discussions

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Memory

Chapter 8

EXPLORING PSYCHOLOGY DAVID G. MYERS | C. NATHAN DEWALL

Chapter Overview

• Studying and Encoding Memories

• Storing and Retrieving Memories

• Forgetting, Memory Construction, and Improving Memory

Studying and Encoding Memories

• Memory • Persistence of learning over time through the

encoding, storage, and retrieval of information

• Evidence of memory • Recalling information

• Recognizing it

• Relearning it more easily on a later attempt

Measuring Retention

• Three measures of memory retention: • Recall: A measure of memory in which the person

must retrieve information learned earlier, as on a fill- in-the-blank test.

• Recognition: A measure of memory in which the person identifies items previously learned, as on a multiple-choice test.

• Relearning: A measure of memory that assesses the amount of time saved when learning material again.

Ebbinghaus’ Retention Curve

• Ebbinghaus found that the more times he practiced a list of nonsense syllables on day 1, the less time he required to relearn it on day 2. Speed of relearning is one measure of memory retention (Baddeley, 1982).

• Tests of recognition and of time spent relearning demonstrate that we remember more than we can recall.

Memory Models (part 1)

• Psychologists use memory models to think and communicate about memory. • Information-processing model

• Compares human memory to computer operations

• Involves three processes: encoding, storage, and retrieval

• Connectionism information-processing model • Focuses on multitrack, parallel processing—the processing

of many aspects of a problem simultaneously

• Views memories as products of interconnected neural networks

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Memory Models (part 2)

• Three processing stages in the classic Atkinson-Shiffrin (1968) model: 1. We record to-be-remembered information as a

fleeting sensory memory, the immediate, very brief recording of sensory information.

2. We then process information into short-term memory (activated memory that holds a few items briefly), where we encode it through rehearsal.

3. Finally, information moves into long-term memory, the relatively permanent and limitless storehouse of the memory system of knowledge, skills, and experiences, for later retrieval.

A Modified Three-Stage Processing Model of Memory

Memory Models (part 3)

• Working memory • Stresses the active processing occurring in the

second memory stage

• Is a newer understanding of short-term memory that adds conscious, active processing of incoming auditory and visual-spatial information, and of information retrieved from long-term memory

• In Baddeley’s (2002) model, this focused processing is handled by a central executive.

Encoding Memories

• Dual-Track Memory: Effortful Versus Automatic Processing • Explicit memory (declarative memory): Memory of

facts and experiences that one can consciously know and “declare.” We encode explicit memories through conscious effortful processing.

• Implicit memory (nondeclarative memory): Retention of learned skills or classically conditioned associations independent of conscious recollection. We encode implicit memories through automatic processing, without our awareness.

Automatic Processing and Implicit Memories (part 1)

• Implicit memories include procedural memory for automatic skills and classically conditioned associations among stimuli

• Information is automatically processed about: • Space

• Time

• Frequency

Automatic Processing and Implicit Memories (part 2)

• Automatic processing happens effortlessly.

• With experience and practice, learned skills such as reading and driving become automatic.

• Many skills are developed this way.

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Effortful Processing and Explicit Memories

• Sensory memory • Sensory memory feeds

our active working memory, recording momentary images of scenes or echoes of sounds.

• Two types of sensory memory are iconic memory and echoic memory.

Sensory Memory

• Sensory memory: First stage in forming explicit memories

• Iconic memory: Picture-image memory of visual stimuli lasting no more than a few tenths of a second

• Echoic memory: Sound memory of auditory stimuli; can be recalled within 3 or 4 seconds

Short-Term Memory Capacity

• Short-term memory holds a few items briefly (such as the seven digits of a phone number while dialing) before the information is stored or forgotten.

• George Miller (1956) proposed the magical number 7: People can store about seven bits of information (give or take two).

• Baddeley and colleagues (1975) have confirmed that without distraction, we can recall about seven digits or about six letters or five words.

• Capacity varies by age and distractions at the time of memory tasks.

Effortful Processing Strategies

• Chunking: Organization of items into familiar, manageable units; often occurs automatically.

• Mnemonics: Memory aids, especially techniques that use vivid imagery and organizational devices. • The peg-word system harnesses our superior visual-

imagery skill.

• Hierarchies: Organization of items into a few broad categories that are divided and subdivided into narrower concepts and facts.

Distributed Practice

• Spacing effect: Encoding is more effective when it is spread over time. • Distributed practice produces better long-term retention than is

achieved through massed study or practice. • Massed practice produces speedy short-term learning and

feelings of confidence, but leads to quick forgetting. • Testing effect:

• Enhanced memory after retrieving, rather than simply rereading, information.

• Repeated self-testing (using the Retrieve It and Testing Effect questions in this text, for example) does more than assess learning: It improves it.

