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Chapter 5

Short-Term and Working Memory

Some Questions to Consider

  • Why can we remember a telephone number long enough to place a call, but then we forget it almost immediately?
  • How is memory involved in processes such as doing a math problem?
  • Do we use the same memory system to remember things we have seen and things we have heard?

What Is Memory?

  • Memory: processes involved in retaining, retrieving, and using information about stimuli, images, events, ideas, and skills after the original information is no longer present
  • Active any time some past experience has an impact on how you think or behave now or in the future

Modal Model of Memory

  • Atkinson and Shiffrin (1968)
  • Three different types of memory:

Sensory Memory – Initial stage that holds all incoming information for seconds or fractions of a second

Short-term Memory – Holds five to seven items for about 15 to 20 seconds.

Long-term Memory – Can hold a large amount of information for years or even decades

Modal Model of Memory

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Modal Model of Memory

  • Control processes: active processes that can be controlled by the person
  • Rehearsal
  • Strategies used to make a stimulus more memorable
  • Strategies of attention that help you focus on specific stimuli
  • There are many strategies or control processes that we can use to improve our memory.

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Modal Model of Memory:
Sensory Memory

  • Sensory Memory: The retention, for brief periods of time, of the effects of sensory stimulation.
  • Information decays very quickly
  • Persistence of vision: retention of the perception of light
  • Sparkler’s trail of light
  • Frames in film

Modal Model of Memory:
Sensory Memory

  • Measuring the capacity and duration of sensory memory (Sperling, 1960)
  • Array of letters is flashed quickly on a screen
  • Participants are asked to report as many as possible

Modal Model of Memory:
Sensory Memory

  • For the whole report method, participants were asked to report as many as could be remembered
  • They averaged 4.5 out of 12 letters (37.5%)

Modal Model of Memory:
Sensory Memory

  • For the partial report method: participants heard tone that told them which row of letters to report
  • Average of 3.3 out of 4 letters (82%)

Modal Model of Memory:
Sensory Memory

  • In the delayed partial report method: presentation of tone delayed for a fraction of a second after the letters were extinguished
  • Performance decreases rapidly

Modal Model of Memory:
Sensory Memory

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Modal Model of Memory:
Sensory Memory

  • Iconic memory: Brief sensory memory of the things that we see
  • Responsible for persistence of vision
  • Echoic memory: Brief sensory memory of the things that we hear
  • Responsible for persistence of sound

Modal Model of Memory:
Short-Term Memory

  • Short-term memory
  • Stores small amounts of information for a brief duration
  • Includes both new information received from the sensory stores and information recalled from long-term memory

Modal Model of Memory:
Short-Term Memory

  • Measuring the duration of short-term memory
  • Read three letters, then a number
  • T, W, N, 12
  • Begin counting backwards by threes
  • 12, 9, 6, 3, 0, etc.
  • After a set time, recall three letters

Modal Model of Memory:
Short-Term Memory

  • After three seconds of counting, participants performed at 80%
  • After 18 seconds of counting, participants performed at 10%
  • This reduction in performance is explained by the existence of decay
  • the vanishing of a memory trace due to the passage of time and exposure to competing stimuli
  • Short-term memory, when rehearsal is prevented, is about 15-20 seconds

Modal Model of Memory:
Short-Term Memory

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Modal Model of Memory:
Short-Term Memory

  • Proactive interference: occurs when information learned previously interferes with learning new information
  • Example: Your native language may make it more difficult to learn and remember a new foreign language
  • Retroactive interference: occurs when new learning interferes with remembering old learning
  • Example: After you get a new telephone number and use it for a while, you may have difficulty remembering your old phone number

Modal Model of Memory:
Short-Term Memory

  • Capacity of short-term memory
  • Digit span: how many digits a person can remember
  • Typical result: 5-8 items
  • Most textbooks say the “magic” number is 7, which is why phone numbers were always 7 digits before we had to add the area code
  • But what is an item?

Modal Model of Memory:
Short-Term Memory

  • Change detection
  • Participants are shown a picture, followed by a blank screen and then a new picture and asked if the original picture had changed.

