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Expectancy and response strategy to sensory stimuli
D S Goodin1, M J Aminoff, T A Ortiz
1Department of Neurology, University of California, San Francisco 94143.
Neurology
|October 1, 1993
Summary
This study shows that the brain dynamically adjusts response preparation based on stimulus probability, even when anticipating the wrong stimulus. Accurate and rapid responses to unexpected stimuli suggest integrated stimulus evaluation and response selection processes.
Area of Science:
- Neuroscience
- Cognitive Psychology
Background:
- Reaction-time tasks assess the link between stimulus perception and motor response.
- Anticipatory brain activity, like premovement potentials, reflects response preparation.
Purpose of the Study:
- To investigate the relationship between sensory discrimination and response selection in reaction-time tasks.
- To examine how the brain adjusts response preparation based on stimulus likelihood and occurrence.
Main Methods:
- Subjects performed auditory reaction-time tasks with stimuli of varying occurrence likelihood.
- Cerebral potentials, including premovement potentials and lateralized readiness potentials, were recorded.
- Analysis focused on changes in brain activity following unexpected stimulus occurrences.
Main Results:
- Premovement potentials initially indicated preparation for the most frequent stimulus.
- Brain activity shifted to anticipate the next most likely stimulus after an unexpected tone.
- Subjects responded accurately and rapidly even to the least probable stimulus, despite failed anticipation.
Conclusions:
- Stimulus evaluation and response selection are integrated, dynamic cerebral processes.
- The findings challenge the traditional functional significance attributed to the premovement readiness potential.