Temporal Decay and Resource Sharing in Working Memory Span Measures:

A New Paradigm

Pierre Barrouillet

Valérie Camos

Sophie Bernardin

Université de Bourgogne

Université René Descartes - Paris V

Working Memory Span Tasks

• Maintenance of some information

• Simultaneous treatment

They involve:

The Counting Span Task (Case et al. 1982)

Participants are asked to:• Count arrays of dots• Maintain the results

The number of arrays increases until failure to recall

8

10

6

8 10 6

Counting span of 3

Recall

Working Memory Span Measures

• They predict performances on complex activities

• They strongly increase with age

Developmental increase:Alternative hypotheses

• Resource sharing - Case et al (1982)

• Temporal decay - Towse et al (1995, 1998)

The resource-sharing hypothesis:Case et al. (1982)

TPS

O STreatment

S T S SMaintenance

The resource-sharing hypothesis:The developmental effect

O STreatment

S T S SMaintenance

Increase of processingefficiency

The temporal decay hypothesis:Towse & Hitch (1995)

Duration of processing and maintenance

Probability of recall

With the development

Processing becomes fasterDuration of maintenance decreasesThen the span increases

The temporal decay hypothesis: Switching between Processing and Storage

P S P S P S

P S P S P S

Switching

Children

Adults

Duration of processing determines duration of maintenance because individuals switch from storage to processing thus leading to the decay of memory traces.

Time

The temporal decay hypothesis: A test

Towse, Hitch, & Hutton, 1998, 2000

Card 2 Card 3Card 1 Card 4

Card 2 Card 3 Card 4Card 1

Duration of maintenance

Long final condition

Short final condition

Higher span predicted

Results

Similar results with Counting Span and Reading Span

Operation Span

Short-final span > Long-final span

The temporal decay hypothesis: Are the evidences compelling ?

Card 2 Card 3Card 1 Card 4

Card 2 Card 3 Card 4Card 1

Duration of maintenance

Long final condition

Short final condition

Long final condition more costly than short final condition

WM task only begins at the end of card 1

A new paradigm:Barrouillet & Camos (2001)

Towse & Hitch:equated the cost while manipulating the duration

Barrouillet & Camos:equated the duration while manipulating the cost

A new paradigm:Barrouillet & Camos (2001)

Ope 4Ope 2Ope 1 Ope 3

ba ba baba ba baba ba ba ba ba ba ba ba

Operation span task

Baba span task

Time

F B TL

F B TL

Mean solutiontime foroperation 1

The results in children and adults:Barrouillet & Camos (2001)

No interaction with age

Conclusions from the first experiment

• We cannot jettison any notion of cognitive resource in accounting for performances in working memory tasks.

• Solving problems instead of saying « ba ba » did not result in any dramatic decrease in span.

• Individuals can switch attention from the operations to the letters to be remembered while solving operations

Prediction

• Tasks that would require continuous attentional focusing should have a detrimental effect on span

• Complex activities (e.g., reading, problem solving) are not needed as a processing component.

• We just need a task that captures attention.

A recipe for constructing working memory span tasks:

A new task : The Continuous Operation Span task

Read the letter, the number, and then perform the operations aloud

Try to remember the letters

A preview

R 4 +1 -1 +1

The red operand indicates that a new letter will appear

R

4

+1

-1

+1

H

9

-2

-1

Recall

The Reading Operation Span task

Participants perform the same task except that they just have toread the operations and their results

R 4 +1 -1 +15 4 5

Same duration as the Continuous Operation Span task

Test of our prediction in adults

Compare:

• Continuous Operation Span

• Reading Operation Span

• Baba Span: saying "ba" during the same duration

Prediction:

COS should be smaller than the ROS that should be smaller than the Baba Span

Results

All the differences are significant

Conclusion

• The time does matter but ...

• Working memory span depend strongly on the processing component the task involves

• There is no need to use complex activities to create working memory span tasks

• Cognitive cost = attentional demand

ConclusionCognitive Cost = Attentional Demand

(Engle et al., 1999)

To perform self-paced complex operations (7 + 9 + 8 = 23 ?) results in higher spans than ...

To perform computer-driven memory retrievals (+/- 1 or 2)

ConclusionContinuous Operation Spans are significantly lower than Operation Spans

Take Home Message

WM Spans strongly depend on Cognitive Cost

Cognitive Cost is Attentional Demand