Memory

1. Memory How does memory work?

2. The Modal Model • 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 • Partial report suggested sensory memory is rather large but has a short duration

4. 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

5. 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

6. Short-term memory • 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

7. Decay • Brown-Peterson Paradigm • “You will not be shocked during this experiment” • Study unrelated information • ‘T’ ‘K’ ‘B’ • “wood” “dog” “candy” • Count backward by 3’s • Prevent rehearsal • Vary duration of counting • Recall studied items

8. 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.)

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

10. 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

11. 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

12. 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

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

14. 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 • 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

15. 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

16. 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

17. 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 Sebrechts et al., shows other factors will have a say in how forgetting occurs • Expectancy • ‘Depth’ of encoding

18. 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

19. 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 suggested there was more to short-term memory functioning than as a passive storage device

20. 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

21. 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

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

23. 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

24. 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 • Span decreases as the length of a word increases • Less can be rehearsed within the ~2 sec time frame

25. 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

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

27. 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

28. 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.

29. 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

30. Working Memory Today

31. Long-term memory • Basically includes anything retained that did not occur few moments earlier • Source of information that does not come from the environment

32. Learning • Storage of information in memory as a consequence of experience • Process of acquiring new associations among stimuli, responses and outcomes. • What is Learned? • How is it Learned? • Associative theories • Learning • Cognitive theories • Encoding and Retrieval

33. Classical Conditioning • Characterized by the generalization of a fixed or previously learned behavior • Responses are elicited from stimuli • Unconditioned stimulus (US) • Elicits a response without training • Shock • Unconditioned Response (UR) • Elicited without training by a (US) • Smacking whoever gave you the shock • Conditioned Stimulus (CS) • That which through training elicits a particular response • Pretty flowers • Conditioned Response (CR)* • Response to the conditioned stimulus • Smacking whoever gives you pretty flowers

34. Operant / Instrumental Conditioning • Based on the principle of reinforcement • What is reinforced? • What is reinforcing? • Development of associations between particular responses and consequences of the response (outcomes).

35. Basic Mechanisms of Operant Conditioning • Behaviors have consequences • Consequences are contingent on behaviors • Organisms adapt behavior to match contingencies • Consequences usually satisfy a “drive” • Biological need • Motivational need • Well-being of individual

36. Consequences of Behavior • Reinforcement or Punishment • Reinforcement • Consequences of behavior increase the probability of response (behavior) • Punishment • Consequences of behavior decreases the probability of response • Both Reinforcement and Punishment can be positive or negative • Positive: presentation of stimuli • Negative: removal of stimuli • The result is a table of contingencies…

37. Reinforcement and Punishment Response Increase (rein.) Decrease (pun.) Positive Reinforcement (reward) Positive Punishment (punishment) Apply a stimulus (+) Stimulus Negative Reinforcement Negative Punishment (omission) Remove a stimulus(-)

38. Associative Learning • Accounts for certain types of memory phenomena • Memory Structure • Highly practiced information • Habitual responses • Stimulus generalization • Assumes memory mechanism is the same as associative mechanism (single system)

39. Associative Memory • Associative memory theory alone cannot account so well for other phenomena • Free Recall • No cue • Subjective organization • Von Restorff Effect • Effect of stronger memory for a salient item in a series • Sensory Memory • “Direct” memory of sensory information • Short-term representations • No Practice • Complexity of language acquisition/production • Systematic memory distortions

40. Beyond association • Although simple associative mechanisms described by classical and operant conditioning may account for some aspects of learning, more was needed • Subtle shift from learning theories to theories of memory, which emphasized knowledge representation in an information processing system • Focused on encoding and retrieval processes to help explain memory performance in a variety of settings • Levels of Processing • Encoding specificity • Transfer appropriate processing

41. Basic Mechanisms of Memory • Encoding • Acquisition of Information • “Learning” ? • Maintenance • Retaining information • Retrieval • Using information • How do the processes of Encoding and Retrieval influence what is remembered?

42. Levels of Processing • Craik & Lockhart (1972) • Formalized the notion of “depth” of processing and demonstrated how it affects memory. • There are “depths” to which information can be processed • Shallow: encoding information in terms of its physical or sensory characteristics • Deep: encoding information in terms of meaning • Levels (for words) • Structural • Is it all caps? • Shallow • Phonetic • Does it rhyme with _? • Semantic • Is it an animal? • Deep

43. Levels of Processing 100 Proportion correctly recognized 0 CAPS? Rhyme? Animal?

44. Levels of Processing • Such results suggests that deeper levels of processing produce more permanent retention than shallow levels of processing. • Distinctiveness and elaboration may be responsible for the effectiveness of deep levels of processing • Other results • Intention to learn does not change LOP pattern of results (Hyde & Jenkins, 1973) • Generation effect (Slamecka and Graf, 1978) • Self-reference task encourages especially deep levels of processing (Rogers, Kuiper, & Kirker 1977 • Problem: What is “deep” and what is “shallow?” • Circular logic • If processing is deep then retention will be better. • If retention was better, then processing must have been deeper. • There is no precise way to measure ‘depth’

45. Encoding-Specificity Principle • Information is available to the extent to which retrieval cue matches encoding • Tulving and Thomson, (1973)

46. Morris, Bransford, & Franks (1977) • Had people make one of two judgments at presentation • Shallow: Rhyming (Does it rhyme with hat?) • Deep: Semantic (Does it have a tail?) • Two test conditions • Recognition • Rhyming • “Hat” • “Did you see a word that rhymes with X?” • Test Condition either matched or mismatched original encoding

47. TEST Rhyme Recognition - + Rhyme PRESENTATION - + Semantic Morris, Bransford, & Franks

48. Morris, Bransford, & Franks • LOP effect for standard test. • But opposite for rhyming test • Deep processing does not always enhance memory

49. Transfer Appropriate Processing • Memory performance depends on the extent to which processes used at the time of learning are the same as those used when memory is tested • LOP approach assumed that semantic processing was always superior to non-semantic processing • The transfer appropriate processing approach demonstrates that a form of encoding which is “shallow” for one purpose might be “deep” for another. • Conclusion • Memory not just a function of depth of processing • Depends also on the match between encoding processes and type of test

50. Interaction of Encoding and Retrieval • Context Congruency • Godden & Baddeley • Divers memorized a list of words • Half learned the words on dry land • Half learned words underwater • Tested either on dry land or underwater