Divided attention

Chapter 3

IntroductionDual task experimentsTheoriesSingle or multiple processors?Summary

Introduction

Doing two things at onceEveryday experienceDual tasks

Dual task experiments

Eysenck & Keane(1995) have identified three major factors that affect the ability to do two(or more) tasks at once

① Task similarity② Task difficulty③ Practice

Task similarity

Allport et al.(1972):shadow prose and learn a list of words(recall)

① Present to the other ear(poor)② Print on a screen③ Present as pictures on a

screen(very good)It is a difficult concept to define

Task difficulty

inter-individualintra-individualCombine with a second task

Practice

Spelke et al.(1976):write down dictated words while reading short stories

Reasons1. Reduce the amount of resource2. Help participants learn

strategies

Theories

Central capacity theory

Kahneman(1973)Attention as a skill rather than a

processMental effort=tasks require different

processing capacityThe difficulty of the task & the degree

of practice

Central capacity theory

Arousal

AvailableCapacity

AllocationPolicy

Possible Responses

Response

EnduringDisposition

s

Momentary

Intentions Evaluation of Demandson Capacity

Kahneman(1973)central processor

Evaluation

Task difficulty, the role of practice and arousal

Problems1. The limits of capacity2. Does not explain the strong

influence of similarity

Central capacity interference theory

Norman and Bobrow(1975)Resource-limited & data-limited

Evaluation

Cherry(1953)Failure to predict performance of

tasks in experimentsNon-falsifiable

Multiple channel theories

A limited capacity model

A central processor

Dealing with many different types of task required by an attentional system ?

Dealing with all attentional tasks?

Explaining the complex nature of attention

(Neisser, 1976 ; Allport, 1993) ?

A single filter

•It is difficult to see how the neurology of the brain could produce a system of processing a capacity (Hampson and Morris,1996)

Allport – modules of attention

Attention consists of a number of specialised modules (Allport, 1980,1983) Each module deal with a different ability or skill Each module has its own resources and a limited

capacity Wicken, 1984

Different modules may deal with different aspects of a task

Modules exist for input/processing/output mode

(1)Listening to a massage

(2)List of words to be learned

(3)Shadowing message

(1)Listening to a massage

(1)List of pictures to be learned

(3)Shadowing message

Evaluation of module theory

To explain the effects of similarity in dual task experiments

(Allport et al.,1972Treisman and Davies, 1973)

Evaluation of module theory

The fundamental assumptions of cognitive neuropsychology Relatively independent cognitive

processors or modules Each one can function to some extent in

isolateion Brain damage (Eysenck and

Keane, 1995) Only some of these modules are impaired

Evaluation of module theory

Problem 1 It doesn’t specify the

number of modules What types of

modules they are?The theory is

therefore non-falsifiable

Problem 2 How the modules

work together? How the modules are

co-ordinatedEnough practice

The similar tasks can work concurrently

Competing for the resources of one module

(Underwood, 1974; Spelke et al., 1976)

Multiple Resource Theory

Navon & Gopher (1979)- specialized “mental resources” (like modules)- performance can be traded (new concept)- supply and demand

Good explanation of effect of task similarity in dual task experiments (Allport et al, 1972)

Multiple Resource Theory

Input

• Stimuli

Processing Information

• Transformation

Response

• Output

Multiple Resource Theory

Drill

SawsLathe

s

Raw Material

Finished

Product

Drill

Multiple Resource Theory

Dawson and Schell (1982) Shadowed a message Classically conditioned word in non-attended ear

(left or right) Conditioning = paired with mild electric shock Subsequent recognition = autonomic nervous

system response Left vs. right hemisphere - Left for speech

reception and production - Right for speech analysis

Automated response to unattended message in left ear but not right ear

Multiple Resource Theory

Payne and Wenger (1998) Single capacity model

= response in both ears or neither Multiple resource model

= response to each ear differently Not able to detect unattended message in right ear Left hemisphere is for speech reception and

production, and primary task (shadow message) takes priority

Not enough resources to analyze unattended message at the same time

Multiple Resource Theory

Failure to specify number of resources

How the multiple resources work together

Attentional processes highly integrated

HOW?

Single or Multiple Processors?

Flaws with both models Single capacity models fail to account for

effect of similarity in dual task experiment Multiple capacity models fail to explain

how different parts of attention work together

Single or Multiple Processors?

Baddeley (1986) Synthesis theory

- combine features of both approaches- central, limited capacity processor(from central capacity theory)- modality-specific processing

systems(from modular or multiple resource

theory)

Single or Multiple Processors?

Central Executive(central, limited capacity

processor)

Visuo-Spatial Sketchp

ad

Phonological Loop

Modality-specific processing systems

Single or Multiple Processors?

Good compromise?Still got problemsRole of the central executiveHow different components are

integrated

Summary

Divided attention- studied using dual task experiments- influenced by task similarity

task difficulty task practice

Summary

Kahneman- single, limited capacity central

processor- explains effect of task difficulty and

practice- does not explain effect of task

similarity on performance

Summary

Norman and Bobrow- modified version of central capacity

model- tasks: resource-limited

data-limited- more flexible model- problem: non-falsifiable

Summary

Allport- modular approach- different modules with individual resources & capacities- better at explaining influence of task similarity- supported by findings of cognitive neuropsych- problem: does not specify number of modules how modules are integrated

Summary

Navon and Gopher- multiple resource theory- similar to Allport- similar strength and weakness

Summary

Baddeley- synthesis theory- central limited capacity

processor- individual processors for

different tasks

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