Organization of Working Organization of Working Memory—Reconciling Two Memory—Reconciling Two

Different ModelsDifferent Models

Anna AlapattAnna Alapatt

Working Memory (WM)Working Memory (WM)

Working memory holds information in a rapidly accessible and easily updated state

E.g. Getting dressed in the morning

Core cognitive ability—predicts intelligence (IQ & scholastic achievement)

3-4 slots for most people (Luck & Vogel, 1997).

What is Visual Short What is Visual Short Term Memory (VSTM)?Term Memory (VSTM)?

Sample array Test arrayOnset Delay

900ms100ms

Fixation Encoding Storage Comparison

•Previous research has shown that people can maintain 3 to 4 items in VSTM through change detection tasks.

Two hypotheses about how Two hypotheses about how WM is organized WM is organized

General resource model—no matter General resource model—no matter what is being remembered a single what is being remembered a single common resource determines common resource determines memory capacitymemory capacity

Many resource model—there are Many resource model—there are multiple types of working memory multiple types of working memory depending on what type of depending on what type of information is being storedinformation is being stored

WM..Many ResourcesWM..Many Resources

Domain specific slotsDomain specific slots

Baddeley Model—Baddeley Model—many resourcesmany resources

Baddeley’s Model of Memory

WM..One ResourceWM..One Resource

Domain General Slots

Cowan Model

Focus of attention

Activated Portion of LTM

Cowan’s Memory Model

General QuestionGeneral Question

Awh, Barton, Vogel (2007), have Awh, Barton, Vogel (2007), have suggested there might be two distinct suggested there might be two distinct abilities within visual working memory: abilities within visual working memory: 1) number 2) precision/resolution 1) number 2) precision/resolution

Is it possible one aspect (e.g., number) Is it possible one aspect (e.g., number) is domain general, and the other (e.g., is domain general, and the other (e.g., precision) domain specific?precision) domain specific?

Current Study—2 aspects of Current Study—2 aspects of memory abilitymemory ability

Used motion & color as examples (both Used motion & color as examples (both processed in distinct parts of visual processed in distinct parts of visual cortex)cortex)

Reconcile the 2 different modelsReconcile the 2 different models

PredictionsPredictions: :

Cowan’s Cowan’s domain generaldomain general model may be correct with model may be correct with respect to respect to numbernumber

Baddeley’ Baddeley’ domain specificdomain specific model may be correct model may be correct with respect to the with respect to the precisionprecision of the memory of the memory representations.representations.

Experimental DesignExperimental Design

Sample Array Test ArrayDelay Interval

Time

1 second 1 second Until Response

The number of motion stimuli that The number of motion stimuli that could be stored was reliably correlated could be stored was reliably correlated

with the number of colors.with the number of colors.

R2 = 0.16

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

0.00 1.00 2.00 3.00 4.00

motion recall K

colo

r K

This correlation is consistent with Cowan’s stimulus-general This correlation is consistent with Cowan’s stimulus-general model of capacity in working memory.model of capacity in working memory.

These data fall more in line with the hypothesis that color These data fall more in line with the hypothesis that color and motion memory are supported by separate and motion memory are supported by separate resources. resources.

Supports Baddeley’s modelSupports Baddeley’s model

R2 = 0.07

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

0.00 10.00 20.00 30.00 40.00 50.00 60.00

precision of motion recall

colo

r K

The precision of motion recall did The precision of motion recall did notnot predict how many colors could be predict how many colors could be

stored in working memory.stored in working memory.

DiscussionDiscussion The number of motion patches and the The number of motion patches and the

number of colors stored in working memory number of colors stored in working memory were correlated. This suggests a common were correlated. This suggests a common resource mediating how many things can be resource mediating how many things can be stored in working memorystored in working memory

The precision of motion memory was not The precision of motion memory was not correlated with the number of colors they correlated with the number of colors they could store. This suggest that number and could store. This suggest that number and precision are different aspects of memory precision are different aspects of memory ability, and leaves open the possibility that ability, and leaves open the possibility that Baddeley’s multiple resource model is correct Baddeley’s multiple resource model is correct with respect to the precision of with respect to the precision of representations in working memory. representations in working memory.

Future DirectionFuture Direction

This is all a part of a project to look This is all a part of a project to look at many different stimuli at many different stimuli (orientation, motion, etc.) and see (orientation, motion, etc.) and see how number and resolution relate how number and resolution relate across different types of information across different types of information processedprocessed

Thanks….Thanks….