Memory 3265

1. Memory 3265 • Course website address • http://www.yorku.ca/npark/memory_f_17

2. Short-term working memory • James, Galton, and others have proposed a memory system that keeps in consciousness a small number of ideas • William James referred to this system as primary memory • the primary memory is probably more closely related to working memory than to STM

3. Short-term working memory • Short-term memory capacity is measured using a memory-span procedure • Memory span procedure: participant presented a sequence of items, and is required to repeat them back; start with one item, increasing the number of items by 1 until the participant makes mistakes

4. Short-term working memory • the point at which the participant is able to recall all items correctly 50% of the time is designated as her/his memory span • factors affecting memory span • auditory presentation leads to larger memory span estimates than visual presentation • rhythmic presentation is better than non-rhythmic presentation

5. Short-term memory • The next slide contains a series of digits. The digits are presented in pairs. Read the pairs of digits rhythmically aloud. Pause between each pair. For example, suppose the digits were • 24 89 17 14 29 12 3 • After you have read the pairs aloud, I want you to write down as many digits as you can remember. Any questions?

6. Read aloud these digits • 41 64 00 40 11 49 2

7. Short-term memory • I want you to write down as many digits as you can remember. Any questions?

8. Read aloud these digits • 416 400 401 1492

9. Short-term working memory • factors affecting memory span (cont’d) • recoding or chunking information; George Miller showed in his classic paper (1956) that memory span is determined by the number of ‘chunks’ or integrated items to be recalled, not the number of items presented

10. Inducing rapid forgetting • Brown-Peterson paradigm • Brown (1958) and Peterson & Peterson (1959) showed that very rapid forgetting is possible • paradigm • study: present a small number of items followed by a number such as 632. Participant is required to count backward by threes until given a recall signal. Then he/she attempts to recall studied items

11. Inducing rapid forgetting

12. Inducing rapid forgetting • Note: Murdock (1961) showed that performance is about the same for 3 consonants as it is for 3 words, illustrating the importance of chunking • why is information forgotten in the Brown-Peterson paradigm?

13. Inducing rapid forgetting • why is information forgotten in the Brown-Peterson paradigm? Two possibilities • trace decay: automatic fading of memory • interference: memory is disrupted by other memory traces

14. Inducing rapid forgetting • Two types of interference • proactive interference: effects of prior items on recall of subsequent items • retroactive interference: effects of subsequent items on recall of previous items

15. Inducing rapid forgetting • why is information forgotten in the Brown-Peterson paradigm? • Petersons argued that it must be trace decay; it couldn’t be retroactive interference because numbers are very different from consonants • Keppel & Underwood (1962) showed that proactive interference seemed to be responsible because if performance on the first trial only is examined there is little decline in performance over the retention interval

16. Inducing rapid forgetting • Further evidence for the importance of proactive interference (PI) • release from PI • numerous studies have established that if you present several lists of items using a Brown-Peterson procedure (Study: present list of 3 items; count backwards by 3s for 15 sec, then attempt recall of the studied items. Results show that performance declines across lists

17. Inducing rapid forgetting • Results show that performance declines across lists (build up of PI) • If categories studied are changed, then recall of the changed category increases (release from PI)

18. One or two memory systems • Are STM and LTM distinct? • One approach to investigating this question involves determining whether certain tasks have separable components • One task is free recall

19. Free Recall performance (Craik, 1970)

20. Interpretation of free recall study • Primacy and intermediate components of the serial position curve are lower in the delayed compared to immediate condition • Key result: recency portion of the curve is differentially lower in the delayed condition • interpretation: delayed condition has a stronger influence on recency portion of curve because recency reflects STM

21. Neuropsychological Evidence for separation of STM and LTM • Data from amnesics support distinction between STM and LTM • Evidence: amnesics have normal digit span, which is mediated by STM, but are impaired in their ability to acquire and retain LTM memories

22. Neuropsychological Evidence for separation of STM and LTM • Free recall data in amnesics also supports this distinction. • predict performance of amnesics (Baddeley & Warrington, 1970) • In immediate free recall, how should amnesics perform on the recency portion of the curve? • What about the primacy portion of the curve?

23. Short-term working memory • Atkinson-Shiffrin model of memory (1968) • distinguishes between two types of memory: short-term and long-term memory • short-term memory (STM): a temporary storage system capable of holding a small amount of information (e.g., telephone number) • information in STM is forgotten quickly unless it is rehearsed or transferred into LTM • Long-term memory (LTM): a permanent memory store with no capacity limitations

24. Atkinson-Shiffrin model of memory Rehearsal Incoming information Short-term memory Long-term memory Transfer Information displaced

25. Problems with modal model • Atkinson-Shiffrin model assumes that STM plays a critical role in the transfer of information into LTM • Specifically, this model suggests that the capacity of the STM should determine the probability that an item enters LTM and • The amount of exposure in STM should affect the likelihood that an item enters into LTM

