What is Short-Term Memory?

STM Task vs. ST Processing

An Important Distinction!!

Each memory model will have its own account of processing for STM Tasks

The Modal Model Vs. The Working Memory Model

The phonological loopThe visuospatial sketchpadThe central executiveThe episodic buffer

Modules in the Modified WM Model

Approaches to Testing the Model

Dual tasks including concurrent vocalization, repeating random digits, visual scanning, etc.

Double DissociationsBoth with case studies & in normal populations using a concurrent task

Delays

Converging Operations

Some ExamplesClinical Cases Some patients do poorly on STM tasks but well on LTM tasks Others do well on STM tasks but poorly on LTM tasks

A Double Dissociation!!

Inferences to Best Explanation??

Some patients do well on digit span but poorly on the Corsi spatial spanOthers do poorly on digit span but well on the Corsi spatial span

Another Double Dissociation!!

Concurrent memory task effects on verbal reasoningConcurrent task: repeating sequences of random numbers

Verbal reasoning example: A follows BBA (true/false?)

Error rate unaffected

Inference to Best Explanation?

Baddley study using a pursuit rotorA spot of light moves along a circular path & the subject has to track it with a stylusThis tracking became the concurrent task

Subjects had to learn a list of words using either an imagery technique or a verbal rote memory technique

Imagery better except when performing the concurrent tracking task

Inference to Best Explanation??

Daneman & Carpenter, 1980

Measuring working memory span using prose memoryTask: verify a sequence of sentences & then recall the last word of each

Inference to Best Explanation? The episodic buffer

Baddeley et al, 1975

The word length effectTask: immediate memory for sequences of wordsResults: 1) memory declines as words become longer 2) subjects who rehearse rapidly tend to have longer spans 3) disappears with articulatory suppression

Inference to Best Explanation? The rehearsal process operates in real time.

Memory span set by two factors: • the rate at which the memory trace fades• the speed at which items can be rehearsed

Chess ResearchModerate vs. Expert Chess players viewed chess boards with pieces places on the board & then had to recall them

Dual task methodology used:• articulatory suppression• spatial tapping• generation of number sequences• none

Results:•Memory highly correlated with chess skill•Both groups showed no interruption from articulatory suppression•Both groups showed a moderate degree of interruption from spatial task•Both groups showed a substantial drop when random number generation was required

Inference to Best Explanation? Attentional control through the central executive is limited in capacity

The Case of Jeremy

How well does the working memory model vs. the modal model account for Jeremy’s problems?