• Practice may not make perfect, but smart practice— occasional rehearsal with self-testing—makes for lasting memories.

Levels of Processing

• Verbal information is processed at different levels, which affects long-term retention. • Shallow processing encodes on a very basic level

(a word’s letters) or on a more intermediate level (a word’s sound).

• Deep processing encodes semantically, based on word meaning.

• The deeper (more meaningful) the processing, the better our retention.

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Making Material Personally Meaningful

• New information is processed easily when it is meaningful or related to our experience.

• Ebbinghaus estimated that learning meaningful material requires one-tenth of the effort compared with learning nonsense material.

• We have especially good recall for information we can relate to ourselves—a tendency referred to as the self-reference effect.

• The amount of information remembered depends both on the time spent in learning it and on your making it meaningful for deep processing.

Memory Storage

• Our capacity for storing long-term memories is essentially limitless.

• This is contrary to the belief that we can add more items only if we discard old ones.

Retaining Information in the Brain (part 1)

• Despite the brain’s vast storage capacity, we do not store information as libraries store their books, in single, precise locations.

• Instead, brain networks encode, store, and retrieve the information that forms our complex memories. That is, the brain distributes the components of a memory across a network of locations in the brain.

• Some of the brain cells that fired when we experienced something fire again when we recall it.

Retaining Information in the Brain (part 2)

• We have two conscious memory systems: • Semantic memory: Explicit memory of facts and general

knowledge

• Episodic memory: Explicit memory of personally experienced events.

• Hippocampus: A neural center located in the limbic system, which registers and temporarily holds elements of explicit memories before moving them to other brain regions for long-term storage

• Memory consolidation: Neural storage of long- term memories

Explicit-Memory System: The Hippocampus

• Explicit memories for facts and episodes are processed in the hippocampus (orange structures) and fed to other brain regions for storage.

Implicit Memory System: Cerebellum and Basal Ganglia

• The cerebellum plays an important role in forming and storing implicit memories created by classical conditioning.

• The basal ganglia—deep brain structures involved in motor movement—facilitate formation of our procedural memories for skills.

• Infantile amnesia • Conscious memory of the first three years is blank. • Command of language and a well-developed

hippocampus is needed for such memory. • The hippocampus is one of the last brain structures to

mature.

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The Amygdala, Emotions, and Memory

• Excitement or stress triggers hormone production and provokes the amygdala (two emotion- processing clusters in the limbic system) to engage memory.

• Emotions often persist with or without conscious awareness.

• Emotional arousal causes an outpouring of stress hormones; the hormones lead to activity in the brain’s memory-forming areas.

• Flashbulb memories—clear memories of emotionally significant moments or events—occur via emotion-triggered hormonal changes and rehearsal.

Key Memory Structures in the Brain

Synaptic Changes

• Long-term potentiation (LTP) • Increase in a synapse’s firing potential after brief, rapid

stimulation

• After LTP, the brain will not erase memories

• Believed to be a neural basis for learning and memory

• Kandel and Schwartz (1982): • Observed synaptic changes during learning in the

neurons of the California sea slug, Aplysia.

• Pinpointed changes in sea slugs’ neural connections: With learning, more serotonin is released and cell efficiency is increased.

Aplysia

• Aplysia, the California sea slug, which neuroscientist Eric Kandel studied for 45 years, has increased our understanding of the neural basis of learning and memory.

Doubled Receptor Sites Our Two Memory Systems

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Memory Retrieval: Retrieval Cues

• Memories are held in storage by a web of associations.

• Retrieval cues serve as anchor points for pathways to memory suspended in this web.

• When you encode into memory the name of the person sitting next to you in class, you associate it with other bits of information about your surroundings, mood, seating position, and so on.

• The best retrieval cues come from associations formed at the time a memory is encoded.

• Priming: Activation, often unconsciously, of particular associations in memory.

Retrieval Cues (part 1)

Priming • After seeing or

hearing rabbit, we are later more likely to spell the spoken word hair/hare as h-a-r-e (Bower, 1986).

• Associations unconsciously activate related associations.

Retrieval Cues (part 2)

• Context-dependent memory • Recall of specific information improves when the

contexts present at encoding and retrieval are the same.

• Cues and contexts specific to a particular memory will be most effective in helping recall.

Retrieval Cues (part 3)

• State-dependent memory • Emotions that accompany good or bad events

become retrieval cues.

• Mood-congruent memory: The tendency to recall experiences that are consistent with one’s current good or bad mood.

• Passions are exaggerated: • In a bad mood, we may read someone’s look as a glare and

feel even worse.

• In a good mood, we may encode the same look as interest and feel even better.

The Serial Position Effect Why Do We Forget?