  • The more items there are, the harder it is for people to detect the change.
  • This study shows that performance declines after more than 4 boxes are shown.

Modal Model of Memory:
Short-Term Memory

  • In other versions, more practical, real-life images are shown.
  • As number of items in the picture increases past 4, the accuracy decreases.

Modal Model of Memory:
Short-Term Memory

  • Chunking
  • small units can be combined into larger meaningful units increasing the amount of information that can be held in short-term memory by grouping related items together
  • Phone numbers are separated by the dash, creating chunks of 3-4 numbers that make it easier to remember;

249-619-1958

Placing the dash in the right place or arranging the letters in a more meaningful way can really help!

FB – ICI – A – NB – CIRS = FBI CIA NBC IRS

Modal Model of Memory:
Short-Term Memory

  • Ericsson et al. (1980)
  • Trained a college student with average memory ability to use chunking
  • S.F. had an initial digit span of 7
  • After 230 one-hour training sessions, S.F. could remember up to 79 digits by chunking them into meaningful units

Modal Model of Memory:
Short-Term Memory

  • Alvarez and Cavanaugh (2004)
  • Used colored squares as well as complex objects
  • Used the change detection procedure

Modal Model of Memory: Short-Term Memory

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Working Memory

  • Similar concept to short-term memory
  • Baddeley and Hitch (1974)
  • Working memory
  • Limited capacity system for temporary storage and manipulation of information for complex tasks such as comprehension, learning, and reasoning

Working Memory

  • Working memory differs from STM
  • STM holds information for a brief period of time
  • WM is concerned with the processing and manipulation of information that occurs during complex cognition

Working Memory

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Phonological Loop

  • https:// www.youtube.com/watch?v=DxHXJmGH8i8
  • Phonological similarity effect
  • When letters or words sound similar to each other they are often confused (hatch, latch)
  • Word-length effect
  • Memory for lists of words is better for short words than for long words
  • Takes longer to rehearse long words and to produce them during recall

Phonological Loop

  • Articulatory suppression
  • Results when a participant is asked to make an irrelevant sound (the, the, the) while trying to remember something.
  • Prevents one from rehearsing items to be remembered
  • Reduces memory span
  • Eliminates word-length effect
  • Reduces phonological similarity effect for reading words

Visuospatial Sketch Pad

  • Visual imagery
  • The creation of visual images in the mind in the absence of a physical visual stimulus
  • Mental rotation task (Shepard & Metzler, 1971)

  • Tasks that called for greater rotations took longer

Working Memory

  • Working Memory is set up to process different types of information simultaneously
  • Working memory has trouble when similar types of information are presented at the same time

Working Memory

The Central Executive

  • Attention controller
  • Focus, divide, switch attention
  • Controls suppression of irrelevant information
  • Has been studied extensively in patients with frontal lobe damage.
  • These patients have a defect called perseveration.
  • Perseveration
  • Refers to repeatedly performing the same action or thought even if it is not achieving the desired goal
  • Participant learns a rule, then the researcher switches the rule and the patient continues with the old rule.
  • https://www.youtube.com/watch?v=-vwA9QmJRy8

WM and the Brain:
Individual Differences

  • As with every behavior or function, not everyone is the same. There are individual differences between people whereby some people have a low capacity for working memory and others have a high capacity for working memory.
  • Vogel et al. (2005)
  • Determined participants’ Working Memory and found that people could be separated into two groups.
  • High-capacity WM group
  • Low-capacity WM group
  • Shown either simple or complex stimuli
  • Measured ERP responses - the measured brain response that is the direct result of a specific sensory, cognitive, or motor event.

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WM and the Brain:
Individual Differences

Episodic Buffer

  • Backup store that communicates with long-term memory and working memory components
  • Holds information longer and has greater capacity than either the phonological loop or visuospatial sketch pad

Episodic Buffer

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Working Memory and the Brain

Working Memory and the Brain

  • Funahashi et al. (1989)
  • Single cell recordings from monkey’s prefrontal cortex during a delay-response task

Working Memory and the Brain

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Working Memory and the Brain