure 8.4 Memory Duration
Memory can characterized in terms of stages—the length of time that information remains available to us.
Source: Adapted from Atkinson, R. C., & Shiffrin, R. M. (1968). Human memory: A proposed system and its control
processes. In K. Spence (Ed.), The psychology of learning and motivation (Vol. 2). Oxford, England: Academic
Press.
Sensory Memory
Sensory memory refers to the brief storage of sensory information. Sensory memory is a
memory buffer that lasts only very briefly and then, unless it is attended to and passed on for
more processing, is forgotten. The purpose of sensory memory is to give the brain some time to
process the incoming sensations, and to allow us to see the world as an unbroken stream of
events rather than as individual pieces.
Visual sensory memory is known as iconic memory. Iconic memory was first studied by the
psychologist George Sperling (1960). [6]
In his research, Sperling showed participants a display
of letters in rows, similar to that shown in Figure 8.5 "Measuring Iconic Memory". However, the
display lasted only about 50 milliseconds (1/20 of a second). Then, Sperling gave his participants
a recall test in which they were asked to name all the letters that they could remember. On
average, the participants could remember only about one-quarter of the letters that they had seen.
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Figure 8.5 Measuring Iconic Memory
Sperling (1960) showed his participants displays such as this one for only 1/20th of a second. He found that when
he cued the participants to report one of the three rows of letters, they could do it, even if the cue was given shortly
after the display had been removed. The research demonstrated the existence of iconic memory.
Source: Adapted from Sperling, G. (1960). The information available in brief visual presentation. Psychological
Monographs, 74(11), 1–29.
Sperling reasoned that the participants had seen all the letters but could remember them only
very briefly, making it impossible for them to report them all. To test this idea, in his next
experiment he first showed the same letters, but then after the display had been removed, he
signaled to the participants to report the letters from either the first, second, or third row. In this
condition, the participants now reported almost all the letters in that row. This finding confirmed
Sperling’s hunch: Participants had access to all of the letters in their iconic memories, and if the
task was short enough, they were able to report on the part of the display he asked them to. The
―short enough‖ is the length of iconic memory, which turns out to be about 250 milliseconds (¼
of a second).
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Auditory sensory memory is known as echoic memory. In contrast to iconic memories, which
decay very rapidly, echoic memories can last as long as 4 seconds (Cowan, Lichty, & Grove,
1990). [7]
This is convenient as it allows you—among other things—to remember the words that
you said at the beginning of a long sentence when you get to the end of it, and to take notes on
your psychology professor’s most recent statement even after he or she has finished saying it.
In some people iconic memory seems to last longer, a phenomenon known as eidetic imagery (or
―photographic memory‖) in which people can report details of an image over long periods of
time. These people, who often suffer from psychological disorders such as autism, claim that
they can ―see‖ an image long after it has been presented, and can often report accurately on that
image. There is also some evidence for eidetic memories in hearing; some people report that
their echoic memories persist for unusually long periods of time. The composer Wolfgang
Amadeus Mozart may have possessed eidetic memory for music, because even when he was
very young and had not yet had a great deal of musical training, he could listen to long
compositions and then play them back almost perfectly (Solomon, 1995). [8]
Short-Term Memory
Most of the information that gets into sensory memory is forgotten, but information that we turn
our attention to, with the goal of remembering it, may pass into short-term memory. Short-
term memory (STM) is the place where small amounts of information can be temporarily kept
for more than a few seconds but usually for less than one minute (Baddeley, Vallar, & Shallice,
1990). [9]
Information in short-term memory is not stored permanently but rather becomes
available for us to process, and the processes that we use to make sense of, modify, interpret, and
store information in STM are known as working memory.
Although it is called ―memory,‖ working memory is not a store of memory like STM but rather a
set of memory procedures or operations. Imagine, for instance, that you are asked to participate
in a task such as this one, which is a measure of working memory (Unsworth & Engle,
2007). [10]
Each of the following questions appears individually on a computer screen and then
disappears after you answer the question:
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Is 10 × 2 − 5 = 15? (Answer YES OR NO) Then remember ―S‖
Is 12 ÷ 6 − 2 = 1? (Answer YES OR NO) Then remember ―R‖
Is 10 × 2 = 5? (Answer YES OR NO) Then remember ―P‖
Is 8 ÷ 2 − 1 = 1? (Answer YES OR NO) Then remember ―T‖
Is 6 × 2 − 1 = 8? (Answer YES OR NO) Then remember ―U‖
Is 2 × 3 − 3 = 0? (Answer YES OR NO) Then remember ―Q‖
To successfully accomplish the task, you have to answer each of the math problems correctly and
at the same time remember the letter that follows the task. Then, after the six questions, you must
list the letters that appeared in each of the trials in the correct order (in this case S, R, P, T, U, Q).
To accomplish this difficult task you need to use a variety of skills. You clearly need to use
STM, as you must keep the letters in storage until you are asked to list them. But you also need a
way to make the best use of your available attention and processing. For instance, you might
decide to use a strategy of ―repeat the letters twice, then quickly solve the next problem, and then
repeat the letters twice again including the new one.‖ Keeping this strategy (or others like it)
going is the role of working memory’s central executive—the part of working memory that
directs attention and processing. The central executive will make use of whatever strategies seem
to be best for the given task. For instance, the central executive will direct the rehearsal process,
and at the same time direct the visual cortex to form an image of the list of letters in memory.
You can see that although STM is involved, the processes that we use to operate on the material
in memory are also critical.
Short-term memory is limited in both the length and the amount of information it can hold.
Peterson and Peterson (1959) [11]
found that when people were asked to remember a list of three-
letter strings and then were immediately asked to perform a distracting task (counting backward
by threes), the material was quickly forgotten (see Figure 8.6 "STM Decay"), such that by 18
seconds it was virtually gone.
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Figure 8.6 STM Decay
Peterson and Peterson (1959) found that information that was not rehearsed decayed quickly from memory.
Source: Adapted from Peterson, L., & Peterson, M. J. (1959). Short-term retention of individual verbal
items. Journal of Experimental Psychology, 58(3), 193–198.
One way to prevent the decay of information from short-term memory is to use working memory
to rehearse it. Maintenance rehearsal is the process of repeating information mentally or out loud
with the goal of keeping it in memory. We engage in maintenance rehearsal to keep a something
that we want to remember (e.g., a person’s name, e-mail address, or phone number) in mind long
enough to write it down, use it, or potentially transfer it to long-term memory.
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If we continue to rehearse information it will stay in STM until we stop rehearsing it, but there is
also a capacity limit to STM. Try reading each of the following rows of numbers, one row at a
time, at a rate of about one number each second. Then when you have finished each row, close
your eyes and write down as many of the numbers as you can remember.
019
3586
10295
861059
1029384
75674834
657874104
6550423897
If you are like the average person, you will have found that on this test of working memory,
known as a digit span test, you did pretty well up to about the fourth line, and then you started
having trouble. I bet you missed some of the numbers in the last three rows, and did pretty poorly
on the last one.
The digit span of most adults is between five and nine digits, with an average of about seven.
The cognitive psychologist George Miller (1956) [12]
referred to ―seven plus or minus two‖
pieces of information as the ―magic number‖ in short-term memory. But if we can only hold a
maximum of about nine digits in short-term memory, then how can we remember larger amounts
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of information than this? For instance, how can we ever remember a 10-digit phone number long
enough to dial it?
One way we are able to expand our ability to remember things in STM is by using a memory
technique called chunking. Chunking is the process of organizing information into smaller
groupings (chunks), thereby increasing the number of items that can be held in STM. For
instance, try to remember this string of 12 letters:
XOFCBANNCVTM
You probably won’t do that well because the number of letters is more than the magic number of
seven.
Now try again with this one:
MTVCNNABCFOX
Would it help you if I pointed out that the material in this string could be chunked into four sets
of three letters each? I think it would, because then rather than remembering 12 letters, you
would only have to remember the names of four television stations. In this case, chunking
changes the number of items you have to remember from 12 to only four.
Experts rely on chunking to help them process complex information. Herbert Simon and William
Chase (1973) [13]
showed chess masters and chess novices various positions of pieces on a
chessboard for a few seconds each. The experts did a lot better than the novices in remembering
the positions because they were able to see the ―big picture.‖ They didn’t have to remember the
position of each of the pieces individually, but chunked the pieces into several larger layouts. But
when the researchers showed both groups random chess positions—positions that would be very
unlikely to occur in real games—both groups did equally poorly, because in this situation the
experts lost their ability to organize the layouts (see Figure 8.7 "Possible and Impossible Chess
Positions"). The same occurs for basketball. Basketball players recall actual basketball positions
much better than do nonplayers, but only when the positions make sense in terms of what is
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happening on the court, or what is likely to happen in the near future, and thus can be chunked
into bigger units (Didierjean & Marmèche, 2005). [14]
Figure 8.7 Possible and Impossible Chess Positions
Experience matters: Experienced chess players are able to recall the positions of the game on the right much better
than are those who are chess novices. But the experts do no better than the novices in remembering the positions on
the left, which cannot occur in a real game.
If information makes it past short term-memory it may enter long-term memory (LTM), memory
storage that can hold information for days, months, and years. The capacity of long-term
memory is large, and there is no known limit to what we can remember (Wang, Liu, & Wang,
2003). [15]
Although we may forget at least some information after we learn it, other things will
stay with us forever. In the next section we will discuss the principles of long-term memory. K E Y T A K E A W A Y S
Memory refers to the ability to store and retrieve information over time.
For some things our memory is very good, but our active cognitive processing of information assures that memory is
never an exact replica of what we have experienced.
Explicit memory refers to experiences that can be intentionally and consciously remembered, and it is measured using
recall, recognition, and relearning. Explicit memory includes episodic and semantic memories.
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Measures of relearning (also known as savings) assess how much more quickly information is learned when it is
studied again after it has already been learned but then forgotten.
Implicit memory refers to the influence of experience on behavior, even if the individual is not aware of those
influences. The three types of implicit memory are procedural memory, classical conditioning, and priming.
Information processing begins in sensory memory, moves to short-term memory, and eventually moves to long-term
memory.
Maintenance rehearsal and chunking are used to keep information in short-term memory.
The capacity of long-term memory is large, and there is no known limit to what we can remember.
E X E R C I S E S A N D C R I T I C A L T H I N K I N G
1. List some situations in which sensory memory is useful for you. What do you think your experience of the stimuli
would be like if you had no sensory memory?
2. Describe a situation in which you need to use working memory to perform a task or solve a problem. How do your
working memory skills help you?
[1] Atkinson, R. C., & Shiffrin, R. M. (1968). Human memory: A proposed system and its control processes. In K. Spence
(Ed.), The psychology of learning and motivation (Vol. 2). Oxford, England: Academic Press.
