Chapter 3 The Modal Model

1. Chapter 3The Modal Model DaeWon Kim

2. Contents • Primary Memory • Broadbent’s Model • Waugh and Norman’s Model • Atkinson and Shiffrin’s Dual-Store Model • The Serial Position Curve and the Modal Model • Problems with the Modal Model • Continual distractor paradigm • Ratio rule • Changing distractor effect • Summary of the Modal Model

3. 1. Primary Memory • Dividing memory into multiple stores • One store specialized for briefly holding information : primary memory, working memory, short-term memory and short-term store. • Computer mataphor of memory • The resultant of two-store conception of memory : Modal Model (termed by Murdock (1974))

4. 1. Primary Memory① Broadbent’s Model • Human processor as a series of systems through which information flows • S-system : a preattentive sensory store, the forerunner of iconic and echoic memory • P-system : the site of awareness, limited capacity store S-System P-System

5. 1. Primary Memory① Broadbent’s Model • Three assumptions of Broadbent’s view • Primary and secondary memory involve separate memory systems. • Primary memory has a limited capacity. • Because information fades quickly in primary memory, information is retained only when it is actively rehearsed.

6. 1. Primary Memory① Broadbent’s Model • “The Magical Number Seven, Plus or Minus Two” [George Miller (1956)] • Absolute identification experiment • Hear a set of nine tones that vary only in frequency • On each trial, one of these tones is played, then tries to identify it. • The subject is informed whether the response is correct and, if not, what the correct response should have been.

7. 1. Primary Memory① Broadbent’s Model

8. 1. Primary Memory① Broadbent’s Model • Generally speaking, once the number of items reaches about eight or nine, subjects become unable to perform the task without errors • When stimuli vary along more than one dimension, identification is much better. • Ex) 26 letters of the alphabet A a B b C c D d I i O o ….

9. 1. Primary Memory ② Waugh and Norman’s Model • Perceived information first enters primary memory, a limited capacity structure • Some information is lost by displacement, as newly arriving items “bump out” already existing items. • Other information might be rehearsed and thus remain in primary memory longer. • Rehearsal also caused the information to be transferred to secondary memory, which has no capacity limitation. • Recall can be based on information in primary memory, secondary memory, or both.

10. 1. Primary Memory ③ Atkinson and Shiffrin’s Dual-Store Model

11. 1. Primary Memory ③ Atkinson and Shiffrin’s Dual-Store Model • Assumed that transfer began and continued during the entire time an item was in STS. • Experiment [ Hebb (1966) ] • Presented a series of nine-item lists to 40 subjects. • The lists were made up of the digits 1-9, presented in random order, and the task was recall the items in order. • Most of the lists contained novel orderings, but one list was repeated every third trial.

12. 1. Primary Memory ③ Atkinson and Shiffrin’s Dual-Store Model

13. 2. The Serial Position Curve and the Modal Model • Many experiments that tested predictions of the modal model concerned the serial position function observable with free recall. • Murdock(1962) reported a free recall experiment in which he presented lists of items that varied in length. • Lists of 10, 15, and 20 items.

14. 2. The Serial Position Curve and the Modal Model

15. 2. The Serial Position Curve and the Modal Model • Recency effect : excellent recall of the last few items • Due to the dumping of items from STS • Primacy effect : batter recall of the first few items • Due to the extra rehearsal the first few items get, which copies them into LTS

16. 2. The Serial Position Curve and the Modal Model • A strong prediction of the model is that if recall is delayed, the primacy effect should remain unaltered but the recency effect should disappear. • To test this prediction, Glanzer and Cunitz(1966) presented 15-item lists to subjects. • In the control condition, subjects immediately recalled as many of the words as they could. • In the other two conditions, subjects engaged in a distractor activity (counting backward) for either 10 or 30 seconds before recalling the items.

17. 2. The Serial Position Curve and the Modal Model

18. 2. The Serial Position Curve and the Modal Model • The modal model accounts for the following results • The serial position curve is seen regardless of list length.(Fig. 3.8) • The first items recalled will be the last few list items, followed by the first few list items. • Items will be rehearsed less and less as the serial position increases. • The recency effect, but not the primacy effect, is abolished if recall is delayed. (Fig. 3.10)

19. 3. Problems with the Modal Model • Continual distractor paradigm • An experiement reported by Watkins, Neath, and Sechler (1989) • They presented a 12-item list of words to subjects for free recall • After every word, the subjects heard the digits 1 through 9 presentation of the digits. • Ex) WL1 -> ND1 -> Recall ND1 -> WL2 -> ND2 -> Recall ND2 -> WL3 …

20. 3. Problems with the Modal Model① Continual distractor paradigm

21. 3. Problems with the Modal Model① Continual distractor paradigm

22. 3. Problems with the Modal Model② Ratio Rule • Ratio Rule • Bjork and Whitten(1974) suggested • This rules relates the size of the recency effect to the amount of time an item has to be remembered until recall and the amount of time that separates the items in the list • Two time measurements • Time between the presentation of list items (known as the interitem presentation interval or IPI) • Time between the presentation of the final item and recall test (known as the retention interval or RI) • The measure of recency used is the slope of the best-fitting straight line over the last three positions.

23. 3. Problems with the Modal Model② Ratio Rule

24. 3. Problems with the Modal Model② Ratio Rule • The ratio rule suggests that the absolute amount of time that an item has to be remembered is not important. • Instead, the recency effect should be similar when the ratios are similar : IPI:RI ->1s : 1s, 1min : 1min, 1hr : 1hr • Indeed, some recency effects have been observed when the IPI and RI are measured in weeks or years.

25. 3. Problems with the Modal Model③ Changing distractor effect • Changing distractor effect • Some researchers have tried to save the modal model • Koppenaal and Glanzer (1990) noted : • Because of the extensive practice on the task, subjects might be able to learn to time-share, alternating their processing between rehearing the list items to keep the last few in short-term memory and performing the distractor task. • Thus, if the type of distractor task is changed, the recency effect should no longer be observed.

26. 3. Problems with the Modal Model③ Changing distractor effect Surprise free recall test

27. 3. Problems with the Modal Model③ Changing distractor effect • This result is problematic for Kopenaal and Glanzer’s accout : • There should have been no information left in STS and thus no recency. • Even if there were recency, there should be no effect of changing the distractor, because there was no rehearsal to disrupt.

28. 3. Problems with the Modal Model③ Changing distractor effect

29. 4. Summary of the Modal Model • The two reasons for this in-depth explanation about modal modal are that : • The modal model has exerted more influence on memory research for a longer time than any other view • The modal model is far more sophiscated than many descriptions suggest, with several formal mathematical versions. • The modal model cannot account for : • The results from the continual distractor • The related ratio rule • The changing distractor effect

30. Thank you. ^^