[Decision strategy as a function of event probability: 2. Latency of the decision and covering the field]

A fair number of studies have been conducted in order to assess the effect of event probability on decision strategy in a two choice reaction time (CRT) task. Results showed that increasing the probability of an event from 0.5 to 0.8 did not affect CRT. In fact, a significant decrease in CRT was obtained only when one of the two stimuli reached a probability of 0.9. It was concluded from these studies that subjects used a very conservative decision strategy. It should be pointed out that in these studies the instructions given to subjects emphasized both speed and accuracy of response. In many sport situations however, a player must choose speed of response over accuracy. For example the tennis player who knows that the opponent will smash the ball either to his right or hs left. The purpose of the present study was to determine whether or not in such situations the defensive player might not choose a less conservative decision strategy than that presented earlier. Fourteen subjects were submitted to a two CRT task, where the probability of each event and the time allotted (TA) to complete the appropriate response were systematically manipulated. The results obtained for each level of TA were similar to those discussed earlier. More specifically, a significant decrease in CRT was obtained only when one of the two possible events reaches a probability of 0.9. However, it appeared that, reducing TA forced subjects to reduce CRT and to base their responses more and more on anticipation than on reaction.