• William James (1890): “If we remembered everything, we should on most occasions be as ill off as if we remembered nothing.”

• It’s surely a blessing that most of us discard the clutter of useless or out-of-date information—but our sometimes unpredictable memory can be frustrating.

• Anterograde amnesia: Inability to form new memories.

• Retrograde amnesia: Inability to retrieve information from one’s past.

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When Do We Forget?

• Forgetting can occur at any memory stage.

• When we process information, we filter, alter, or lose most of it.

Encoding Failure

• Much of what we sense, we never notice.

• What we fail to encode, we will never remember. • Age: Encoding lag is linked to age-related memory

decline.

• Attention: Failure to notice or encode contributes to memory failure,

Forgetting as Encoding Failure Storage Decay

• Even after encoding something well, we sometimes later forget it.

• The course of forgetting is initially rapid, but then levels off with time.

• Physical changes in the brain occur as memory forms (memory trace).

Ebbinghaus’ Forgetting Curve Retrieval Failure (part 1)

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Retroactive Interference Retrieval Failure (part 2)

• Interference • Proactive (forward-acting) interference: Prior learning

disrupts recall of new information. • Retroactive (backward-acting) interference: New learning

disrupts recall of older information. • Motivated forgetting

• Sigmund Freud argued that we repress painful or unacceptable memories to protect our self-concept and to minimize anxiety.

• Today’s researchers think repression rarely, if ever, occurs.

• Forgetting is more likely when information is neutral, not emotional; we often have intrusive memories of the very same traumatic experiences we would most like to forget.

Memory Construction Errors (part 1)

• Memory is not precise. We don’t just retrieve memories, we reweave them.

• Elizabeth Loftus and Katherine Ketcham (1994): “Our memories are flexible and superimposable, a panoramic blackboard with an endless supply of chalk and erasers.”

• Reconsolidation: A process in which previously stored memories, when retrieved, are potentially altered before being stored again.

Misinformation and Imagination Effects

• Misinformation effect: Corruption of a memory by misleading information.

• Even repeatedly imagining fake actions and events can create false memories.

• Digitally altered photos can produce imagination inflation—that is, memories of events that people have not actually experienced.

Memory Construction Memory Construction Errors (part 2)

• Source amnesia (source misattribution): Attributing to the wrong source an event we have experienced, heard about, read about, or imagined.

• Source misattribution, along with the misinformation effect, is at the heart of many false memories.

• Déjà vu: That eerie sense that “I’ve experienced this before.” Cues from the current situation may unconsciously trigger retrieval of an earlier experience.

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Discerning True and False Memories

• False memories feel like real memories and can be persistent, but are usually limited to the gist of the event.

• False memories are often a result of faulty eyewitness testimony.

• Memory construction helps explain: • Why dating partners who have fallen in love overestimate

their first impressions of each other. • Why people asked how they felt 10 years ago about

certain social issues recall attitudes closer to their current views than to the views they actually reported a decade earlier.

Children’s Eyewitness Recall

• Studies by Ceci and Bruck (1993, 1995): • The effect of suggestive interviewing techniques. • How easily children’s memories can be molded: In

one study, 58 percent of preschoolers produced false stories about one or more unexperienced events.

• Children can often accurately recall events when nonleading questions are asked by a neutral person, in words the children can understand, and the questions are asked soon after the event (ideally before children have talked much to involved adults).

Can Memories of Childhood Sexual Abuse Be Repressed and Then Recovered? (part 1)

• The debate between memory researchers and some well-meaning therapists focuses on whether most memories of early childhood abuse are repressed and can be recovered during therapy using “memory work” techniques that may involve “guided imagery,” leading questions, hypnosis, or dream analysis.

• Two tragedies of child abuse: • When people don’t believe abuse survivors • When innocent people are falsely accused

• There’s a need to find a sensible common ground.

Can Memories of Childhood Sexual Abuse Be Repressed and Then Recovered? (part 2)

• Those committed to protecting abused children and those committed to protecting wrongly accused adults have agreed on the following points: • Sexual abuse happens. • Injustice happens. • Forgetting happens. • Recovered memories are commonplace, but this doesn’t

necessarily mean the unconscious mind repressed them. • Memories of things happening before age 3 are

unreliable. • Memories “recovered” under hypnosis or the influence of

drugs are especially unreliable. • Memories, whether real or false, can be emotionally

upsetting.

Improving Memory

• The SQ3R (Survey, Question, Read, Retrieve, Review) study technique used in this book incorporates several learning strategies: • Rehearse repeatedly. • Make the material meaningful. • Activate retrieval cues. • Use mnemonic devices. • Minimize interference. • Sleep more. • Test your own knowledge, both to rehearse it and to

find out what you do not yet know.