5. Short-term memory

Memory ovreview

Sensory Stores

• Visual Sensory Memory/Iconic Memory

• Auditory Sensory Memory/Echoic Memory

Short-Term Memory

• Holds information for up to 30 seconds

• Limited in Capacity

Long-Term Memory

• Holds information for long periods of time

• Unlimited capacity

Short-term memory

_________________ - The capacity to hold a small amount of information in mind in an active, readily available state for a short period of time

• STM often refers to the input and storage of new information

  • embodies the notion of a limited-capacity system

Aspects of STM

STM

_______________ - Three types:

• Where the immediately present moment is held in consciousness

• Where active mental effort is expended

• Where comprehension takes place

Synonyms for STM

STM

_______________ - lots of definitions:

• Working memory

• Short-term store

• Primary Memory

• Elementary memory; intermediate memory; temporary memory

STM vs. Working Memory

_______________

STM

• Older

• Input and storage of new information

  • E.g., remembering a phone number

Working Memory

• Newer

• Processing and storage

• The mental workbench

  • E.g., Understanding a sentence

Bottleneck

STM

______________ - LOTS of info, but only some gets in

• STM cannot encode and hold vast amounts of new info

  • E.g., Recall as many of these letters as you can in the order in which they appeared

Miller’s Magical Number Seven, Plus or Minus Two

• Cowan, 2010: 3-5 Chunks

Chunking

STM - Bottleneck (overcoming it)

_____________ - grouping information into richer, more complex items or units called chunks

Recoding

STM - Bottleneck (overcoming it)

____________ - the process of grouping items together and then remembering the newly formed groups

Two conditions:

1. Time/Resources;

2. Well-learned

Mnemonic devices

STM - Bottleneck (overcoming it)

________________ - Any mental device or strategy that provides a useful rehearsal strategy for storing and remembering material

• E.g., Method of Loci

The Brown-Peterson Task

________________ - How long does non-rehearsed information stay in STM? — says basically, performance gets worse

On each trial, the subject sees three letters, followed by three numbers

• e.g., PIR-393.

• Subjects must remember the letters while counting backwards by 3s from the number.

  • Plot recall accuracy by time spent counting.

Decay

Brown-Peterson Task → Interpretation

______________ (or fading) - Loss of a memory trace due simply to the passage of time

Interference

Brown-Peterson Task → Interpretation

______________ - is the loss of a memory trace due to competition from other stimuli or events

Decay hypothesis

Brown-Peterson Task → Challenges → Waugh and Norman’s (1965) predictions

________________ - If forgetting was caused by decay, then the 16 second group (1 word/second) would have lower recall accuracy.

• i.e. 16 second group would forget more

Waugh and Norman

Brown-Peterson Task → Challenges

___________________ (1965) - Participants heard a list of 16 digits read at either 1 or 4 digits per second.

Last digit was a repeat of an earlier one. Participant had to remember which digit came after it.

• E.g., 7, 4, 6, 9…  4 → remember 6

Key: presentation time of the lists

Interference hypothesis

Brown-Peterson Task → Challenges → Waugh and Norman’s (1965) predictions

________________ - If forgetting was caused by interference the two groups should be similar.

Waugh and Norman RESULTS

Brown-Peterson Task → Challenges → Waugh and Norman (1965)

_____________ - demonstrated that forgetting in short-term memory is primarily due to interference from new information, rather than simply the passage of time. 

Proactive interference (PI)

________________ - when older material interferes forward in time with your recollection of the current stimulus

• Previously presented material interferes with new learning

• Previous ruins ongoing

Retroactive interference (RI)

______________ - newer material interferes backward in time with your recollection of older items

• Recent material interferes with older learning

• Recent effects that ruin old

• E.g., Learning material towards the end of a course can interfere with your ability to remember material from earlier in the course.

Release from PI

Brown-Peterson Task

______________ (RPI) - a phenomenon where recall improves when the semantic category of items to be remembered is changed

• Wickens (1972)

  • Dog, Cat, Mouse – 745

  • Rabbit, Horse, Tiger – 687

  • Zebra, Giraffe, Elephant – 496

  • Doctor, Lawyer, Baker – 891

Short-term memory retrieval

STM

_______________ - Bringing knowledge to the foreground of thinking

• Allows us to manipulate or report the information

• Types of Recall: Free recall and serial recall

Free recall

Short-term memory retrieval → Types of recall

__________________ - recall the items in any order

• Ex: Grocery list

Serial recall

Short-term memory retrieval → Types of recall

______________ - recall items in exact order in which they were presented

• Ex: Phone number

Primacy effects

Short-term memory retrieval → Types of recall → Serial position curve explanations

________________ - Better memory for items in the early positions of the list— Long-term memory effect

• First items in a list get the best and most rehearsal

Recency effects

Short-term memory retrieval → Types of recall → Serial position curve explanations

__________________- Better memory for items at the end positions of the list— Short-term memory effect

• Last items in the list are still in STM at the time of recall

Evidence for the Standard explanation

Short-term memory retrieval → Types of recall → Serial position curve explanations

________________ - Interference task wipes out the recency effect, but not the primacy effect

Rehearsal

______________ - Keeps information in STM— Refresh in the mind

• Increases the probability that information will be transferred to long-term memory

Models of STM and Working Memory

_______________ - How is memory conceptualized?

• How do researchers think it works?

