Decision Time and Movement Time: Differential Effects of Practice

Abstract

Choice Reaction Time involves at least two components of response latency, Decision Time and Movement Time. Studies usually report values for these two components averaged over a definite number of trials. The aims of this study were to investigate the pattern of behaviour of the two components across the trials and the effect of repeating the experimental procedure two weeks later. 16 control subjects were given two sessions of 50 trials each. In Session 1 (D.0), the two components behave quite differently across the trials; there was no significant change in decision time, but a significant reduction in movement time occurred. Decision and movement time show no relationship. In Session 2 (D.15), a different pattern was found; movement time was still significantly reduced across trials but there was also a significant increase in decision time so the two components exhibit a negative relationship. Comparison of values from Sessions 1 and 2 shows an effect is found only on the first 10 trials for both components, the values of decision and movement times being smaller in Session 2 than Session 1.