Episodes, Time, and the Structure of Human Memory (!)

• On the agenda:– Finish discussion of

measurement in memory– Present results of search– Information-processing models

of human memory (Pashler)– Approaches to temporality– Binding elements of events into

episodes• Baddeley’s Episodic Buffer• Craik’s work on binding of

content and context– Settle on presentation

assignments

MEMORY STRUCTURESand PROCESSES

• The information-processing approach and its tools– Elements of Pashler’s model

• Functional level of constructs• Multiple sensory and STM

systems• Dissociative evidence• Tracking the flow of information

– Attentional gating of sensory input– Dual-task / RT methodology

• The Central Processor– Recoding in STM– I/O for episodic memory– Selecting actions and responses

CONTROL and CAPACITY inINFORMATION I/O

• STM Encoding– Voluntary selection among inputs

• Partial report tasks– Some contact with semantic LTM

in absence of such attention• “priming” without awareness

(e.g., Marcel, ’70?)– Little apparent “central”

interference• Free recall recency not affected

by card sorting (Murdock, ’65)• LTM Encoding

– Voluntary selection and selective rehearsal

– Elaborative encoding– Great “central” interference

• Tone decisions impair memory for concurrent events (Carrier & Pashler, 98?)

CONTROL and CAPACITY inINFORMATION I/O (concl)

• LTM Retrieval– Central demands can interfere

• Interference with retrieval from a speeded choice task (Carrier & Pashler, ’95)– Sequential task design– Use of Pschological Refractory

Period (PRP)– RT1 to tone; RT2 cued recall or

recognition– RT2 slowed by short SOA– Slowing is additive with retrieval

factors• May be limited to “strategic”

retrieval (Baddeley)

Carrier & Pashler 1995

• Pashler’s I/O model of Memory– Strong multi-system flavor

• Sensory, STM, LTM• Multiple STM systems

– Capacity and control limits at various stages• Selective attention and

bottlenecks• Capacity limits and the Central

Processor– Contrasts to other multistage

models• Atkinson & Shiffrin 1968• Bjork 1975• Potter 1983• Baddeley 1986

CREATING EPISODES:The Canvas of Time

• The issue of time perception– Relative contribution of attention,

events, and “biological time”– Speculations about bioclocks

• E.g., as marking of synchrony in striatum (Matell & Meck, ’00)

• Time perception (cont’d)– Evidence from patients

• Damasio, Tranel & Jones:– Cued recall of personal and public

events– Placement of events on “time line”– Temporal amnesics:

• Poor event recall, OK placement– Basal forebrain amnesics:

• Fair event recall, poor placement– Recent imaging evidence

• Rao, Mayer & Harrington ’00– Tone-pair standard 1200 ms– 1 sec IPI– Tone-pair time or pitch changed– Early activation of putamen, caudate

(basal ganglia)– Later activation of cerebellum

– Parkinsonism and the timer• Underestimation of intervals

(Malapani, ’98)

• Time perception (concl)– Attentional modulation of time

estimation• Non-temporal central tasks impair

accuracy of both prospective and retrospective interval estimates (S. Brown, ’85)

• General pattern is for underestimation of interval duration

Features, Objects,Events and Episodes: The

Binding Problem(s)• Hierarchical structure of episodes• Feature analysis and integration

– Feature Integration Theory (Triesman)• Attention required (mostly) for

search for conjunctions (Triesman & Gelade ’80)

Distraction can produce “illusory conjunctions” of features

T T T T T T T T T T

T T T F T T T T T T

T T T T F T F T T F

• Multimodal integration and temporal sequencing– The Episodic Buffer (Baddeley

’00)• The “classic” WM model• Problems

– Concurrent articulation, impaired phono-STM, leaves visual digit span of c. 4, not 1

– Impaired phono-STM patient has “sentence span” of 5

– Maintenance of complex images in WM

• The revised model:

• Interfering with the Episodic Buffer– Jeffries, Ralph & Baddeley (JML,

2004)• Dual-task approach• Immediate serial recall of words• Random words or unrelated

sentences• Alone or with concurrent visual 4-

choice RT (x z . /)

Word recall at 50% above span

0102030405060708090

100

Words Sentences Stories

Type of stimulus

Per

cent

Cor

rect

Single

Dual

• Neural basis of integrated WM– Prabhakaran ’00 fMRI study

• Integrated maintenance versus separate maintenance tasks– Letter sequence– Location of x’s– Location of letters

• Match location or letter• Match letter-in-location

• Only in last case, sees right prefrontal cortex activation

• Unintegrated maintenance shows more posterior activity

• Binding events to their context– Craik ’89: Making of episodes

• Importance of the “spatiotemporal context” of objects and actions

• Does binding of event to context require attention?– Present items (words, pictures)– In varied contexts (scenes, voices)– Manipulate attention– Track memory for items and context

• Generally, tight coupling of item and context memory

• Suggestion that attention plays a greater role for “poorly integrated” item-context associations at retrieval

• And leads to better integration at study

Context identification

Item

reco

gniti

on

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