Overview of Memory

1. Overview of Memory • Atkinson-Shiffrin Model RETRIEVAL ATTENTION Sensory Memory Short-Term Memory Long-Term Memory Sensory Signals REHEARSAL

2. Sensory Memory Supplementary reading: Cognition (on reserve) Averbach and Sperling (course pack) Part 1

3. Capacity • Describe a simple experiment that could measure the capacity of “memory”

4. Capacity • Describe a simple experiment that could measure the capacity of “memory” • Briefly present some letters or digits and then ask the subject to report them • Called “whole report”

5. Capacity +

6. Capacity F S F E G S A U T O C G +

7. Capacity “Recall as many letters as you can”

8. Capacity • George Sperling - Systematic investigation of memory capacity • Result: subjects accurately recall about 4 items • What can you conclude from this result? • Maybe subjects can only hold about 4 items?

9. Capacity • Could it be that subjects had encoded all the lettersbut failed to retrieve the information?

10. Capacity • For example: What if they forgot the information before they could report it? • You would get the same result! • How could you modify the experiment to measure the instantaneous capacity, before any forgetting can occur?

11. Capacity • Partial Report - briefly present letters or digits and ask subject to report only some of them “Report the letters in the row indicated by the arrow”

12. Capacity +

13. Capacity U E S B O D W A I B V S +

14. Capacity +

15. Capacity Which Letters?

16. Capacity • Partial Report • Result: subjects can recall any 4 letters that are indicated by the arrow !

17. Capacity • Partial Report • Result: subjects can recall any 4 letters that are indicated by the arrow ! • What does this mean about the capacity of memory?

18. Capacity • There is some part of the perception system that stores huge amounts of information… • in fact, if only a single letter is probed, instantaneous capacity is seen to be unlimited

19. Duration • There is some part of the perception system that stores huge amounts of information… • But for how long? How would you design an experiment to measure the duration of this high-capacity memory system?

20. Duration • There is some part of the perception system that stores huge amounts of information… • But for how long? How would you design an experiment to measure the duration of this high-capacity memory system? • Vary the onset of the probe

21. Duration • Partial Report 10 # of letters potentially recalled 4 0 0 ms 500 ms never Probe Delay

22. Duration • Partial Report 10 # of letters potentially recalled 4 0 0 ms 500 ms never Delay Interpretation: Information dwells in a brief storage “buffer” duration of storage lasts about 1/2 of one second

23. Iconic Memory • a brief storage of “raw data” in the visual system

24. Echoic Memory • Auditory information is stored in a similar sensory “buffer” • Echoic memory seems to last for several seconds

25. Properties of Sensory Memory • Brief (iconic ~500ms; echoic ~2 seconds)

26. Properties of Sensory Memory • Brief (iconic ~500ms; echoic ~2 seconds) • Virtually unlimited capacity

27. Properties of Sensory Memory • Brief (iconic ~500ms; echoic ~2 seconds) • Virtually unlimited capacity • pre-attentive

28. Properties of Sensory Memory • Brief (iconic ~500ms; echoic ~2 seconds) • Virtually unlimited capacity • pre-attentive What happens if you attend to information in Sensory Memory?

29. Overview of Memory • Atkinson-Shiffrin Model RETRIEVAL ATTENTION Sensory Memory Short-Term Memory Long-Term Memory Sensory Signals REHEARSAL

30. Characteristics of STM • Limited Capacity • George Miller • Subject is given longer and longer lists of to-be-remembered items (words, characters, digits) • Result: Subjects are successful up to about 7 “items” • Miller used the term “chunk” to refer to items in memory… • But what is a “chunk”?

31. Capacity and Forgetting from STM • Limited Capacity • Recalling takes time !

32. Capacity and Forgetting From STM • Naveh-Benjamin & Ayers (1986) • Showed that apparent span of STM is reduced for items that take longer to say

33. Capacity and Forgetting From STM • Brown (1958) and Peterson & Peterson (1959) • Subjects given list of “trigrams” • Rehearsal prevented by counting backward by threes • Showed that duration of STM is on the scale of seconds 1.0 Proportion Correct .5 .1 3 6 9 12 15 18 Delay (seconds)

34. Capacity and Forgetting From STM • Rundus (1971) • Long lists of “to-be-remembered” items • Primacy Effect – participants more likely to recall first few items • Recency Effect – participants more likely to recall last few items 1.0 Probability of Recall .5 .1 2 6 10 14 18 24 Position in list

35. Capacity and Forgetting from STM • Why do we “forget” from STM? • Does the memory trace decay? • not likely because with very small lists (like 1 item) retention is high for long intervals

36. Capacity and Forgetting from STM • Why do we “forget” from STM? • Does the memory trace decay? • not likely because with very small lists (like 1 item) retention is high for long intervals • Instead, it seems that information “piles up” and begins to interfere

37. Capacity and Forgetting from STM • Interference in STM is complex and specific