[2] Haist, F., Shimamura, A. P., & Squire, L. R. (1992). On the relationship between recall and recognition memory. Journal of
Experimental Psychology: Learning, Memory, and Cognition, 18(4), 691–702.
[3] Bridgeman, B., & Morgan, R. (1996). Success in college for students with discrepancies between performance on multiple-
choice and essay tests. Journal of Educational Psychology, 88(2), 333–340.
[4] Nelson, T. O. (1985). Ebbinghaus’s contribution to the measurement of retention: Savings during relearning. Journal of
Experimental Psychology: Learning, Memory, and Cognition, 11(3), 472–478.
[5] Bargh, J. A., Chen, M., & Burrows, L. (1996). Automaticity of social behavior: Direct effects of trait construct and stereotype
activation on action. Journal of Personality & Social Psychology, 71, 230–244.
[6] Sperling, G. (1960). The information available in brief visual presentation.Psychological Monographs, 74(11), 1–29.
[7] Cowan, N., Lichty, W., & Grove, T. R. (1990). Properties of memory for unattended spoken syllables. Journal of Experimental
Psychology: Learning, Memory, and Cognition, 16(2), 258–268.
[8] Solomon, M. (1995). Mozart: A life. New York, NY: Harper Perennial.
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[9] Baddeley, A. D., Vallar, G., & Shallice, T. (1990). The development of the concept of working memory: Implications and
contributions of neuropsychology. In G. Vallar & T. Shallice (Eds.), Neuropsychological impairments of short-term memory (pp.
54–73). New York, NY: Cambridge University Press.
[10] Unsworth, N., & Engle, R. W. (2007). On the division of short-term and working memory: An examination of simple and
complex span and their relation to higher order abilities. Psychological Bulletin, 133(6), 1038–1066.
[11] Peterson, L., & Peterson, M. J. (1959). Short-term retention of individual verbal items.Journal of Experimental Psychology,
58(3), 193–198.
[12] Miller, G. A. (1956). The magical number seven, plus or minus two: Some limits on our capacity for processing
information. Psychological Review, 63(2), 81–97.
[13] Simon, H. A., & Chase, W. G. (1973). Skill in chess. American Scientist, 61(4), 394–403.
[14] Didierjean, A., & Marmèche, E. (2005). Anticipatory representation of visual basketball scenes by novice and expert
players. Visual Cognition, 12(2), 265–283.
[15] Wang, Y., Liu, D., & Wang, Y. (2003). Discovering the capacity of human memory. Brain & Mind, 4(2), 189–198.
8.2 How We Remember: Cues to Improving Memory L E A R N I N G O B J E C T I V E S
1. Label and review the principles of encoding, storage, and retrieval.
2. Summarize the types of amnesia and their effects on memory.
3. Describe how the context in which we learn information can influence our memory of that information.
Although it is useful to hold information in sensory and short-term memory, we also rely on our
long-term memory (LTM). We want to remember the name of the new boy in the class, the name
of the movie we saw last week, and the material for our upcoming psychology test.
Psychological research has produced a great deal of knowledge about long-term memory, and
this research can be useful as you try to learn and remember new material (see Table 8.2
"Helpful Memory Techniques Based on Psychological Research"). In this section we will
consider this question in terms of the types of processing that we do on the information we want
to remember. To be successful, the information that we want to remember must
be encoded and stored, and then retrieved.
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Table 8.2 Helpful Memory Techniques Based on Psychological Research
Technique Description Useful example
Use elaborative
encoding.
Material is better remembered if it is
processed more fully.
Think, for instance, ―Proactive interference is like
retroactive interference but it occurs in a forward manner.‖
Make use of the
self-reference
effect.
Material is better remembered if it is
linked to thoughts about the self.
Think, for instance, ―I remember a time when I knew the
answer to an exam question but couldn’t quite get it to come
to mind. This was an example of the tip-of-the-tongue
phenomenon.‖
Be aware of the
forgetting curve.
Information that we have learned drops
off rapidly with time.
Review the material that you have already studied right
before the exam to increase the likelihood it will remain in
memory.
Make use of the
spacing effect.
Information is learned better when it is
studied in shorter periods spaced over
time. Study a little bit every day; do not cram at the last minute.
Rely on
overlearning.
We can continue to learn even after we
think we know the information
perfectly. Keep studying, even if you think you already have it down.
Use context-
dependent
retrieval.
We have better retrieval when it occurs
in the same situation in which we
learned the material.
If possible, study under conditions similar to the conditions
in which you will take the exam.
Use state-
dependent
retrieval.
We have better retrieval when we are
in the same psychological state as we
were when we learned the material.
Many possibilities, but don’t study under the influence of
drugs or alcohol, unless you plan to use them on the day of
the exam (which is not recommended).
Encoding and Storage: How Our Perceptions Become Memories
Encoding is the process by which we place the things that we experience into memory. Unless
information is encoded, it cannot be remembered. I’m sure you’ve been to a party where you’ve
been introduced to someone and then—maybe only seconds later—you realize that you do not
remember the person’s name. Of course it’s not really surprising that you can’t remember the
name, because you probably were distracted and you never encoded the name to begin with.
Not everything we experience can or should be encoded. We tend to encode things that we need
to remember and not bother to encode things that are irrelevant. Look at Figure 8.8 "Pennies in
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Different Styles", which shows different images of U.S. pennies. Can you tell which one is the
real one? Nickerson and Adams (1979) [1]
found that very few of the U.S. participants they tested
could identify the right one. We see pennies a lot, but we don’t bother to encode their features.
Figure 8.8 Pennies in Different Styles
Can you identify the ―real‖ penny? We tend to have poor memory for things that don’t matter, even if we see them
frequently.
One way to improve our memory is to use better encoding strategies. Some ways of studying are
more effective than others. Research has found that we are better able to remember information
if we encode it in a meaningful way. When we engage in elaborative encoding we process new
information in ways that make it more relevant or meaningful (Craik & Lockhart, 1972; Harris &
Qualls, 2000). [2]
Imagine that you are trying to remember the characteristics of the different schools of
psychology we discussed in Chapter 1 "Introducing Psychology". Rather than simply trying to
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remember the schools and their characteristics, you might try to relate the information to things
you already know. For instance, you might try to remember the fundamentals of the cognitive
school of psychology by linking the characteristics to the computer model. The cognitive school
focuses on how information is input, processed, and retrieved, and you might think about how
computers do pretty much the same thing. You might also try to organize the information into
meaningful units. For instance, you might link the cognitive school to structuralism because both
were concerned with mental processes. You also might try to use visual cues to help you
remember the information. You might look at the image of Freud and imagine what he looked
like as a child. That image might help you remember that childhood experiences were an
important part of Freudian theory. Each person has his or her unique way of elaborating on
information; the important thing is to try to develop unique and meaningful associations among
the materials.
Research Focus: Elaboration and Memory
In an important study showing the effectiveness of elaborative encoding, Rogers, Kuiper, and Kirker (1977) [3]
studied
how people recalled information that they had learned under different processing conditions. All the participants
were presented with the same list of 40 adjectives to learn, but through the use of random assignment, the
participants were given one of four different sets of instructions about how to process the adjectives.
Participants assigned to the structural task condition were asked to judge whether the word was printed in uppercase
or lowercase letters. Participants in the phonemic task condition were asked whether or not the word rhymed with
another given word. In the semantic task condition, the participants were asked if the word was a synonym of another
word. And in the self-reference task condition, participants were asked to indicate whether or not the given adjective
was or was not true of themselves. After completing the specified task, each participant was asked to recall as many
adjectives as he or she could remember.
Rogers and his colleagues hypothesized that different types of processing would have different effects on memory. As
you can see in Figure 8.9 "Self-Reference Effect Results", the students in the self-reference task condition recalled
significantly more adjectives than did students in any other condition. This finding, known as the self-reference effect,
is powerful evidence that the self-concept helps us organize and remember information. The next time you are
studying for an exam, you might try relating the material to your own experiences. The self-reference effect suggests
that doing so will help you better remember the information (Symons & Johnson, 1997). [4]
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Figure 8.9Self-Reference Effect Results
Participants recalled the same words significantly better when they were processed in relation to the self than when
they were processed in other ways.
Source: Adapted from Rogers, T. B., Kuiper, N. A., & Kirker, W. S. (1977). Self-reference and the encoding of
personal information. Journal of Personality & Social Psychology, 35(9), 677–688.
Using the Contributions of Hermann Ebbinghaus to Improve Your Memory
Hermann Ebbinghaus (1850–1909) was a pioneer of the study of memory. In this section we
consider three of his most important findings, each of which can help you improve your memory.
In his research, in which he was the only research participant, Ebbinghaus practiced memorizing
lists of nonsense syllables, such as the following:
DIF, LAJ, LEQ, MUV, WYC, DAL, SEN, KEP, NUD
You can imagine that because the material that he was trying to learn was not at all meaningful,
it was not easy to do. Ebbinghaus plotted how many of the syllables he could remember against
the time that had elapsed since he had studied them. He discovered an important principle of
memory: Memory decays rapidly at first, but the amount of decay levels off with time (Figure
8.10 "Ebbinghaus Forgetting Curve"). Although Ebbinghaus looked at forgetting after days had
elapsed, the same effect occurs on longer and shorter time scales. Bahrick (1984) [5]
found that
students who took a Spanish language course forgot about one half of the vocabulary that they
had learned within three years, but that after that time their memory remained pretty much
constant. Forgetting also drops off quickly on a shorter time frame. This suggests that you should
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try to review the material that you have already studied right before you take an exam; that way,
you will be more likely to remember the material during the exam.
Figure 8.10 Ebbinghaus Forgetting Curve
Hermann Ebbinghaus found that memory for information drops off rapidly at first but then levels off after time.
Ebbinghaus also discovered another important principle of learning, known as the spacing effect.
The spacing effect refers to the fact that learning is better when the same amount of study is
spread out over periods of time than it is when it occurs closer together or at the same time. This
means that even if you have only a limited amount of time to study, you’ll learn more if you
study continually throughout the semester (a little bit every day is best) than if you wait to cram
at the last minute before your exam (Figure 8.11 "Effects of Massed Versus Distributed Practice
on Learning"). Another good strategy is to study and then wait as long as you can before you
forget the material. Then review the information and again wait as long as you can before you
forget it. (This probably will be a longer period of time than the first time.) Repeat and repeat
again. The spacing effect is usually considered in terms of the difference between distributed
practice (practice that is spread out over time) and massed practice (practice that comes in one
block), with the former approach producing better memory.
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Figure 8.11 Effects of Massed Versus Distributed Practice on Learning
The spacing effect refers to the fact that memory is better when it is distributedrather than massed. Leslie, Lee Ann,
and Nora all studied for four hours total, but the students who spread out their learning into smaller study sessions
did better on the exam.
