Memory

1. Memory Short-term/Working Memory

2. Basic info-processing model of memory • Atkinson-Shiffrin 1968 • The modal model Sensory Registry Short-Term Memory Long-Term Memory Attention Rehearsal

3. Sensory Memory • Recall Sperling • Participants view a briefly presented array of letters. • Tone cued participants to recall items. • Change the duration between presentation of array and the recall tone

4. Sperling • Full-report paradigm • Report as many items as possible • Recall (no delay) = 3-4 items • Recall decreased with short delay • Partial-report paradigm • Tone cued which line of the array to recall • High = top line • Medium = middle line • Low = bottom line • Compare recall across rows

5. Partial-report paradigm • Recall with no delay roughly ~3 regardless of row • Same pattern of results with tone delay • All information gets in • Lasts a short time • Sensory memory is rather large but has a short duration

6. Short-term memory • The theory of STM was brought about during the cognitive revolution and is a product of the information processing perspective • It proposed that attended information went into an intermediate short-term memory where it had to be rehearsed (processed) before it could go into a relatively permanent long-term memory. • STM is biased toward keeping recent information available and has a limited capacity to do so. • Memory span - the number of elements one can immediately repeat back

7. Short-term memory • In a study of memory span, participants might rehearse digits by saying them over and over again to themselves. • With each rehearsal of an item, it was assumed there was a probability that the information would be transferred to a relatively permanent long-term memory. • If the item left short-term memory before a permanent long-term memory representation was developed, however, it would be lost forever. • One could not keep information in short-term memory indefinitely because new information would always be coming in and pushing out old information from the limited short-term memory.

8. One of the questions with STM regarded its duration • What determines the duration of STM? • Decay? • Gradual loss of memory “strength” over time. • Interference? • Access to information is blocked by the retrieval of other information • Overwriting? • Original memory trace is altered

9. Decay • Brown-Peterson Task • Use unrelated information • ‘T’ ‘K’ ‘B’ • “wood” “dog” “candy” • Many study-test trials • “You will not be shocked in this experiment” • Paradigm • Study three items • Count backward by 3’s • Prevent rehearsal • Vary duration of counting • Recall studied items

10. Brown-Peterson 100 • Decay • (on average) memory information is accessible up to 18 seconds. Proportion of correct recalls 0 1 18 Interval of counting (sec.)

11. Decay • Reconcilable with sensory memory • Use it or lose it. • Once memory is established, decay is constant • What constitutes “established?” • Is it always 18sec.?

12. Interference • Memory is more active • Newly encountered information (if used) limits the access to previous information. • Interference is often confounded with “decay”

13. Interference • Waugh & Norman (1965) • Present a set of 16 digits at a fixed interval. • 1 digit per second • 4 digits per second • Last digit in the set served as a probe, and had previously been presented once • Report the digit that appeared after the probe digit had appeared in the list the first time (target). • Manipulate the number of digits that appear between target and the probe. • Retention interval

14. Waugh & Norman • 1 per sec. Condition ? 9 ? 7 1 5 9

15. Waugh & Norman • 4 per sec. Condition 1 4 5 8 ? 9 ? 8 1 3 6 3 3 9 4 7 2 7 5

16. Waugh & Norman • If forgetting is a function of decay (time) then there should be less recall for slower rate (16 secs) vs. faster rate (4 secs) • If interference then should be little to no difference between the two.

17. Waugh & Norman 100 Proportion Correct 1 Cond. 4 Cond. 0 1 13 Number of items between target & probe More about the number of items that interfered rather than decay over time

18. Interference • So the Waugh and Norman results suggest interference from additional information can disrupt memory for particular items • Two types of interference • Retroactive Interference • New information interferes with previously learned information • Proactive Interference • Previously learned information interferes with the acquisition of new information

19. Retroactive Interference & Proactive Interference • Two-list paradigm • Paired associates • Two items paired with same target across lists • Probe with target

20. Retroactive Interference & Proactive Interference List 1 List 2 A - B A - C DOG - BALL DOG - WIRE Retroactive Later learning interferes with previously learned material B (ball) A ??? C (wire) Proactive Prior learning interferes with material learned later

21. Release from PI (Wickens, 1972) • Design • Given three items of a particular category • Countdown • Recall • Repeat with new category exemplars a 2nd and 3rd time • 4th time repeat or give three from a new category • Recall goes back to original levels with new category

22. Very Rapid Forgetting • Sebrechts, Marsh, & Seamon (1989) based on Muter (1980) • Used a modified Brown-Peterson paradigm with false trials. • B-P task • Acoustic (shallow) • Long E sound? • Semantic • Is it animate? • Reading • say the stimuli aloud • Exp 1 regular B-P experiment • Exp 2 “Surprise” memory test

23. Ss presented words sequentially and made a yes/no decision for each word presented or just read aloud depending on condition Countdown followed Sebrechts, Marsh, Seamon Brown-Peterson trial WOOD KEY TIME 382 Recall

24. Proportion of words recalled* LOP Expect Non-Exp Reading .73 .52 Semantic .55 .35 Acoustic .44 .27 Sebrechts, Marsh, & Seamon • Forgetting within 6 seconds • Expectation of retrieval is necessary to maintain information in memory, but also elaboration can have an effect • So again the idea of decay doesn’t provide for the whole story 100 B-P Proportion Recalled Surprise Trials 0 1 18 Interval of counting (sec.) *They looked also at the strict scoring i.e. remembering the whole trigram, the pattern was the same but with poorer performance overall

