Relation between probability of preferential choice and time to choose changes with practice

Two experiments with 18 adult male Ss examined relations between 2 response measures, response time and response probability, obtained in a pair-comparison preferential choice task. In each case, the time to make initial choices decreased monotonically as overall response probability increased. This monotone decreasing relation occurred throughout the experiment for choices among lottery gamble stimuli, which were a priori personally important to Ss, but the latency-probability relations became nonmonotonic with practice for less important choices concerning opinions or the aesthetic appeal of geometric forms. These changes in the empirical relation between response time and response probability are incompatible with the predictions of existing choice decision time models, but a psychologically meaningful modification of D. LaBerge's (1962) recruitment model can admit the changes. In addition to the implications for choice decision time models, these empirical latency-probability relations encourage temporal analyses of probabilistic stimulus representations and suggest that knowledge of initial choice response times may greatly aid in the prediction of future choice behavior. (21 ref)