Ebbinghaus also considered the role of overlearning—that is, continuing to practice and study
even when we think that we have mastered the material. Ebbinghaus and other researchers have
found that overlearning helps encoding (Driskell, Willis, & Copper, 1992). [6]
Students
frequently think that they have already mastered the material but then discover when they get to
the exam that they have not. The point is clear: Try to keep studying and reviewing, even if you
think you already know all the material.
Retrieval
Even when information has been adequately encoded and stored, it does not do us any good if we
cannot retrieve it. Retrieval refers to the process of reactivating information that has been stored
in memory. You can get an idea of the difficulty posed by retrieval by simply reading each of the
words (but not the categories) in the sidebar below to someone. Tell the person that after you
have read all the words, you will ask her to recall the words.
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After you read the list to your friend, give her enough time to write down all the words that she
can recall. Make sure that she cannot recall any more and then, for the words that were not listed,
prompt your friend with some of the category names: ―Do you remember any words that were
furniture? Do you remember any words that were tools?‖ I think you will find that the category
names, which serve as retrieval cues, will help your friend remember information that she could
not retrieve otherwise.
Retrieval Demonstration
Try this test of the ability to retrieve information with a classmate. The instructions are in the text.
Apple (Fruit)
Dresser (Furniture)
Sander (Tool)
Pomegranate (Fruit)
Sunflower (Flower)
Tangerine (Fruit)
Chair (Furniture)
Peony (Flower)
Banana (Fruit)
Sofa (Furniture)
Bench (Furniture)
Strawberry (Fruit)
Television stand (Furniture)
Magnolia (Flower)
Rose (Flower)
Wrench (Tool)
Screwdriver (Tool)
Dahlia (Flower)
Drill press (Tool)
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Hammer (Tool)
We’ve all experienced retrieval failure in the form of the frustrating tip-of-the-
tongue phenomenon, in which we are certain that we know something that we are trying to
recall but cannot quite come up with it. You can try this one on your friends as well. Read your
friend the names of the 10 states listed in the sidebar below, and ask him to name the capital city
of each state. Now, for the capital cities that your friend can’t name, give him just the first letter
of the capital city. You’ll probably find that having the first letters of the cities helps with
retrieval. The tip-of-the-tongue experience is a very good example of the inability to retrieve
information that is actually stored in memory.
States and Capital Cities
Try this demonstration of the tip-of-the-tongue phenomenon with a classmate. Instructions are in the text.
Georgia (Atlanta)
Maryland (Annapolis)
California (Sacramento)
Louisiana (Baton Rouge)
Florida (Tallahassee)
Colorado (Denver)
New Jersey (Trenton)
Arizona (Phoenix)
Nebraska (Lincoln)
Kentucky (Frankfort)
We are more likely to be able to retrieve items from memory when conditions at retrieval are
similar to the conditions under which we encoded them. Context-dependent learning refers to an
increase in retrieval when the external situation in which information is learned matches the
situation in which it is remembered. Godden and Baddeley (1975) [7]
conducted a study to test
this idea using scuba divers. They asked the divers to learn a list of words either when they were
on land or when they were underwater. Then they tested the divers on their memory, either in the
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same or the opposite situation. As you can see in Figure 8.12 "Results From Godden and
Baddeley, 1975", the divers’ memory was better when they were tested in the same context in
which they had learned the words than when they were tested in the other context.
Figure 8.12 Results From Godden and Baddeley, 1975
Godden and Baddeley (1975) tested the memory of scuba divers to learn and retrieve information in different
contexts and found strong evidence for context-dependent learning.
Source: Adapted from Godden, D. R., & Baddeley, A. D. (1975). Context-dependent memory in two natural
environments: On land and underwater.British Journal of Psychology, 66(3), 325–331.
You can see that context-dependent learning might also be important in improving your memory.
For instance, you might want to try to study for an exam in a situation that is similar to the one in
which you are going to take the exam.
Whereas context-dependent learning refers to a match in the external situation between learning
and remembering, state-dependent learning refers to superior retrieval of memories when the
individual is in the same physiological or psychological state as during encoding. Research has
found, for instance, that animals that learn a maze while under the influence of one drug tend to
remember their learning better when they are tested under the influence of the same drug than
when they are tested without the drug (Jackson, Koek, & Colpaert, 1992). [8]
And research with
humans finds that bilinguals remember better when tested in the same language in which they
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learned the material (Marian & Kaushanskaya, 2007). [9]
Mood states may also produce state-
dependent learning. People who learn information when they are in a bad (rather than a good)
mood find it easier to recall these memories when they are tested while they are in a bad mood,
and vice versa. It is easier to recall unpleasant memories than pleasant ones when we’re sad, and
easier to recall pleasant memories than unpleasant ones when we’re happy (Bower, 1981; Eich,
2008). [10]
Variations in the ability to retrieve information are also seen in the serial position curve. When
we give people a list of words one at a time (e.g., on flashcards) and then ask them to recall
them, the results look something like those in Figure 8.13 "The Serial Position Curve". People
are able to retrieve more words that were presented to them at the beginning and the end of the
list than they are words that were presented in the middle of the list. This pattern, known as the
serial position curve, is caused by two retrieval phenomenon: The primacy effect refers to a
tendency to better remember stimuli that are presented early in a list. The recency effect refers
to the tendency to better remember stimuli that are presented later in a list.
Figure 8.13 The Serial Position Curve
The serial position curve is the result of both primacy effects and recency effects.
There are a number of explanations for primacy and recency effects, but one of them is in terms
of the effects of rehearsal on short-term and long-term memory (Baddeley, Eysenck, &
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Anderson, 2009). [11]
Because we can keep the last words that we learned in the presented list in
short-term memory by rehearsing them before the memory test begins, they are relatively easily
remembered. So the recency effect can be explained in terms of maintenance rehearsal in short-
term memory. And the primacy effect may also be due to rehearsal—when we hear the first word
in the list we start to rehearse it, making it more likely that it will be moved from short-term to
long-term memory. And the same is true for the other words that come early in the list. But for
the words in the middle of the list, this rehearsal becomes much harder, making them less likely
to be moved to LTM.
In some cases our existing memories influence our new learning. This may occur either in a
backward way or a forward way. Retroactive interferenceoccurs when learning something new
impairs our ability to retrieve information that was learned earlier. For example, if you have
learned to program in one computer language, and then you learn to program in another similar
one, you may start to make mistakes programming the first language that you never would have
made before you learned the new one. In this case the new memories work backward
(retroactively) to influence retrieval from memory that is already in place.
In contrast to retroactive interference, proactive interference works in a forward
direction. Proactive interference occurs when earlier learning impairs our ability to encode
information that we try to learn later. For example, if we have learned French as a second
language, this knowledge may make it more difficult, at least in some respects, to learn a third
language (say Spanish), which involves similar but not identical vocabulary.
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Figure 8.14 Proactive and Retroactive Interference
Retroactive and proactive interference can both influence memory.
The Structure of LTM: Categories, Prototypes, and Schemas
Memories that are stored in LTM are not isolated but rather are linked together into categories—
networks of associated memories that have features in common with each other. Forming
categories, and using categories to guide behavior, is a fundamental part of human nature.
Associated concepts within a category are connected through spreading activation, which occurs
when activating one element of a category activates other associated elements. For instance,
because tools are associated in a category, reminding people of the word ―screwdriver‖ will help
them remember the word ―wrench.‖ And, when people have learned lists of words that come
from different categories (e.g., as in Note 8.33 "Retrieval Demonstration"), they do not recall the
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information haphazardly. If they have just remembered the word ―wrench,‖ they are more likely
to remember the word ―screwdriver‖ next than they are to remember the word ―dahlia,‖ because
the words are organized in memory by category and because ―dahlia‖ is activated by spreading
activation from ―wrench‖ (Srull & Wyer, 1989). [12]
Some categories have defining features that must be true of all members of the category. For
instance, all members of the category ―triangles‖ have three sides, and all members of the
category ―birds‖ lay eggs. But most categories are not so well-defined; the members of the
category share some common features, but it is impossible to define which are or are not
members of the category. For instance, there is no clear definition of the category ―tool.‖ Some
examples of the category, such as a hammer and a wrench, are clearly and easily identified as
category members, whereas other members are not so obvious. Is an ironing board a tool? What
about a car?
Members of categories (even those with defining features) can be compared to the
category prototype, which is the member of the category that is most average or typical of the
category. Some category members are more prototypical of, or similar to, the category than
others. For instance, some category members (robins and sparrows) are highly prototypical of the
category ―birds,‖ whereas other category members (penguins and ostriches) are less prototypical.
We retrieve information that is prototypical of a category faster than we retrieve information that
is less prototypical (Rosch, 1975). [13]
Mental categories are sometimes referred to as schemas—patterns of knowledge in long-term
memory that help us organize information. We have schemas about objects (that a triangle has
three sides and may take on different angles), about people (that Sam is friendly, likes to golf,
and always wears sandals), about events (the particular steps involved in ordering a meal at a
restaurant), and about social groups (we call these group schemas stereotypes).
Schemas are important in part because they help us remember new information by providing an
organizational structure for it. Read the following paragraph (Bransford & Johnson,
1972) [14]
and then try to write down everything you can remember.
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The procedure is actually quite simple. First you arrange things into different groups. Of course,
one pile may be sufficient depending on how much there is to do. If you have to go somewhere
else due to lack of facilities, that is the next step; otherwise you are pretty well set. It is important
not to overdo things. That is, it is better to do too few things at once than too many. In the short
run this may not seem important, but complications can easily arise. A mistake can be expensive
as well. At first the whole procedure will seem complicated. Soon, however, it will become just
another facet of life. It is difficult to foresee any end to the necessity for this task in the
immediate future, but then one never can tell. After the procedure is completed, one arranges the
materials into different groups again. Then they can be put into their appropriate places.
Eventually they will be used once more and the whole cycle will then have to be repeated.
However, that is part of life.
It turns out that people’s memory for this information is quite poor, unless they have been told
ahead of time that the information describes ―doing the laundry,‖ in which case their memory for
the material is much better. This demonstration of the role of schemas in memory shows how our
existing knowledge can help us organize new information, and how this organization can
improve encoding, storage, and retrieval.
The Biology of Memory
Just as information is stored on digital media such as DVDs and flash drives, the information in
LTM must be stored in the brain. The ability to maintain information in LTM involves a gradual
strengthening of the connections among the neurons in the brain. When pathways in these neural
networks are frequently and repeatedly fired, the synapses become more efficient in
communicating with each other, and these changes create memory. This process, known as long-
term potentiation (LTP), refers to the strengthening of the synaptic connections between neurons
as result of frequent stimulation (Lynch, 2002). [15]
Drugs that block LTP reduce learning,
whereas drugs that enhance LTP increase learning (Lynch et al., 1991). [16]
Because the new
patterns of activation in the synapses take time to develop, LTP happens gradually. The period of
time in which LTP occurs and in which memories are stored is known as the period
of consolidation.
