short-term memory kimberley clow kclow2@uwo.ca

Short-Term Memory

Kimberley Clow

kclow2@uwo.ca

http://instruct.uwo.ca/psychology/130/

Outline

What is Memory?StructureSTM vs. LTM

Capacity of STM

ForgettingDecay vs. Interference

Structure of STM

What Is Memory?

Two different types of memoryShort-Term MemoryLong-Term Memory

Important TermsStructureEncodingRetrievalForgetting

What is the Structure?

Atkinson & Shiffrin Modal Model or Multi-Store ModelModal Model or Multi-Store Model

What Words?1. drum2. curtain3. bell4. coffee5. school6. parent7. moon8. garden9. hat10. farmer11. nose12. turkey13. colour14. house15. river

quite good recall

bad recall

best recall

Serial Position CurveSerial Position Curve%

rec

alle

d

position of word in list

5th 10th 15th

100 Primacy Effect (quite good recall)

Recency Effect (best recall)

Asymptote (bad recall)

Primacy & Recency

IQ

Word frequency

Delay

Distraction

Low frequency

Low IQ

distracter task

10 sec delay

Neurological Evidence

CWProblems with short-term memory

Anterograde amnesia

HMShort-term memory was goodProblems with long-term memory

KFShort-term memory impaired

Span of apprehension was 1 item

Short-Term Memory

What is Short-Term Memory?The information that is in consciousness

right nowThe limited-capacity memory

component for temporary information storage and manipulation

The mental workplace for retrieval and use of already known information

The Magical Number 7 (± 2)

“My problem is that I have been persecuted by an integer. For seven years this number has followed me around, has intruded in my most private data, and has assaulted me from the pages of our most public journals.

This number assumes a variety of disguises, being sometimes a little larger and sometimes a little smaller than usual, but never changing so much as to be unrecognizable…

Either there really is something unusual about the number or else I am suffering from delusions of persecution.”

Capacity of STM

How can we function on such a small short-term memory capacity?

Techniques that aid memoryRehearsal

Eases transfer to LTMMnemonic Devices

Strategies for increasing STM capacity

Chunking

IFYOUGROUPTOGETHERYOUREMEMBERBETTER

Which is Easier?

CHJ MLK ODW

Which is Easier?

FBI PHD IBM

Which is Easier?

AFGHANISTANVENEZUELANICARAGUA

Which is Easier?

CUBA

MALTA

GREECE

Individual Differences

Mnemonic Differences Novice vs. Expert

What About Forgetting?

The Brown-Peterson Task

Forget the letters very quickly

70% accuracy after 3 s 10% accuracy after 15 s

Concluded that items decay out of short term memory very quickly

Decay vs. Interference

Two reasons why we may forget things Decay

Information fades from memory

Not influenced by other information

Interference Other information disrupts

learning Proactive Interference Retroactive Interference

Probe Digit Task

Release From PI

Probe Digit Task Results due to # of items,

not time Interference NOT decay

Brown-Peterson results probably due to proactive interference of past trials

Is there a way to eliminate proactive interference?

Searching STM

Sternberg Shown a string of characters (1-6)

53427

Then a single character appears (probe) 7

Was the probe in the string? Measure speed of response depending upon…

How many characters were presented The sequential position of the probed character Whether the answer was yes or no

3 Possible Search Patterns

What Info Is in Memory?

VerbalConfuse E with D (auditory information)

Not E with F (visual information)

SemanticRelease from proactive interference (PI)

Changing categories is semantic info

VisualMental rotation tasks

Mental Rotation Task

Which of the three objects below matches the standard?

Baddeley’s Working-Memory

Evidence

Remember a string of 6 numbers or letters

Simultaneously do a reasoning taskShown stimuli like “AB”Then asked a true or false question

A precedes B B precedes AB is preceded by A A is preceded by BB does not precede A A does not precede BA is not preceded by B B is not preceded by A

Evidence

Test for limited resources & visual memory Verbal task or

spatial task Verbal response or

spatial response

Yes Yes

NoNo

No

NoNo

YesYes

Visual response competes with resources of visuo-spatial sketchpad

Summary

Short-term memory is limited in capacity Decay vs. Interference

Short-term memory is where information is consciously manipulated Rehearse to maintain information temporarily or to

transfer to long-term memory Workbench for manipulating current conscious

information

Short-term memory specializes in verbal and visuo-spatial information