Influence of an intertrial interval on sequential effects related to preparatory period duration for reaction time-task.

In reaction time tasks, where the moment of occurrence of the response signal is uncertain, the temporal constraints of preparatory processes imply that subjects distribute their preparation during the preparatory period. The notion of cost of preparation has been proposed to explain the time course of these processes. This experiment was run to determine the effect of the cost of preparation on a serial-RT task and on a RT task where a rest interval of various possible durations (3, 6, or 9 sec.) is introduced. 12 subjects were tested. Data show that the amount spent on preparation during a trial affects the subject's performance during the next trials. But an hypothesis about memory search must also be advanced to explain the effect of the rest interval on the relationship of RT and the current preparatory period.