Forgetting and Interference in Short-term memory Brown-Peterson Task

1. Forgetting and Interference in Short-term memory   Brown-Peterson Task Proactive Interference (PI) Release from PI Retrieval of info from STM Sternberg (1966) Task Stages Findings

2. Forgetting and Interference in Short-term memory Brown (1959) Peterson and Peterson (1959) both tested a decay theory of immediate memory considered possibility of proactive interference Task (Brown-Peterson task)

3. Brown-Peterson task get 3 letters to remember get a number (start counting backward by 3s) recall letters when given a cue

5. + + +

6. X S V

7. 3 6 1

8. *****

10. + + +

11. D L F

12. 2 9 2

13. *****

14. Proportion of Items Recalled as a Function of (Filled) Retention Interval 1.0 P(r) 0.0 0 3 6 9 12 15 18 Retention Interval (s)

15. Proportion of Items Recalled as a Function of (Filled) Retention Interval 1.0 P(r) 0.0 0 3 6 9 12 15 18 Retention Interval (s)

16. Proportion of Items Recalled as a Function of (Filled) Retention Interval 1.0 Decay or Proactive Interference? P(r) 0.0 0 3 6 9 12 15 18 Retention Interval (s)

17. Considered Proactive Interference Looked at performance for 4 blocks of trials If PI occurred, then performance should get worse across the 4 blocks of trials

18. Considered Proactive Interference Looked at performance for 4 blocks of trials If PI occurred, then performance should get worse across the 4 blocks of trials Mean % Accuracy by Block Block 1 2 3 4 33 41 40 43

19. Considered Proactive Interference Looked at performance for 4 blocks of trials If PI occurred, then performance should get worse across the 4 blocks of trials Mean % Accuracy by Block Block 1 2 3 4 33 41 40 43 No evidence of PI; so, seems like evidence for decay (also thought retroactive interference was eliminated)

20. Peterson and Peterson (1959) used 2 practice trials then looked at mean performance for blocks of 12 trials Keppel and Underwood (1968) Maybe PI builds up quickly examined performance over first few trials If PI occurs, then performance should get worse across trials (the more trials, the more PI)

21. Proportion of Items Recalled by Trial Number And Recall Delay 1.0 3-s delay P(r) 18-s delay 0.0 1 2 3 4 5 6 Trial Number

22. Keppel and Underwood (1968) Maybe PI builds up quickly examined performance over first few trials If PI occurs, then performance should get worse across trials (the more trials, the more PI) Conclusion: PI occurs, builds up quickly

23. Proportion of Items Recalled by Trial Number And Recall Delay 1.0 3-s delay P(r) 18-s delay 0.0 1 2 3 4 5 6 Trial Number

24. Keppel and Underwood (1968) Maybe PI builds up quickly examined performance over first few trials If PI occurs, then performance should get worse across trials (the more trials, the more PI) Conclusion: PI occurs, builds up quickly Also, little forgetting without PI (evidence against decay theory)

25. Keppel and Underwood (1968) Maybe PI builds up quickly examined performance over first few trials If PI occurs, then performance should get worse across trials (the more trials, the more PI) Conclusion: PI occurs, builds up quickly Also, little forgetting without PI (evidence against decay theory) Note: distractor task is producing retroactive interference, too

26. Wickens (1968) obtained quick build-up of PI with different category exemplars (e.g., examples of professions, fruits, etc.) Manipulation – category switch continued with same category (no switch) vs. changed to a new category (switch)

27. Proportion of Items Recalled by Trial Number And Recall Delay 1.0 fruit (switch) professions P(r) fruits fruit (no switch) 0.0 1 2 3 4 5 6 Trial Number

28. Wickens (1968) obtained quick build-up of PI with different category exemplars (e.g., examples of professions, fruits, etc.) Manipulation – category switch continued with same category (no switch) vs. changed to a new category (switch) Release from PI due to a shift in material Conclusion: Build-up of PI due to similar material (interference from similar material)

29. Forgetting and Interference in Short-term memory   Brown-Peterson Task Proactive Interference (PI) Release from PI Retrieval of info from STM Sternberg (1966) Task Stages Findings

30. Retrieval of info from STM Sternberg’s (1966) task first, get a set of letters to remember (B K V J) called the memory set (the memory set size can vary)

31. Retrieval of info from STM Sternberg’s (1966) task first, get a set of letters to remember (B K V J) called the memory set (the memory set size can vary) then get a probe (a letter): encode the probe

32. Retrieval of info from STM Sternberg’s (1966) task first, get a set of letters to remember (B K V J) called the memory set (the memory set size can vary) then get a probe (a letter): encode the probe scan items in STM

33. Retrieval of info from STM Sternberg’s (1966) task first, get a set of letters to remember (B K V J) called the memory set (the memory set size can vary) then get a probe (a letter): encode the probe scan items in STM make decision: Is the probe a letter in the memory set ?

34. Retrieval of info from STM Sternberg’s (1966) task first, get a set of letters to remember (B K V J) called the memory set (the memory set size can vary) then get a probe (a letter): encode the probe scan items in STM make decision: Is the probe a letter in the memory set ? press button for yes (a positive response) or button for no (a negative response)

35. Retrieval of info from STM Sternberg’s (1966) task first, get a set of letters to remember (B K V J) called the memory set (the memory set size can vary) then get a probe (a letter): encode the probe scan items in STM make decision: Is the probe a letter in the memory set ? press button for yes (a positive response) or button for no (a negative response) Collect reaction time (RT) for response

36. B V

37. V

39. R C

40. T

42. B V M S

43. S

45. R C G W

46. T

47. Scan: Compare probe to items in memory set Encode probe Execute motor response Decision yes/no

49. Scan: Compare probe to items in memory set Encode probe Execute motor response Decision yes/no How do we scan items in STM?

50. Scan: Compare probe to items in memory set Encode probe Execute motor response Decision yes/no How do we scan items in STM? all at the same time (parallel search)? one at a time (serial search)?