Short-Term Memory

1. Short-Term Memory Kimberley Clow kclow2@uwo.ca http://instruct.uwo.ca/psychology/130/

2. Outline • What is Memory? • Structure • STM vs. LTM • Capacity of STM • Forgetting • Decay vs. Interference • Structure of STM

3. What Is Memory? • Two different types of memory • Short-Term Memory • Long-Term Memory • Important Terms • Structure • Encoding • Retrieval • Forgetting

4. What is the Structure? • Atkinson & Shiffrin • Modal Model or Multi-Store Model

5. drum • 2. curtain • 3. bell • 4. coffee • 5. school • 6. parent • 7. moon • 8. garden • 9. hat • 10. farmer • 11. nose • 12. turkey • 13. colour • 14. house • 15. river quite good recall bad recall best recall What Words?

6. 5th 10th 15th position of word in list Serial Position Curve Primacy Effect(quite good recall) Recency Effect(best recall) 100 Asymptote(bad recall) % recalled

7. distractertask 10 sec delay Lowfrequency Low IQ Primacy & Recency Word frequency Distraction IQ Delay

8. Neurological Evidence • CW • Problems with short-term memory • Anterograde amnesia • HM • Short-term memory was good • Problems with long-term memory • KF • Short-term memory impaired • Span of apprehension was 1 item

9. Short-Term Memory • What is Short-Term Memory? • The information that is in consciousness right now • The limited-capacity memory component for temporary information storage and manipulation • The mental workplace for retrieval and use of already known information

10. 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.”

11. Capacity of STM • How can we function on such a small short-term memory capacity? • Techniques that aid memory • Rehearsal • Eases transfer to LTM • Mnemonic Devices • Strategies for increasing STM capacity

12. Chunking IFYOUGROUPTOGETHERYOUREMEMBERBETTER

13. Which is Easier? CHJ MLK ODW

14. Which is Easier? FBI PHD IBM

15. Which is Easier? AFGHANISTAN • VENEZUELA • NICARAGUA

16. Which is Easier? CUBA MALTA GREECE

17. Individual Differences • Mnemonic Differences • Novice vs. Expert

18. What About Forgetting?

19. 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

20. 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

21. Probe Digit Task

22. 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?

23. 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

24. 3 Possible Search Patterns

28. Verbal Confuse E with D (auditory information) Not E with F (visual information) Semantic Release from proactive interference (PI) Changing categories is semantic info Visual Mental rotation tasks What Info Is in Memory?

29. Mental Rotation Task • Which of the three objects below matches the standard?

30. Baddeley’s Working-Memory

31. Evidence • Remember a string of 6 numbers or letters • Simultaneously do a reasoning task • Shown stimuli like “AB” • Then asked a true or false question • A precedes B B precedes A • B is preceded by A A is preceded by B • B does not precede A A does not precede B • A is not preceded by B B is not preceded by A

33. Yes Yes No No No No No Yes Yes Evidence • Test for limited resources & visual memory • Verbal task or spatial task • Verbal response or spatial response

34. Visual response competes with resources of visuo-spatial sketchpad

35. 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