Exploring the relationship between working memory capacity and task switching : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Psychology at Massey University, Manawatū, New Zealand
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Date
2019
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Massey University
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Abstract
Tests of task switching and working memory capacity are both thought to assess
executive attentional control. Given that they are purported to measure the same
underlying cognitive construct, one would expect a relationship between performance
on these tasks. However, preliminary research has largely failed to find such an
association. This thesis explored the association between task switching and working
memory capacity to determine why previous research has failed to find this expected
relationship. Experiment 1 examined this relationship across three commonly used task
switching paradigms which differed in the amount of environmental support available to
participants as they completed the task. Experiment 2 explored the role of task difficulty
on the switching paradigm because working memory capacity and cognitive control are
most related under particularly taxing conditions. Both of these Experiments failed to
find a clear relationship between task switching and working memory capacity. These
findings replicated much of the previous research in this area and suggested that task
difficulty and paradigm choice could not explain the failure of previous research to find
a relationship between these two constructs. Experiment 3 explored the role of cue
switch costs. The task switching paradigm confounds cue switching and task switching,
and it has been argued that switch costs may largely be explained by the cost of the cue
switching. If this is the case, and cue switch costs do not index attentional control, then
it is not surprising that previous research has failed to find a relationship between task
switching and working memory capacity. Experiment 3 found evidence of cue switch
costs, but ‘true’ task switch costs remained. After the confounding effect of cue
switching was controlled for, the expected negative linear relationship between working
memory capacity and task switching was found. Participants with higher working
memory capacity had smaller switch costs, indicative of better performance. The results
of this thesis point to the importance of making careful experimental design decisions
when using the task switching paradigm. This is particularly important when the goal of
such research is to index attentional control, especially in the context of individual
differences research.
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Keywords
Short-term memory, Behavior modification, Attention