Sequential Effects of Foreperiod Duration as a function of the Frequency of Foreperiod Repetitions

An examination of sequential effects of foreperiod duration in reaction time tasks suggests a description of the subjects' strategy in terms of a tendency to expect foreperiod repetitions. The present experiment examined what factors influence this basic tendency. Two foreperiod distributions differing in the frequency of repetitions (33 and 66%) but with the same frequency of individual foreperiods were used. In both cases faster reaction times coincided with foreperiod repetitions. Important differences appeared nevertheless between the two foreperiod distributions; reaction times for repetitions were faster when repetitions were frequent than when they were not, and repetitions of the same fore-period more than once led to further reaction-time decreases only when foreperiod repetitions were frequent. The tendency to expect repetitions varied from trial to trial in a way which depended on long-term factors such as the frequency with which the expected foreperiod duration coincided with the foreperiod actually presented.