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Memory is not confined to the cortex; it occurs through sophisticated interactions between new
and old brain structures (Figure 8.17 "Schematic Image of Brain With Hippocampus, Amygdala,
and Cerebellum Highlighted"). One of the most important brain regions in explicit memory is the
hippocampus, which serves as a preprocessor and elaborator of information (Squire,
1992). [17]
The hippocampus helps us encode information about spatial relationships, the context
in which events were experienced, and the associations among memories (Eichenbaum,
1999). [18]
The hippocampus also serves in part as a switching point that holds the memory for a
short time and then directs the information to other parts of the brain, such as the cortex, to
actually do the rehearsing, elaboration, and long-term storage (Jonides, Lacey, & Nee,
2005). [19]
Without the hippocampus, which might be described as the brain’s ―librarian,‖ our
explicit memories would be inefficient and disorganized.
Figure 8.17 Schematic Image of Brain With Hippocampus, Amygdala, and Cerebellum Highlighted
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Different brain structures help us remember different types of information. The hippocampus is particularly
important in explicit memories, the cerebellum is particularly important in implicit memories, and the amygdala is
particularly important in emotional memories.
While the hippocampus is handling explicit memory, the cerebellum and the amygdala are
concentrating on implicit and emotional memories, respectively. Research shows that the
cerebellum is more active when we are learning associations and in priming tasks, and animals
and humans with damage to the cerebellum have more difficulty in classical conditioning studies
(Krupa, Thompson, & Thompson, 1993; Woodruff-Pak, Goldenberg, Downey-Lamb, Boyko, &
Lemieux, 2000). [20]
The storage of many of our most important emotional memories, and
particularly those related to fear, is initiated and controlled by the amygdala (Sigurdsson,
Doyère, Cain, & LeDoux, 2007). [21]
Evidence for the role of different brain structures in different types of memories comes in part
from case studies of patients who suffer from amnesia, a memory disorder that involves the
inability to remember information. As with memory interference effects, amnesia can work in
either a forward or a backward direction, affecting retrieval or encoding. For people who suffer
damage to the brain, for instance, as a result of a stroke or other trauma, the amnesia may work
backward. The outcome is retrograde amnesia, a memory disorder that produces an inability to
retrieve events that occurred before a given time. Demonstrating the fact that LTP takes time
(the process of consolidation), retrograde amnesia is usually more severe for memories that
occurred just prior to the trauma than it is for older memories, and events that occurred just
before the event that caused memory loss may never be recovered because they were never
completely encoded.
Organisms with damage to the hippocampus develop a type of amnesia that works in a forward
direction to affect encoding, known as anterograde amnesia. Anterograde amnesia is the
inability to transfer information from short-term into long-term memory, making it impossible to
form new memories. One well-known case study was a man named Henry Gustav Molaison
(before he died in 2008, he was referred to only as H. M.) who had parts of his hippocampus
removed to reduce severe seizures (Corkin, Amaral, González, Johnson, & Hyman,
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1997). [22]
Following the operation, Molaison developed virtually complete anterograde amnesia.
Although he could remember most of what had happened before the operation, and particularly
what had occurred early in his life, he could no longer create new memories. Molaison was said
to have read the same magazines over and over again without any awareness of having seen them
before.
Cases of anterograde amnesia also provide information about the brain structures involved in
different types of memory (Bayley & Squire, 2005; Helmuth, 1999; Paller, 2004). [23]
Although
Molaison’s explicit memory was compromised because his hippocampus was damaged, his
implicit memory was not (because his cerebellum was intact). He could learn to trace shapes in a
mirror, a task that requires procedural memory, but he never had any explicit recollection of
having performed this task or of the people who administered the test to him.
Although some brain structures are particularly important in memory, this does not mean that all
memories are stored in one place. The American psychologist Karl Lashley (1929) [24]
attempted
to determine where memories were stored in the brain by teaching rats how to run mazes, and
then lesioning different brain structures to see if they were still able to complete the maze. This
idea seemed straightforward, and Lashley expected to find that memory was stored in certain
parts of the brain. But he discovered that no matter where he removed brain tissue, the rats
retained at least some memory of the maze, leading him to conclude that memory isn’t located in
a single place in the brain, but rather is distributed around it.
Long-term potentiation occurs as a result of changes in the synapses, which suggests that
chemicals, particularly neurotransmitters and hormones, must be involved in memory. There is
quite a bit of evidence that this is true.Glutamate, a neurotransmitter and a form of the amino
acid glutamic acid, is perhaps the most important neurotransmitter in memory (McEntee &
Crook, 1993). [25]
When animals, including people, are under stress, more glutamate is secreted,
and this glutamate can help them remember (McGaugh, 2003). [26]
The
neurotransmitter serotonin is also secreted when animals learn, andepinephrine may also
increase memory, particularly for stressful events (Maki & Resnick, 2000; Sherwin,
1998). [27]
Estrogen, a female sex hormone, also seems critical, because women who are
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experiencing menopause, along with a reduction in estrogen, frequently report memory
difficulties (Chester, 2001). [28]
Our knowledge of the role of biology in memory suggests that it might be possible to use drugs
to improve our memories, and Americans spend several hundred million dollars per year on
memory supplements with the hope of doing just that. Yet controlled studies comparing memory
enhancers, including Ritalin, methylphenidate, ginkgo biloba, and amphetamines, with placebo
drugs find very little evidence for their effectiveness (Gold, Cahill, & Wenk, 2002; McDaniel,
Maier, & Einstein, 2002). [29]
Memory supplements are usually no more effective than drinking a
sugared soft drink, which also releases glucose and thus improves memory slightly. This is not to
say that we cannot someday create drugs that will significantly improve our memory. It is likely
that this will occur in the future, but the implications of these advances are as yet unknown
(Farah et al., 2004; Turner & Sahakian, 2006). [30]
Although the most obvious potential use of drugs is to attempt to improve memory, drugs might
also be used to help us forget. This might be desirable in some cases, such as for those suffering
from posttraumatic stress disorder (PTSD) who are unable to forget disturbing memories.
Although there are no existing therapies that involve using drugs to help people forget, it is
possible that they will be available in the future. These possibilities will raise some important
ethical issues: Is it ethical to erase memories, and if it is, is it desirable to do so? Perhaps the
experience of emotional pain is a part of being a human being. And perhaps the experience of
emotional pain may help us cope with the trauma.
K E Y T A K E A W A Y S
Information is better remembered when it is meaningfully elaborated.
Hermann Ebbinghaus made important contributions to the study of learning, including modeling the forgetting curve,
and studying the spacing effect and the benefits of overlearning.
Context- and state-dependent learning, as well as primacy and recency effects, influence long-term memory.
Memories are stored in connected synapses through the process of long-term potentiation (LTP). In addition to the
cortex, other parts of the brain, including the hippocampus, cerebellum, and the amygdala, are also important in
memory.
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Damage to the brain may result in retrograde amnesia or anterograde amnesia. Case studies of patients with amnesia
can provide information about the brain structures involved in different types of memory.
Memory is influenced by chemicals including glutamate, serotonin, epinephrine, and estrogen.
Studies comparing memory enhancers with placebo drugs find very little evidence for their effectiveness.
E X E R C I S E S A N D C R I T I C A L T H I N K I N G
1. Plan a course of action to help you study for your next exam, incorporating as many of the techniques mentioned in
this section as possible. Try to implement the plan.
2. Make a list of some the schemas that you have stored in your memory. What are the contents of each schema, and
how might you use the schema to help you remember new information?
3. In the film “Eternal Sunshine of the Spotless Mind,” the characters undergo a medical procedure designed to erase
their memories of a painful romantic relationship. Would you engage in such a procedure if it was safely offered to
you?
[1] Nickerson, R. S., & Adams, M. J. (1979). Long-term memory for a common object.Cognitive Psychology, 11(3), 287–307.
[2] Craik, F. I., & Lockhart, R. S. (1972). Levels of processing: A framework for memory research. Journal of Verbal Learning &
Verbal Behavior, 11(6), 671–684; Harris, J. L., & Qualls, C. D. (2000). The association of elaborative or maintenance rehearsal
with age, reading comprehension and verbal working memory performance. Aphasiology, 14(5–6), 515–526.
[3] Rogers, T. B., Kuiper, N. A., & Kirker, W. S. (1977). Self-reference and the encoding of personal information. Journal of
Personality & Social Psychology, 35(9), 677–688.
[4] Symons, C. S., & Johnson, B. T. (1997). The self-reference effect in memory: A meta-analysis. Psychological Bulletin, 121(3),
371–394.
[5] Bahrick, H. P. (1984). Semantic memory content in permastore: Fifty years of memory for Spanish learned in school. Journal
of Experimental Psychology: General, 113(1), 1–29.
[6] Driskell, J. E., Willis, R. P., & Copper, C. (1992). Effect of overlearning on retention.Journal of Applied Psychology, 77(5), 615–
622.
[7] Godden, D. R., & Baddeley, A. D. (1975). Context-dependent memory in two natural environments: On land and
underwater. British Journal of Psychology, 66(3), 325–331.
[8] Jackson, A., Koek, W., & Colpaert, F. (1992). NMDA antagonists make learning and recall state-dependent. Behavioural
Pharmacology, 3(4), 415.
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[9] Marian, V. & Kaushanskaya, M. (2007). Language context guides memory content.Psychonomic Bulletin and Review, 14(5),
925–933.
[10] Bower, G. H. (1981). Mood and memory. American Psychologist, 36, 129–148; Eich, E. (2008). Mood and memory at 26:
Revisiting the idea of mood mediation in drug-dependent and place-dependent memory. In M. A. Gluck, J. R. Anderson, & S. M.
Kosslyn (Eds.),Memory and mind: A festschrift for Gordon H. Bower (pp. 247–260). Mahwah, NJ: Lawrence Erlbaum Associates.
[11] Baddeley, A., Eysenck, M. W., & Anderson, M. C. (2009). Memory. New York, NY: Psychology Press.
[12] Srull, T., & Wyer, R. (1989). Person memory and judgment. Psychological Review, 96(1), 58–83.
[13] Rosch, E. (1975). Cognitive representations of semantic categories. Journal of Experimental Psychology: General, 104(3),
192–233.
[14] Bransford, J. D., & Johnson, M. K. (1972). Contextual prerequisites for understanding: Some investigations of
comprehension and recall. Journal of Verbal Learning & Verbal Behavior, 11(6), 717–726.