26. Problems with modal model • Both these implications are incorrect • several studies have shown that under some conditions the number of times material is rehearsed is a poor predictor that it will be recalled subsequently (shallow rehearsal)

27. Problems with modal model • Shallice and Warrington (1970) and others have established that at least some people with poor memory span (this suggests that STM is damaged) have normal long-term memory • KF had impaired memory span (KF memory span WAIS score = 2, Mean = 10, Standard deviation = 3 • KF’s long-term memory performance was unimpaired

28. Summary • Evidence supporting STM vs LTM distinction • tasks such as free recall seem to have both STM and LTM components • Neuropsychological evidence suggests that both components can be selectively damaged • amnesics have damaged LTM component, but intact STM component • KF (and others) have damaged STM but intact LTM

29. Summary • However, the modal model (Atkinson-Shiffrin) does have problems accounting for • the finding that patients with STM deficits appear to have intact LTM • maintaining an item in STM does not ensure its transfer to LTM

30. Working memory model of Baddeley • A different conceptualization of STM • Baddeley hypothesized STS is important because it acts as a working memory, a system that is important for holding and manipulating information • Hypothesized working memory needed for a broad range of cognitive tasks

31. Working memory model of Baddeley • Experimental paradigm (dual task paradigm) • primary task: grammatical reasoning • Determine whether sentences are true/false • e.g., A follows B -- BA (true) • e.g., B is not preceded by A - AB (false) • secondary task: concurrent digit task: remember number sequences ranging in length from 0 to 8

32. Baddeley (1986) cont’d • Results • reasoning time increased with concurrent digit load. However, performance remained high, and errors remained low (about 4% and did not vary with digit load); see figure • thus, overall performance remains quite good, even when the overall digit load is 8 (memory span capacity)

33. Baddeley (1986)

34. Baddeley (1986) cont’d • Conclusions • Hypothesized two systems are involved in this task • One system stores digits (phonological loop) • A second system manipulates information in the reasoning task (central executive) • See Baddeley’s working memory model

35. Baddeley’s working memory model Visuo-spatial sketchpad Phonological loop Central Executive

36. Working memory model of Baddeley • Basic model of working memory consists of a controlling attentional system (called the central executive) and two slave systems, an articulatory or phonological loop system and a visuo-spatial sketch pad

37. Working memory • Phonological loop characteristics • consists of a phonological store (codes speech-based information), and maintains information for about 2 seconds • articulatory control process that refreshes items in store by means of subvocal rehearsal

38. Working memory • Phonological loop • appears to play an important role in reading • poor readers tend to have poor short-term memory span • also appears to play a role in the comprehension of language and in the acquisition of vocabulary

39. Visuo-spatial sketchpad • Information can enter the sketchpad visually or through the generation of a visual image • access to this store by visual information is obligatory • the information in this store may be visual or spatial or both

40. Central Executive • The central executive plays an important role in controlling attention.

41. Central Executive • Vigilance • recall vigilance refers to sustained attention • Parasuraman (1979) showed that vigilance performance decreases if the vigilance task has a short-term memory component involving storage and manipulation of information.

42. Central Executive • Vigilance • Experiment • Condition 1. discriminate between successive tones of various volumes (requires memory) • Condition 2. discriminate between simultaneous tones of various volumes (no memory required) • Performance declined in condition 1 but not condition 2

43. Central Executive • Vigilance Conclusion Performance declines over time if task requires working memory

44. Central Executive • Effects of dividing attention on declarative memory performance • Studies showed that performing a concurrent task during the encoding phase of a declarative memory task (e.g., a list of words), reduced recall of studied words compared to encoding words a full attention • Dividing attention during recall of the studied words had a small effect on performance compared to recall at full attention

45. Central Executive • Effects of dividing attention on declarative memory performance • Conclusion. Encoding words into declarative memory requires working memory. Retrieving words from declarative memory does not appear to require working memory (Baddeley, Lewis, Eldridge, & Thomson, 1984)

46. Central Executive • Effects of dividing attention on procedural memory performance • Roy & Park (2016) investigated the effects of dividing attention on declarative and procedural aspects of novel tool use. • Participants trained to use a set of novel tools under full and divided attention

47. Central Executive • Effects of dividing attention on procedural memory performance

48. Central Executive • Effects of dividing attention on procedural memory performance • Results showed that dividing attention did not interfere with motor skill learning, a type of procedural memory • Conclusion. Encoding skilled actions into memory does not appear to require working memory

49. Episodic buffer of working memory (Baddeley’s new model) • Overview • recently Baddeley updated the 3-component model of working memory • It proposes a 4th component, an episodic buffer • It has limited capacity • Stores information in a multimodal code • Binds information from subsidiary perceptual systems and LTM into episodic memory • Information is consciously retrieved

50. Episodic buffer of working memory (Baddeley’s new model) • Background • 3 component model of working memory consists of central executive and two slave systems, the phonological loop and the visuo-spatial sketchpad • Central executive is an attention controller • Phonological loop stores speech-based info • Visuospatial sketchpad stores visual info