4. Dual task experiments
Eysenck & Keane(1995) have identified
three major factors that affect the
ability to do two(or more) tasks at once
Task similarity
Task difficulty
Practice
5. Task similarity
Allport et al.(1972):shadow prose and
learn a list of words(recall)
Present to the other ear(poor)
Print on a screen
Present as pictures on a screen(very
good)
It is a difficult concept to define
7. Practice
Spelke et al.(1976):write down dictated
words while reading short stories
Reasons
1. Reduce the amount of resource
2. Help participants learn strategies
9. Central capacity theory
Kahneman(1973)
Attention as a skill rather than a process
Mental effort=tasks require different
processing capacity
The difficulty of the task & the degree of
practice
10. Central capacity theory
Kahneman(1973) Arousal
central processor
Available
Capacity
Enduring
Dispositions
Allocation
Policy
Momentary
Intentions
Evaluation
Possible Responses
of Demands
on Capacity
Response
11. Evaluation
Task difficulty, the role of practice and
arousal
Problems
1. The limits of capacity
2. Does not explain the strong influence of
similarity
14. Multiple channel theories
A limited capacity model
A central processor A single filter
Explaining the complex Dealing with all
nature of attention (Neisser, attentional tasks?
1976 ; Allport, 1993) ?
Dealing with many different types of task
required by an attentional system ?
•It is difficult to see how the neurology of the brain could
produce a system of processing a capacity
(Hampson and Morris,1996)
15. 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
16. (1)Listening to (2)List of words
a massage to be learned
(3)Shadowing
message
(1)Listening to
a massage
(1)List of pictures
(3)Shadowing to be learned
message
17. Evaluation of module theory
To explain the effects of similarity in dual task
experiments
(Allport et al.,1972
Treisman and Davies, 1973)
18. 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
19. Evaluation of module theory
Problem 1 Problem 2
It doesn’t specify the How the modules work
number of modules together?
What types of modules How the modules are
they are? co-ordinated
The theory is therefore Enough practice
non-falsifiable The similar tasks can
work concurrently
Competing for the
resources of one module
(Underwood, 1974;
Spelke et al., 1976)
20. 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)
23. 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
24. 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
25. Multiple Resource Theory
Failure to specify number of resources
How the multiple resources work together
Attentional processes highly integrated
HOW?
26. 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
27. 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)
28. Single or Multiple Processors?
Central Executive
(central, limited capacity
processor)
Modality-specific
processing systems
Visuo-
Spatial Phonological Loop
Sketchpad
29. Single or Multiple Processors?
Good compromise?
Still got problems
Role of the central executive
How different components are integrated
30. Summary
Divided attention
- studied using dual task experiments
- influenced by task similarity
task difficulty
task practice
31. Summary
Kahneman
- single, limited capacity central processor
- explains effect of task difficulty and practice
- does not explain effect of task similarity on
performance
32. Summary
Norman and Bobrow
- modified version of central capacity model
- tasks: resource-limited
data-limited
- more flexible model
- problem: non-falsifiable
33. 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
34. Summary
Navon and Gopher
- multiple resource theory
- similar to Allport
- similar strength and weakness
35. Summary
Baddeley
- synthesis theory
- central limited capacity processor
- individual processors for different tasks