[15] Lynch, G. (2002). Memory enhancement: The search for mechanism-based drugs.Nature Neuroscience, 5(Suppl.), 1035–
1038.
[16] Lynch, G., Larson, J., Staubli, U., Ambros-Ingerson, J., Granger, R., Lister, R. G.,…Weingartner, H. J. (1991). Long-term
potentiation and memory operations in cortical networks. In C. A. Wickliffe, M. Corballis, & G. White (Eds.), Perspectives on
cognitive neuroscience (pp. 110–131). New York, NY: Oxford University Press.
[17] Squire, L. R. (1992). Memory and the hippocampus: A synthesis from findings with rats, monkeys, and
humans. Psychological Review, 99(2), 195–231.
[18] Eichenbaum, H. (1999). Conscious awareness, memory, and the hippocampus. Nature Neuroscience, 2(9), 775–776.
[19] Jonides, J., Lacey, S. C., & Nee, D. E. (2005). Processes of working memory in mind and brain. Current Directions in
Psychological Science, 14(1), 2–5.
[20] Krupa, D. J., Thompson, J. K., & Thompson, R. F. (1993). Localization of a memory trace in the mammalian brain. Science,
260(5110), 989–991; Woodruff-Pak, D. S., Goldenberg, G., Downey-Lamb, M. M., Boyko, O. B., & Lemieux, S. K. (2000).
Cerebellar volume in humans related to magnitude of classical conditioning. Neuroreport: For Rapid Communication of
Neuroscience Research, 11(3), 609–615.
[21] Sigurdsson, T., Doyère, V., Cain, C. K., & LeDoux, J. E. (2007). Long-term potentiation in the amygdala: A cellular mechanism
of fear learning and memory. Neuropharmacology, 52(1), 215–227.
[22] Corkin, S., Amaral, D. G., González, R. G., Johnson, K. A., & Hyman, B. T. (1997). H. M.’s medial temporal lobe lesion:
Findings from magnetic resonance imaging. The Journal of Neuroscience, 17(10), 3964–3979.
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[23] Bayley, P. J., & Squire, L. R. (2005). Failure to acquire new semantic knowledge in patients with large medial temporal lobe
lesions. Hippocampus, 15(2), 273–280; Helmuth, Laura. (1999). New role found for the hippocampus. Science, 285, 1339–1341;
Paller, K. A. (2004). Electrical signals of memory and of the awareness of remembering. Current Directions in Psychological
Science, 13(2), 49–55.
[24] Lashley, K. S. (1929). The effects of cerebral lesions subsequent to the formation of the maze habit: Localization of the
habit. In Brain mechanisms and intelligence: A quantitative study of injuries to the brain (pp. 86–108). Chicago, IL: University of
Chicago Press.
[25] McEntee, W., & Crook, T. (1993). Glutamate: Its role in learning, memory, and the aging
brain. Psychopharmacology, 111(4), 391–401.
[26] McGaugh, J. L. (2003). Memory and emotion: The making of lasting memories. New York, NY: Columbia University Press.
[27] Maki, P. M., & Resnick, S. M. (2000). Longitudinal effects of estrogen replacement therapy on PET cerebral blood flow and
cognition. Neurobiology of Aging, 21, 373–383; Sherwin, B. B. (1998). Estrogen and cognitive functioning in
women. Proceedings of the Society for Experimental Biological Medicine, 217, 17–22.
[28] Chester, B. (2001). Restoring remembering: Hormones and memory. McGill Reporter, 33(10). Retrieved
from http://www.mcgill.ca/reporter/33/10/sherwin
[29] Gold, P. E., Cahill, L., & Wenk, G. L. (2002). Ginkgo biloba: A cognitive enhancer?Psychological Science in the Public Interest,
3(1), 2–11; McDaniel, M. A., Maier, S. F., & Einstein, G. O. (2002). “Brain-specific” nutrients: A memory cure? Psychological
Science in the Public Interest, 3(1), 12–38.
[30] Farah, M. J., Illes, J., Cook-Deegan, R., Gardner, H., Kandel, E., King, P.,…Wolpe, P. R. (2004). Neurocognitive enhancement:
What can we do and what should we do? Nature Reviews Neuroscience, 5(5), 421–425; Turner, D. C., & Sahakian, B. J. (2006).
Analysis of the cognitive enhancing effects of modafinil in schizophrenia. In J. L. Cummings (Ed.), Progress in neurotherapeutics
and neuropsychopharmacology (pp. 133–147). New York, NY: Cambridge University Press.
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8.3 Accuracy and Inaccuracy in Memory and Cognition L E A R N I N G O B J E C T I V E S
1. Outline the variables that can influence the accuracy of our memory for events.
2. Explain how schemas can distort our memories.
3. Describe the representativeness heuristic and the availability heuristic and explain how they may lead to errors in
judgment.
As we have seen, our memories are not perfect. They fail in part due to our inadequate encoding
and storage, and in part due to our inability to accurately retrieve stored information. But
memory is also influenced by the setting in which it occurs, by the events that occur to us after
we have experienced an event, and by the cognitive processes that we use to help us remember.
Although our cognition allows us to attend to, rehearse, and organize information, cognition may
also lead to distortions and errors in our judgments and our behaviors.
In this section we consider some of the cognitive biases that are known to influence
humans. Cognitive biases are errors in memory or judgment that are caused by the inappropriate
use of cognitive processes (Table 8.3 "Cognitive Processes That Pose Threats to Accuracy"). The
study of cognitive biases is important both because it relates to the important psychological
theme of accuracy versus inaccuracy in perception, and because being aware of the types of
errors that we may make can help us avoid them and therefore improve our decision-making
skills.
Table 8.3 Cognitive Processes That Pose Threats to Accuracy
Cognitive process Description Potential threat to accuracy
Source monitoring
The ability to accurately identify the source of a
memory
Uncertainty about the source of a memory may
lead to mistaken judgments.
Confirmation bias
The tendency to verify and confirm our existing
memories rather than to challenge and
disconfirm them
Once beliefs become established, they become
self-perpetuating and difficult to change.
Functional fixedness
When schemas prevent us from seeing and using
information in new and nontraditional ways
Creativity may be impaired by the overuse of
traditional, expectancy-based thinking.
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Cognitive process Description Potential threat to accuracy
Misinformation
effect
Errors in memory that occur when new but
incorrect information influences existing
accurate memories
Eyewitnesses who are questioned by the police
may change their memories of what they
observed at the crime scene.
Overconfidence
When we are more certain that our memories
and judgments are accurate than we should be
Eyewitnesses may be very confident that they
have accurately identified a suspect, even
though their memories are incorrect.
Salience
When some stimuli, (e.g., those that are colorful,
moving, or unexpected) grab our attention and
make them more likely to be remembered
We may base our judgments on a single salient
event while we ignore hundreds of other equally
informative events that we do not see.
Representativeness
heuristic
Tendency to make judgments according to how
well the event matches our expectations
After a coin has come up ―heads‖ many times in
a row, we may erroneously think that the next
flip is more likely to be ―tails‖ (the gambler’s
fallacy).
Availability heuristic
Idea that things that come to mind easily are
seen as more common
We may overestimate the crime statistics in our
own area, because these crimes are so easy to
recall.
Cognitive
accessibility
Idea that some memories are more highly
activated than others
We may think that we contributed more to a
project than we really did because it is so easy to
remember our own contributions.
Counterfactual
thinking
When we ―replay‖ events such that they turn out
differently (especially when only minor changes
in the events leading up to them make a
difference)
We may feel particularly bad about events that
might not have occurred if only a small change
had occurred before them.
Source Monitoring: Did It Really Happen?
One potential error in memory involves mistakes in differentiating the sources of
information. Source monitoring refers to the ability to accurately identify the source of a
memory. Perhaps you’ve had the experience of wondering whether you really experienced an
event or only dreamed or imagined it. If so, you wouldn’t be alone. Rassin, Merkelbach, and
Spaan (2001) [1]
reported that up to 25% of college students reported being confused about real
versus dreamed events. Studies suggest that people who are fantasy-prone are more likely to
experience source monitoring errors (Winograd, Peluso, & Glover, 1998), [2]
and such errors also
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occur more often for both children and the elderly than for adolescents and younger adults
(Jacoby & Rhodes, 2006). [3]
In other cases we may be sure that we remembered the information from real life but be
uncertain about exactly where we heard it. Imagine that you read a news story in a tabloid
magazine such as the National Enquirer. Probably you would have discounted the information
because you know that its source is unreliable. But what if later you were to remember the story
but forget the source of the information? If this happens, you might become convinced that the
news story is true because you forget to discount it. The sleeper effectrefers to attitude change
that occurs over time when we forget the source of information (Pratkanis, Greenwald, Leippe, &
Baumgardner, 1988). [4]
In still other cases we may forget where we learned information and mistakenly assume that we
created the memory ourselves. Kaavya Viswanathan, the author of the book How Opal Mehta
Got Kissed, Got Wild, and Got a Life, was accused of plagiarism when it was revealed that many
parts of her book were very similar to passages from other material. Viswanathan argued that she
had simply forgotten that she had read the other works, mistakenly assuming she had made up
the material herself. And the musician George Harrison claimed that he was unaware that the
melody of his song ―My Sweet Lord‖ was almost identical to an earlier song by another
composer. The judge in the copyright suit that followed ruled that Harrison didn’t intentionally
commit the plagiarism. (Please use this knowledge to become extra vigilant about source
attributions in your written work, not to try to excuse yourself if you are accused of plagiarism.)
Schematic Processing: Distortions Based on Expectations
We have seen that schemas help us remember information by organizing material into coherent
representations. However, although schemas can improve our memories, they may also lead to
cognitive biases. Using schemas may lead us to falsely remember things that never happened to
us and to distort or misremember things that did. For one, schemas lead to the confirmation bias,
which is the tendency to verify and confirm our existing memories rather than to challenge and
disconfirm them. The confirmation bias occurs because once we have schemas, they influence
how we seek out and interpret new information. The confirmation bias leads us to remember
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information that fits our schemas better than we remember information that disconfirms them
(Stangor & McMillan, 1992), [5]
a process that makes our stereotypes very difficult to change.
And we ask questions in ways that confirm our schemas (Trope & Thompson, 1997). [6]
If we
think that a person is an extrovert, we might ask her about ways that she likes to have fun,
thereby making it more likely that we will confirm our beliefs. In short, once we begin to believe
in something—for instance, a stereotype about a group of people—it becomes very difficult to
later convince us that these beliefs are not true; the beliefs become self-confirming.