Multi-Store Models and Unitary Models

Multi-store models

• Atkinson and Shiffrin

• Baddeley’s Working Memory Model

Unitary-Store Models

• -No STM/LTM distinction

Multi-store models

Models of STM and Working Memory

________________ - models of memory that have multiple components for how memory works

• E.g., Atkinson and Shiffrin Modal Model

Overview of working memory

Working memory

Central executive

Components of working memory

___________ - In charge of planning future actions, initiating retrieval and decision processes as necessary, and integrating information coming into the system

• Monitors and coordinates subsystems

  • I.e., Visuo-Spatial Sketch Pad and Phonological Loop

• Has its own pool of resources

  • For use preforming tasks (e.g., comprehension)

  • E.g., “I know that you are not unaware of my inability to speak German”

  • Can supply subsystems

1) Visuo-spatial sketchpad (VSSP)

Components of working memory

___________ - One of two subsystems in WM— A system specialized for visual and spatial information

Displays and manipulates information

• E.g., Is the doorknob for your bedroom door on the left or right side?

• May be used in spatial awareness

Mental rotation

Components of working memory → VSSP

___________ - Mentally turning, spinning or rotating objects in the VSSP of working memory

Boundary extension

Components of working memory → VSSP

_______________ - People tend to misremember more of a scene than was actually viewed, as if the boundaries of an image were extended further out

• Ex: Anticipates active movement in the environment– your mind knows there is MORE to a scene than just what is shown in a picture or movie

Representational momentum

Components of working memory → VSSP

_______________ - the phenomenon of misremembering the movement of an object further along its path of travel than where it actually was when it was last seen

2) Phonological loop

Components of working memory

_______________ - Second subsystem in WM —The speech- and sound-related component responsible for rehearsal of verbal information and phonological processing

• Recycles information for immediate recall

• Two components:

  • Phonological Store

  • Articulatory loop

Episodic buffer

Components of working memory

_______________ - The portion of working memory where information from different modalities and sources is bound together to form new episodic memories

Phonological store

Components of working memory → phonological loop

_______________ - ½ components of phonological loop— passive store; “inner ear”

Articulatory loop

Components of working memory → phonological loop

_______________ - 2/2 components of phonological loop— active refreshing of information in the phonological store; “inner voice”

Articulatory suppression effect

Components of working memory → phonological loop

____________ - the finding that people have poorer memory for a set of words if they are asked to say something while trying to remember the words

Phonological similarity effect

Components of working memory → phonological loop

____________ - The finding that memory is poorer when people need to remember a set of words that are phonologically similar, compared to a set of words that are phonologically dissimilar

Dual task method

Studying working memory

_________________ - Two tasks are done simultaneously.

Can they be done independently or do they interfere with one another?

• Brooks (1968) → provided evidence that mentally scanning an imagined object and scanning a real object involve similar spatial processes

Support for WM

_______________ - Supported by some neurological evidence:

WM backed by localization of function & systems in the brain

• E.g., Occipital and parietal lobes are activated with VSSP working memory tasks

• E.g., Temporal lobes and language areas are activated in phonological loop tasks

Dual Task Research: Indicates that VSSP and PL are distinct systems

• E.g., Brooks (1968)

Dissociation Evidence: Short-term store is compromised, but no major deficits in learning, memory, or comprehension

Problems w/ WM

________________ -

Central Executive: Vague concept; catch-all

• “Little person in the head”

Episodic Buffer: Vaguely specified, not in original model

Limited Description of Modalities:

• Only two are included; what about the others?

Dissociations: Further neurological evidence indicates that there are dissociations within the subsystems

Unitary-store models of memory

Models of STM and Working Memory

______________ - One store of memory— no short-term/long-term distinction

• One set of representations that comprise our knowledge store

  • I.e., short-term memory is long-term memory that has recently been activated beyond a threshold

  • Attentional focus can be directed to activated representations

• Rehearsal strengthens representations

• Reevaluation of dissociations

Locating WM

______________ - a term for the set of mental operations, not a specific place in the brain.

• Reflects the currently activated portion of LTM

We have a system called working memory, but its not that its located in one specific location but is all over the place

Digit span task

Measuring WM span

______________ - Participants are exposed to a set of digits they must repeat back

• If successful, they get a longer list, then another…

Operation span

Measuring WM span

_____________ - Different types of tasks for different “operations”

• More dynamic measures of WM

• Ex: Reading span task, arithmetic task

These tasks can be used to investigate individual differences— A bigger operation span is typically advantageous

• Correlates with other faculties

  • Reading comprehension

  • Standardized academic tests (SAT)

  • Attention

  • Reasoning abilities

  • General intelligence

…Not the whole story for cognition

Reading span task

Measuring WM span → operation span examples

______________ - Requires the participant to read while holding information in WM

Participant reads two sentences, and has to repeat the last word in each

• If successful, they get three sentences, then four…

• Example:

  • Based on his prior experience, he was hired for the vacant managerial position. (have to remember position)

  • He believes the cookies were stolen by a rogue child. (have to remember child)

Arithmetic task

Measuring WM span → operation span examples

______________ - People see equations and read them out loud, then indicate if the answer is correct and say the word

• They do the same for the next equation and then, at some point, must report all of the words

• Example:

  • (6x2) – 2 = 10? SPOT

  • (5x3) -2 = 12? TRAIL

  • (10/2) + 6 = 10? GAS