25. Interference • A possible explanation for interference is that when given cue, information associated with cue interferes with other info also associated with cue • More items a cue is stored with the less effective it will be in retrieving any one particular item • Recall fan effect • But along with interference as another possible explanation of forgetting, the Sebrects et al., shows other factors will have a say in how forgetting occurs • Expectancy • ‘Depth’ of encoding

26. The decline of STM • The idea of a short-term passive ‘store’ fit in with the current information processing models • Rapid forgetting • Transient nature suggests different type of store • Amount of rehearsal controlled the amount transferred to LTM • More rehearsal more remembering • Info had to ‘do time’ before getting to LTM

27. The decline of STM • Problems • Loss similar for better learned material (initial rapid loss followed by slower loss later) • Rehearsal by itself won’t determine what makes it to LTM: • Chunking • 7 + 2 • What may be chunked and how chunking occurs can depend on a variety of factors and varies across individuals • Depth of processing (Craik & Lockhart, 1972) • The Sebrechts article was an example of how DoP had a role even if there was decay • Some experiences gain immediate access to LTM • E.g. traumatic events • Such findings suggest there is more to short-term memory functioning than as a passive storage device until information makes it to LTM through rehearsal or just goes away

28. Working Memory • Function = short-term retention and manipulation of information. • Active memory • Issues regarding working memory • How long? • How much? • What type? • Capacity • Forgetting curve (Brown-Peterson) • Miller’s 7 +/- 2

29. Capacity • Measured by span • The number of items reproducible over a short interval. • Incrementally add items to a memory set. • Span varies … • Among individuals • Individual Differences • Across types of information • Rhyming > Non-rhyming • Digits > Words • Pictures > Labels

30. Baddeley • Model of WM • Based on perceptual codes • Acoustic • Visual and Spatial • Information can be retained separate from its use for a short time • Coordinating process guides the use of retained information • Central Executive • “Slave” systems • “Rehearse” information for a short time • Perceptually based

31. Central Executive Visuo-Spatial Sketchpad Phonological Loop Baddeley’s Model of WM • Central executive • Coordinates the Slave Systems • Response Selection • Guides Attention Maintains visual and spatial information Maintains acoustic information

32. Central Executive Visuo-Spatial Sketchpad Phonological Loop Baddeley’s Model of WM • Brown-Peterson Task • CE attends to memory set elements • CE “stores” memory set in phonological loop • PL attempts to rehearse the memory set during distraction • CE involved in distractor task (calculation) • CE coordinates retrieval from PL during recall

33. Phonological Loop • Two components • Phonological store • Articulatory control process • Subvocal articulatory rehearsal • Traces within the store decay over a period of about two seconds unless refreshed by rehearsal, a process akin to subvocalization and one that is dependent on the second component, the articulatory system • Important for long-term phonological learning • e.g., language learning

34. Some evidence for the loop • Phonological similarity effect • PGTVCD vs. RHXKWY • Similar phono code leads to confusion • Irrelevant speech effect • Colle & Welsh (1976): even a foreign language can interfere with immediate recall of items • Because of the nature of the code, the language gains access to the phono store • Articulatory suppression • Operation of the loop is disturbed if overt or cover articulation takes place • Vocalization utilizes same system as subvocal rehearsal, and hence can lead to difficulty learning verbal information • Word length effect

35. Word-length Effect • Span decreases as the length of a word increases • Less can be rehearsed within the ~2 sec time frame DOG HOUSE BAT GLASS WOOD BIKE ASSOCIATION PARLIAMENT CONCENTRATION EMPOWERMENT

36. Visuo-spatial Sketchpad • Temporarily maintains and manipulates visuospatial information • Plays an important role in spatial orientation and in the solution of visuospatial problems • Both visual (imagery) and spatial component • Possibly two different systems

37. Some evidence for the sketchpad • Baddeley & Lieberman (1980) • Visual tracking interferes with imagery mneumonic • Irrelevant picture effect • Same result even from just looking at visual stimuli

38. Central Executive • Most complex and least understood component of WM • Model suggests CE coordinates the activity of the two slave systems • Other potential roles • Coordinating retrieval strategies • Selective attention • Suppression of habitual responses • Task switching • Temporary activation of long term memory • Binding of sensory and conceptual information

39. Assumptions and Predictions • Slave systems are independent of each other • It is possible to do a both a verbal task and a spatial task at the same time • Extremely difficult to do two verbal (or two spatial) tasks at the same time. • Dual-Task Paradigm • Participant must perform more than one task at a time • Slave systems have limited capacity • Span • Slave systems can function autonomously from the Central Executive • Can do “Central Executive tasks” and slave system tasks at the same time • Central Executive coordinates information based on current goals • Implies intentional (conscious) control of WM • Coordination involves many processes.

40. Questions regarding the WM model • Articulatory suppression: • AS should prevent registration of visual material (which must be recoded phonologically) • In fact, span only drops slightly • How is this material stored? • Chunking: • Presumably info in LTM is used to chunk • How is this information integrated?

41. Questions regarding the WM model • Rehearsal • Does rehearsal have to be subvocal? • How are items in VS rehearsed? • What about children? (they do not spontaneously rehearse subvocally) • The role of consciousness • CE originally proposed to assist in binding - our ability to integrate information about location, color, size, smell, feel etc of objects. • How could it do this without a multimodal short term store?

42. The Episodic Buffer • “A limited capacity temporary storage system that is capable of integrating information from a variety of sources” • Controlled by the CE • Feeds information into and retrieves information from LTM • Uses a common “multidimensional” code • The Episodic Buffer makes the link between Working Memory and LTM more explicit

43. Working Memory today