Darley and Gross (1983) [7]
demonstrated how schemas about social class could influence
memory. In their research they gave participants a picture and some information about a fourth-
grade girl named Hannah. To activate a schema about her social class, Hannah was pictured
sitting in front of a nice suburban house for one-half of the participants and pictured in front of
an impoverished house in an urban area for the other half. Then the participants watched a video
that showed Hannah taking an intelligence test. As the test went on, Hannah got some of the
questions right and some of them wrong, but the number of correct and incorrect answers was
the same in both conditions. Then the participants were asked to remember how many questions
Hannah got right and wrong. Demonstrating that stereotypes had influenced memory, the
participants who thought that Hannah had come from an upper-class background remembered
that she had gotten more correct answers than those who thought she was from a lower-class
background.
Our reliance on schemas can also make it more difficult for us to ―think outside the box.‖ Peter
Wason (1960) [8]
asked college students to determine the rule that was used to generate the
numbers 2-4-6 by asking them to generate possible sequences and then telling them if those
numbers followed the rule. The first guess that students made was usually ―consecutive
ascending even numbers,‖ and they then asked questions designed to confirm their hypothesis
(―Does 102-104-106 fit?‖ ―What about 404-406-408?‖). Upon receiving information that those
guesses did fit the rule, the students stated that the rule was ―consecutive ascending even
numbers.‖ But the students’ use of the confirmation bias led them to ask only about instances
that confirmed their hypothesis, and not about those that would disconfirm it. They never
bothered to ask whether 1-2-3 or 3-11-200 would fit, and if they had they would have learned
that the rule was not ―consecutive ascending even numbers,‖ but simply ―any three ascending
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numbers.‖ Again, you can see that once we have a schema (in this case a hypothesis), we
continually retrieve that schema from memory rather than other relevant ones, leading us to act
in ways that tend to confirm our beliefs.
Functional fixedness occurs when people’s schemas prevent them from using an object in new
and nontraditional ways. Duncker (1945) [9]
gave participants a candle, a box of thumbtacks, and
a book of matches, and asked them to attach the candle to the wall so that it did not drip onto the
table below (Figure 8.19 "Functional Fixedness"). Few of the participants realized that the box
could be tacked to the wall and used as a platform to hold the candle. The problem again is that
our existing memories are powerful, and they bias the way we think about new information.
Because the participants were ―fixated‖ on the box’s normal function of holding thumbtacks,
they could not see its alternative use.
Figure 8.19 Functional Fixedness
In the candle-tack-box problem, functional fixedness may lead us to see the box only as a box and not as a potential
candleholder.
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Misinformation Effects: How Information That Comes Later Can Distort Memory
A particular problem for eyewitnesses such as Jennifer Thompson is that our memories are often
influenced by the things that occur to us after we have learned the information (Erdmann,
Volbert, & Böhm, 2004; Loftus, 1979; Zaragoza, Belli, & Payment, 2007). [10] This new
information can distort our original memories such that the we are no longer sure what is the real
information and what was provided later. The misinformation effect refers to errors in memory
that occur when new information influences existing memories.
In an experiment by Loftus and Palmer (1974), [11] participants viewed a film of a traffic
accident and then, according to random assignment to experimental conditions, answered one of
three questions:
―About how fast were the cars going when they hit each other?‖
―About how fast were the cars going when they smashed each other?‖
―About how fast were the cars going when they contacted each other?‖
As you can see in Figure 8.20 "Misinformation Effect", although all the participants saw the
same accident, their estimates of the cars’ speed varied by condition. Participants who had been
asked about the cars ―smashing‖ each other estimated the highest average speed, and those who
had been asked the ―contacted‖ question estimated the lowest average speed.
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Figure 8.20 Misinformation Effect
Participants viewed a film of a traffic accident and then answered a question about the accident. According to
random assignment, the verb in the question was filled by either ―hit,‖ ―smashed,‖ or ―contacted‖ each other. The
wording of the question influenced the participants’ memory of the accident.
Source: Adapted from Loftus, E. F., & Palmer, J. C. (1974). Reconstruction of automobile destruction: An example of
the interaction between language and memory. Journal of Verbal Learning & Verbal Behavior, 13(5), 585–589.
In addition to distorting our memories for events that have actually occurred, misinformation
may lead us to falsely remember information that never occurred. Loftus and her colleagues
asked parents to provide them with descriptions of events that did (e.g., moving to a new house)
and did not (e.g., being lost in a shopping mall) happen to their children. Then (without telling
the children which events were real or made-up) the researchers asked the children to imagine
both types of events. The children were instructed to ―think real hard‖ about whether the events
had occurred (Ceci, Huffman, Smith, & Loftus, 1994). [12]
More than half of the children
generated stories regarding at least one of the made-up events, and they remained insistent that
the events did in fact occur even when told by the researcher that they could not possibly have
occurred (Loftus & Pickrell, 1995). [13]
Even college students are susceptible to manipulations
that make events that did not actually occur seem as if they did (Mazzoni, Loftus, & Kirsch,
2001). [14]
The ease with which memories can be created or implanted is particularly problematic when the
events to be recalled have important consequences. Therapists often argue that patients may
repress memories of traumatic events they experienced as children, such as childhood sexual
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abuse, and then recover the events years later as the therapist leads them to recall the
information—for instance, by using dream interpretation and hypnosis (Brown, Scheflin, &
Hammond, 1998). [15]
But other researchers argue that painful memories such as sexual abuse are usually very well
remembered, that few memories are actually repressed, and that even if they are it is virtually
impossible for patients to accurately retrieve them years later (McNally, Bryant, & Ehlers, 2003;
Pope, Poliakoff, Parker, Boynes, & Hudson, 2007). [16]
These researchers have argued that the
procedures used by the therapists to ―retrieve‖ the memories are more likely to actually implant
false memories, leading the patients to erroneously recall events that did not actually occur.
Because hundreds of people have been accused, and even imprisoned, on the basis of claims
about ―recovered memory‖ of child sexual abuse, the accuracy of these memories has important
societal implications. Many psychologists now believe that most of these claims of recovered
memories are due to implanted, rather than real, memories (Loftus & Ketcham, 1994). [17]
Overconfidence
One of the most remarkable aspects of Jennifer Thompson’s mistaken identity of Ronald Cotton
was her certainty. But research reveals a pervasive cognitive bias toward overconfidence, which
is the tendency for people to be too certain about their ability to accurately remember events and
to make judgments. David Dunning and his colleagues (Dunning, Griffin, Milojkovic, & Ross,
1990) [18]
asked college students to predict how another student would react in various situations.
Some participants made predictions about a fellow student whom they had just met and
interviewed, and others made predictions about their roommates whom they knew very well. In
both cases, participants reported their confidence in each prediction, and accuracy was
determined by the responses of the people themselves. The results were clear: Regardless of
whether they judged a stranger or a roommate, the participants consistently overestimated the
accuracy of their own predictions.
Eyewitnesses to crimes are also frequently overconfident in their memories, and there is only a
small correlation between how accurate and how confident an eyewitness is. The witness who
claims to be absolutely certain about his or her identification (e.g., Jennifer Thompson) is not
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much more likely to be accurate than one who appears much less sure, making it almost
impossible to determine whether a particular witness is accurate or not (Wells & Olson,
2003). [19]
I am sure that you have a clear memory of when you first heard about the 9/11 attacks in 2001,
and perhaps also when you heard that Princess Diana was killed in 1997 or when the verdict of
the O. J. Simpson trial was announced in 1995. This type of memory, which we experience along
with a great deal of emotion, is known as a flashbulb memory—a vivid and emotional memory of
an unusual event that people believe they remember very well. (Brown & Kulik, 1977). [20]
People are very certain of their memories of these important events, and frequently
overconfident. Talarico and Rubin (2003) [21]
tested the accuracy of flashbulb memories by
asking students to write down their memory of how they had heard the news about either the
September 11, 2001, terrorist attacks or about an everyday event that had occurred to them
during the same time frame. These recordings were made on September 12, 2001. Then the
participants were asked again, either 1, 6, or 32 weeks later, to recall their memories. The
participants became less accurate in their recollections of both the emotional event and the
everyday events over time. But the participants’ confidence in the accuracy of their memory of
learning about the attacks did not decline over time. After 32 weeks the participants were
overconfident; they were much more certain about the accuracy of their flashbulb memories than
they should have been. Schmolck, Buffalo, and Squire (2000) [22]
found similar distortions in
memories of news about the verdict in the O. J. Simpson trial.
Heuristic Processing: Availability and Representativeness
Another way that our information processing may be biased occurs when we use heuristics,
which are information-processing strategies that are useful in many cases but may lead to errors
when misapplied. Let’s consider two of the most frequently applied (and misapplied) heuristics:
the representativeness heuristic and the availability heuristic.
In many cases we base our judgments on information that seems to represent, or match, what we
expect will happen, while ignoring other potentially more relevant statistical information. When
we do so, we are using the representativeness heuristic. Consider, for instance, the puzzle
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presented in Table 8.4 "The Representativeness Heuristic". Let’s say that you went to a hospital,
and you checked the records of the babies that were born today. Which pattern of births do you
think you are most likely to find?
Table 8.4 The Representativeness Heuristic
List A List B
6:31 a.m. Girl 6:31 a.m. Boy
8:15 a.m. Girl 8:15 a.m. Girl
9:42 a.m. Girl 9:42 a.m. Boy
1:13 p.m. Girl 1:13 p.m. Girl
3:39 p.m. Boy 3:39 p.m. Girl
5:12 p.m. Boy 5:12 p.m. Boy
7:42 p.m. Boy 7:42 p.m. Girl
11:44 p.m. Boy 11:44 p.m. Boy
Using the representativeness heuristic may lead us to incorrectly believe that some patterns of observed events are
more likely to have occurred than others. In this case, list B seems more random, and thus is judged as more likely
to have occurred, but statistically both lists are equally likely.
Most people think that list B is more likely, probably because list B looks more random, and thus
matches (is ―representative of‖) our ideas about randomness. But statisticians know that any
pattern of four girls and four boys is mathematically equally likely. The problem is that we have
a schema of what randomness should be like, which doesn’t always match what is
mathematically the case. Similarly, people who see a flipped coin come up ―heads‖ five times in
a row will frequently predict, and perhaps even wager money, that ―tails‖ will be next. This
behavior is known as the gambler’s fallacy. But mathematically, the gambler’s fallacy is an
error: The likelihood of any single coin flip being ―tails‖ is always 50%, regardless of how many
times it has come up ―heads‖ in the past.
