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Performance variability: effects of age and task complexity
Gorus E, De Raedt R & Mets T
Aim and methods.
Performance variability of reaction time (RT) is regarded as an important parameter for cognitive functioning with aging. At least three types can be distinguished, namely diversity, dispersion and inconsistency. While most research on RT and variability focuses on tasks with a large amount of trials, we present a short task with different complexity levels and easy to calculate variability measures, which can be readily introduced in clinical practice. The aim of this study was to assess interactions between age and, inter- and intra-performance variability within a single stratified reaction time test (RTT) with different complexity levels, while differentiating between decision and movement time. Twenty-seven younger and 27 older individuals participated in the study.
Results.
There were consistent age and complexity differences for all variability types in our sample. When controlling for processing speed, which was slower in the older group, variability across age groups and task complexity tended to diminish and a more complex picture emerged. The elderly group showed a higher diversity of all reaction time measures, except for movement time, and a higher dispersion of decision time. Task complexity significantly affected the diversity of movement time and overall reaction time and the dispersion of all reaction time measures, except for movement time.
Conclusions.
Research until now has focused mainly on a theoretical level and few attempts have been made to find relevant parameters for clinical practice. This study argues for a pragmatic approach to examine performance variability, with a relatively easy to use RTT, obtaining valid and possible clinically useful parameters.
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