Effects of concurrent verbal rehearsal and temporal set upon judgements of temporal duration

Subjects (N = 252, college students) rehearsed a 30-item free-recall list, or rested for one of three intervals (32, 42 or 54 sec), on the first, third, or ninth study trial. At the conclusion of the interval, subjects made an absolute judgement of interval duration. Half the subjects were informed that this time judgement would be required prior to the interval (prospective), and the remainder were not informed of the required time judgement until after the interval (retrospective). As the number of previous trials increased, judged time (1) increased linearly in the prospective-rehearsal group, (2) decreased linearly in the retrospective-rehearsal group, and (3) had no effect on the nonrehearsal groups. Prospective judgements were greater than retrospective. It was concluded that retrospective time judgements are a function of the amount of information the subject remembers having processed during the interval.