Our judgments can also be influenced by how easy it is to retrieve a memory. The tendency to
make judgments of the frequency or likelihood that an event occurs on the basis of the ease with
which it can be retrieved from memory is known as the availability heuristic (MacLeod &
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Campbell, 1992; Tversky & Kahneman, 1973). [23]
Imagine, for instance, that I asked you to
indicate whether there are more words in the English language that begin with the letter ―R‖ or
that have the letter ―R‖ as the third letter. You would probably answer this question by trying to
think of words that have each of the characteristics, thinking of all the words you know that
begin with ―R‖ and all that have ―R‖ in the third position. Because it is much easier to retrieve
words by their first letter than by their third, we may incorrectly guess that there are more words
that begin with ―R,‖ even though there are in fact more words that have ―R‖ as the third letter.
The availability heuristic may also operate on episodic memory. We may think that our friends
are nice people, because we see and remember them primarily when they are around us (their
friends, who they are, of course, nice to). And the traffic might seem worse in our own
neighborhood than we think it is in other places, in part because nearby traffic jams are more
easily retrieved than are traffic jams that occur somewhere else.
Salience and Cognitive Accessibility
Still another potential for bias in memory occurs because we are more likely to attend to, and
thus make use of and remember, some information more than other information. For one, we
tend to attend to and remember things that are highly salient, meaning that they attract our
attention. Things that are unique, colorful, bright, moving, and unexpected are more salient
(McArthur & Post, 1977; Taylor & Fiske, 1978). [24]
In one relevant study, Loftus, Loftus, and
Messo (1987) [25]
showed people images of a customer walking up to a bank teller and pulling
out either a pistol or a checkbook. By tracking eye movements, the researchers determined that
people were more likely to look at the gun than at the checkbook, and that this reduced their
ability to accurately identify the criminal in a lineup that was given later. The salience of the gun
drew people’s attention away from the face of the criminal.
The salience of the stimuli in our social worlds has a big influence on our judgment, and in some
cases may lead us to behave in ways that we might better not have. Imagine, for instance, that
you wanted to buy a new music player for yourself. You’ve been trying to decide whether to get
the iPod or the Zune. You checked Consumer Reports online and found that, although the
players differed on many dimensions, including price, battery life, ability to share music, and so
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forth, the Zune was nevertheless rated significantly higher by owners than was the iPod. As a
result, you decide to purchase the Zune the next day. That night, however, you go to a party, and
a friend shows you her iPod. You check it out, and it seems really cool. You tell her that you
were thinking of buying a Zune, and she tells you that you are crazy. She says she knows
someone who had one and it had a lot of problems—it didn’t download music correctly, the
battery died right after the warranty expired, and so forth—and that she would never buy one.
Would you still buy the Zune, or would you switch your plans?
If you think about this question logically, the information that you just got from your friend isn’t
really all that important. You now know the opinion of one more person, but that can’t change
the overall rating of the two machines very much. On the other hand, the information your friend
gives you, and the chance to use her iPod, are highly salient. The information is right there in
front of you, in your hand, whereas the statistical information from Consumer Reports is only in
the form of a table that you saw on your computer. The outcome in cases such as this is that
people frequently ignore the less salient but more important information, such as the likelihood
that events occur across a large population (these statistics are known as base rates), in favor of
the less important but nevertheless more salient information.
People also vary in the schemas that they find important to use when judging others and when
thinking about themselves. Cognitive accessibility refers tothe extent to which knowledge is
activated in memory, and thus likely to be used in cognition and behavior. For instance, you
probably know a person who is a golf nut (or fanatic of another sport). All he can talk about is
golf. For him, we would say that golf is a highly accessible construct. Because he loves golf, it is
important to his self-concept, he sets many of his goals in terms of the sport, and he tends to
think about things and people in terms of it (―if he plays golf, he must be a good person!‖). Other
people have highly accessible schemas about environmental issues, eating healthy food, or
drinking really good coffee. When schemas are highly accessible, we are likely to use them to
make judgments of ourselves and others, and this overuse may inappropriately color our
judgments.
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Counterfactual Thinking
In addition to influencing our judgments about ourselves and others, the ease with which we can
retrieve potential experiences from memory can have an important effect on our own emotions.
If we can easily imagine an outcome that is better than what actually happened, then we may
experience sadness and disappointment; on the other hand, if we can easily imagine that a result
might have been worse than what actually happened, we may be more likely to experience
happiness and satisfaction. The tendency to think about and experience events according to
“what might have been” is known ascounterfactual thinking (Kahneman & Miller, 1986; Roese,
2005). [26]
Imagine, for instance, that you were participating in an important contest, and you won the silver
(second-place) medal. How would you feel? Certainly you would be happy that you won the
silver medal, but wouldn’t you also be thinking about what might have happened if you had been
just a little bit better—you might have won the gold medal! On the other hand, how might you
feel if you won the bronze (third-place) medal? If you were thinking about the
counterfactuals (the ―what might have beens‖) perhaps the idea of not getting any medal at all
would have been highly accessible; you’d be happy that you got the medal that you did get,
rather than coming in fourth.
Tom Gilovich and his colleagues (Medvec, Madey, & Gilovich, 1995) [28]
investigated this idea
by videotaping the responses of athletes who won medals in the 1992 Summer Olympic Games.
They videotaped the athletes both as they learned that they had won a silver or a bronze medal
and again as they were awarded the medal. Then the researchers showed these videos, without
any sound, to raters who did not know which medal which athlete had won. The raters were
asked to indicate how they thought the athlete was feeling, using a range of feelings from
―agony‖ to ―ecstasy.‖ The results showed that the bronze medalists were, on average, rated as
happier than were the silver medalists. In a follow-up study, raters watched interviews with many
of these same athletes as they talked about their performance. The raters indicated what we
would expect on the basis of counterfactual thinking—the silver medalists talked about their
disappointments in having finished second rather than first, whereas the bronze medalists
focused on how happy they were to have finished third rather than fourth.
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You might have experienced counterfactual thinking in other situations. Once I was driving
across country, and my car was having some engine trouble. I really wanted to make it home
when I got near the end of my journey; I would have been extremely disappointed if the car
broke down only a few miles from my home. Perhaps you have noticed that once you get close
to finishing something, you feel like you really need to get it done. Counterfactual thinking has
even been observed in juries. Jurors who were asked to award monetary damages to others who
had been in an accident offered them substantially more in compensation if they barely avoided
injury than they offered if the accident seemed inevitable (Miller, Turnbull, & McFarland,
1988). [29]
Psychology in Everyday Life: Cognitive Biases in the Real World
Perhaps you are thinking that the kinds of errors that we have been talking about don’t seem that important. After all,
who really cares if we think there are more words that begin with the letter “R” than there actually are, or if bronze
medal winners are happier than the silver medalists? These aren’t big problems in the overall scheme of things. But it
turns out that what seem to be relatively small cognitive biases on the surface can have profound consequences for
people.
Why would so many people continue to purchase lottery tickets, buy risky investments in the stock market, or gamble
their money in casinos when the likelihood of them ever winning is so low? One possibility is that they are victims of
salience; they focus their attention on the salient likelihood of a big win, forgetting that the base rate of the event
occurring is very low. The belief in astrology, which all scientific evidence suggests is not accurate, is probably driven
in part by the salience of the occasions when the predictions are correct. When a horoscope comes true (which will, of
course, happen sometimes), the correct prediction is highly salient and may allow people to maintain the overall false
belief.
People may also take more care to prepare for unlikely events than for more likely ones, because the unlikely ones are
more salient. For instance, people may think that they are more likely to die from a terrorist attack or a homicide than
they are from diabetes, stroke, or tuberculosis. But the odds are much greater of dying from the latter than the former.
And people are frequently more afraid of flying than driving, although the likelihood of dying in a car crash is
hundreds of times greater than dying in a plane crash (more than 50,000 people are killed on U.S. highways every
year). Because people don’t accurately calibrate their behaviors to match the true potential risks (e.g., they drink and
drive or don’t wear their seatbelts), the individual and societal level costs are often quite large (Slovic, 2000). [30]
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Salience and accessibility also color how we perceive our social worlds, which may have a big influence on our
behavior. For instance, people who watch a lot of violent television shows also view the world as more dangerous
(Doob & Macdonald, 1979), [31]
probably because violence becomes more cognitively accessible for them. We also
unfairly overestimate our contribution to joint projects (Ross & Sicoly, 1979), [32]
perhaps in part because our own
contributions are highly accessible, whereas the contributions of others are much less so.
Even people who should know better, and who need to know better, are subject to cognitive biases. Economists, stock
traders, managers, lawyers, and even doctors make the same kinds of mistakes in their professional activities that
people make in their everyday lives (Gilovich, Griffin, & Kahneman, 2002). [33]
Just like us, these people are victims of
overconfidence, heuristics, and other biases.
Furthermore, every year thousands of individuals, such as Ronald Cotton, are charged with and often convicted of
crimes based largely on eyewitness evidence. When eyewitnesses testify in courtrooms regarding their memories of a
crime, they often are completely sure that they are identifying the right person. But the most common cause of
innocent people being falsely convicted is erroneous eyewitness testimony (Wells, Wright, & Bradfield, 1999). [34]
The
many people who were convicted by mistaken eyewitnesses prior to the advent of forensic DNA and who have now
been exonerated by DNA tests have certainly paid for all-too-common memory errors (Wells, Memon, & Penrod,
2006). [35]
Although cognitive biases are common, they are not impossible to control, and psychologists and other scientists are
working to help people make better decisions. One possibility is to provide people with better feedback about their
judgments. Weather forecasters, for instance, learn to be quite accurate in their judgments because they have clear
feedback about the accuracy of their predictions. Other research has found that accessibility biases can be reduced by
leading people to consider multiple alternatives rather than focus only on the most obvious ones, and particularly by
leading people to think about opposite possible outcomes than the ones they are expecting (Lilienfeld, Ammirtai, &
Landfield, 2009). [36]
Forensic psychologists are also working to reduce the incidence of false identification by helping
police develop better procedures for interviewing both suspects and eyewitnesses (Steblay, Dysart, Fulero, & Lindsay,
2001). [37]
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K E Y T A K E A W A Y S
Our memories fail in part due to inadequate encoding and storage, and in part due to the inability to accurately
retrieve stored information.
The human brain is wired to develop and make use of social categories and schemas. Schemas help us remember new
information but may also lead us to falsely remember things that never happened to us and to distort or
misremember things that did.
A variety of cognitive biases influence the accuracy of our judgments.
E X E R C I S E S A N D C R I T I C A L T H I N K I N G
1. Consider a time when you were uncertain if you really experienced an event or only imagined it. What impact did this
have on you, and how did you resolve it?
2. Consider again some of the cognitive schemas that you hold in your memory. How do these knowledge structures bias
your information processing and behavior, and how might you prevent them from doing so?
3. Imagine that you were involved in a legal case in which an eyewitness claimed that he had seen a person commit a
crime. Based on your knowledge about memory and cognition, what techniques would you use to reduce the
possibility that the eyewitness was making a mistaken identification?
[1] Rassin, E., Merckelbach, H., & Spaan, V. (2001). When dreams become a royal road to confusion: Realistic dreams,
dissociation, and fantasy proneness. Journal of Nervous and Mental Disease, 189(7), 478–481.
[2] Winograd, E., Peluso, J. P., & Glover, T. A. (1998). Individual differences in susceptibility to memory illusions. Applied
Cognitive Psychology, 12(Spec. Issue), S5–S27.
[3] Jacoby, L. L., & Rhodes, M. G. (2006). False remembering in the aged. Current Directions in Psychological Science, 15(2), 49–
53.
[4] Pratkanis, A. R., Greenwald, A. G., Leippe, M. R., & Baumgardner, M. H. (1988). In search of reliable persuasion effects: III.
The sleeper effect is dead: Long live the sleeper effect.Journal of Personality and Social Psychology, 54(2), 203–218.
[5] Stangor, C., & McMillan, D. (1992). Memory for expectancy-congruent and expectancy-incongruent information: A review of
the social and social developmental literatures.Psychological Bulletin, 111(1), 42–61.
[6] Trope, Y., & Thompson, E. (1997). Looking for truth in all the wrong places? Asymmetric search of individuating information
about stereotyped group members. Journal of Personality and Social Psychology, 73, 229–241.
[7] Darley, J. M., & Gross, P. H. (1983). A hypothesis-confirming bias in labeling effects.Journal of Personality and Social
Psychology, 44, 20–33.
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[8] Wason, P. (1960). On the failure to eliminate hypotheses in a conceptual task. The Quarterly Journal of Experimental
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[9] Duncker, K. (1945). On problem-solving. Psychological Monographs, 58, 5.
[10] Erdmann, K., Volbert, R., & Böhm, C. (2004). Children report suggested events even when interviewed in a non-suggestive
manner: What are its implications for credibility assessment? Applied Cognitive Psychology, 18(5), 589–611; Loftus, E. F. (1979).
The malleability of human memory. American Scientist, 67(3), 312–320; Zaragoza, M. S., Belli, R. F., & Payment, K. E. (2007).
Misinformation effects and the suggestibility of eyewitness memory. In M. Garry & H. Hayne (Eds.), Do justice and let the sky
fall: Elizabeth Loftus and her contributions to science, law, and academic freedom (pp. 35–63). Mahwah, NJ: Lawrence Erlbaum
Associates.
[11] Loftus, E. F., & Palmer, J. C. (1974). Reconstruction of automobile destruction: An example of the interaction between
language and memory. Journal of Verbal Learning & Verbal Behavior, 13(5), 585–589.
[12] Ceci, S. J., Huffman, M. L. C., Smith, E., & Loftus, E. F. (1994). Repeatedly thinking about a non-event: Source
misattributions among preschoolers. Consciousness and Cognition: An International Journal, 3(3–4), 388–407.
[13] Loftus, E. F., & Pickrell, J. E. (1995). The formation of false memories. Psychiatric Annals, 25(12), 720–725.
[14] Mazzoni, G. A. L., Loftus, E. F., & Kirsch, I. (2001). Changing beliefs about implausible autobiographical events: A little
plausibility goes a long way. Journal of Experimental Psychology: Applied, 7(1), 51–59.
[15] Brown, D., Scheflin, A. W., & Hammond, D. C. (1998). Memory, trauma treatment, and the law. New York, NY: Norton.
[16] McNally, R. J., Bryant, R. A., & Ehlers, A. (2003). Does early psychological intervention promote recovery from
posttraumatic stress? Psychological Science in the Public Interest, 4(2), 45–79; Pope, H. G., Jr., Poliakoff, M. B., Parker, M. P.,
Boynes, M., & Hudson, J. I. (2007). Is dissociative amnesia a culture-bound syndrome? Findings from a survey of historical
literature. Psychological Medicine: A Journal of Research in Psychiatry and the Allied Sciences, 37(2), 225–233.
[17] Loftus, E. F., & Ketcham, K. (1994). The myth of repressed memory: False memories and allegations of sexual abuse (1st
ed.). New York, NY: St. Martin’s Press.
[18] Dunning, D., Griffin, D. W., Milojkovic, J. D., & Ross, L. (1990). The overconfidence effect in social prediction. Journal of
Personality and Social Psychology, 58(4), 568–581.
[19] Wells, G. L., & Olson, E. A. (2003). Eyewitness testimony. Annual Review of Psychology, 277–295.
[20] Brown, R., & Kulik, J. (1977). Flashbulb memories. Cognition, 5, 73–98.
[21] Talarico, J. M., & Rubin, D. C. (2003). Confidence, not consistency, characterizes flashbulb memories. Psychological Science,
14(5), 455–461.
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[22] Schmolck, H., Buffalo, E. A., & Squire, L. R. (2000). Memory distortions develop over time: Recollections of the O. J.
Simpson trial verdict after 15 and 32 months. Psychological Science, 11(1), 39–45.
[23] MacLeod, C., & Campbell, L. (1992). Memory accessibility and probability judgments: An experimental evaluation of the
availability heuristic. Journal of Personality and Social Psychology, 63(6), 890–902; Tversky, A., & Kahneman, D. (1973).
Availability: A heuristic for judging frequency and probability. Cognitive Psychology, 5, 207–232.
[24] McArthur, L. Z., & Post, D. L. (1977). Figural emphasis and person perception. Journal of Experimental Social Psychology,
13(6), 520–535; Taylor, S. E., & Fiske, S. T. (1978). Salience, attention and attribution: Top of the head phenomena. Advances in
Experimental Social Psychology, 11, 249–288.
[25] Loftus, E. F., Loftus, G. R., & Messo, J. (1987). Some facts about “weapon focus.” Law and Human Behavior, 11(1), 55–62.
[26] Kahneman, D., & Miller, D. T. (1986). Norm theory: Comparing reality to its alternatives. Psychological Review, 93, 136–
153; Roese, N. (2005). If only: How to turn regret into opportunity. New York, NY: Broadway Books.
[27] Medvec, V. H., Madey, S. F., & Gilovich, T. (1995). When less is more: Counterfactual thinking and satisfaction among
Olympic medalists. Journal of Personality & Social Psychology, 69(4), 603–610.
[28] Medvec, V. H., Madey, S. F., & Gilovich, T. (1995). When less is more: Counterfactual thinking and satisfaction among
Olympic medalists. Journal of Personality & Social Psychology, 69(4), 603–610.
[29] Miller, D. T., Turnbull, W., & McFarland, C. (1988). Particularistic and universalistic evaluation in the social comparison
process. Journal of Personality and Social Psychology, 55, 908–917.
[30] Slovic, P. (Ed.). (2000). The perception of risk. London, England: Earthscan Publications.
[31] Doob, A. N., & Macdonald, G. E. (1979). Television viewing and fear of victimization: Is the relationship causal? Journal of
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[32] Ross, M., & Sicoly, F. (1979). Egocentric biases in availability and attribution. Journal of Personality and Social Psychology,
37(3), 322–336.
[33] Gilovich, T., Griffin, D., & Kahneman, D. (2002). Heuristics and biases: The psychology of intuitive judgment. New York, NY:
Cambridge University Press.
[34] Wells, G. L., Wright, E. F., & Bradfield, A. L. (1999). Witnesses to crime: Social and cognitive factors governing the validity of
people’s reports. In R. Roesch, S. D. Hart, & J. R. P. Ogloff (Eds.), Psychology and law: The state of the discipline (pp. 53–87).
Dordrecht, Netherlands: Kluwer Academic Publishers.
[35] Wells, G. L., Memon, A., & Penrod, S. D. (2006). Eyewitness evidence: Improving its probative value. Psychological Science
in the Public Interest, 7(2), 45–75.
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[36] Lilienfeld, S. O., Ammirati, R., & Landfield, K. (2009). Giving debiasing away: Can psychological research on correcting
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[37] Steblay, N., Dysart, J., Fulero, S., & Lindsay, R. C. L. (2001). Eyewitness accuracy rates in sequential and simultaneous lineup
presentations: A meta-analytic comparison. Law and Human Behavior, 25(5), 459–473.
8.4 Chapter Summary
Memory and cognition are the two major interests of cognitive psychologists. The cognitive
school was influenced in large part by the development of the electronic computer. Psychologists
conceptualize memory in terms of types, stages, and processes.
Explicit memory is assessed using measures in which the individual being tested must
consciously attempt to remember the information. Explicit memory includes semantic and
episodic memory. Explicit memory tests include recall memory tests, recognition memory tests,
and measures of relearning (also known as savings).
Implicit memory refers to the influence of experience on behavior, even if the individual is not
aware of those influences. Implicit memory is made up of procedural memory, classical
conditioning effects, and priming. Priming refers both to the activation of knowledge and to the
influence of that activation on behavior. An important characteristic of implicit memories is that
they are frequently formed and used automatically, without much effort or awareness on our part.
Sensory memory, including iconic and echoic memory, is a memory buffer that lasts only very
briefly and then, unless it is attended to and passed on for more processing, is forgotten.
Information that we turn our attention to may move into short-term memory (STM). STM is
limited in both the length and the amount of information it can hold. Working memory is a set of
memory procedures or operations that operates on the information in STM. Working memory’s
central executive directs the strategies used to keep information in STM, such as maintenance
rehearsal, visualization, and chunking.
Long-term memory (LTM) is memory storage that can hold information for days, months, and
years. The information that we want to remember in LTM must be encoded and stored, and then
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retrieved. Some strategies for improving LTM include elaborative encoding, relating information
to the self, making use of the forgetting curve and the spacing effect, overlearning, and being
aware of context- and state-dependent retrieval effects.
Memories that are stored in LTM are not isolated but rather are linked together into categories
and schemas. Schemas are important in part because they help us encode and retrieve
information by providing an organizational structure for it.
The ability to maintain information in LTM involves a gradual strengthening of the connections
among the neurons in the brain, known as long-term potentiation (LTP). The hippocampus is
important in explicit memory, the cerebellum is important in implicit memory, and the amygdala
is important in emotional memory. A number of neurotransmitters are important in consolidation
and memory. Evidence for the role of different brain structures in different types of memories
comes in part from case studies of patients who suffer from amnesia.
Cognitive biases are errors in memory or judgment that are caused by the inappropriate use of
cognitive processes. These biases are caused by the overuse of schemas, the reliance on salient
and cognitive accessible information, and the use of rule-of-thumb strategies known as
heuristics. These biases include errors in source monitoring, the confirmation bias, functional
fixedness, the misinformation effect, overconfidence, and counterfactual thinking. Understanding
the potential cognitive errors we frequently make can help us make better decisions and engage
in more appropriate behaviors.
