Negative errors in time reproduction tasks.

In time reproduction tasks, the reaction time of motor responses is intrinsically linked to the measure of perceptual timing. Decisions are based on a continuous comparison between elapsed time and a memory trace of the to-be-reproduced interval. Here, we investigate the possibility that negative reproduction errors can be explained by the tendency to prefer earlier over later response times, or whether the whole range of possible response times is shifted. In experiment 1, we directly compared point reproduction (participants indicate the exact time point of equality) and range reproduction (participants bracket an interval containing this time point). In experiment 2, participants indicated, in three separate tasks, the exact time point at which the reproduction phase was equal to the standard duration (point reproduction), the earliest (start reproduction), or the latest moment (stop reproduction) at which the exact time point of equality might have been reached. The results demonstrate that the bias towards earlier responses not only affects reproduction of the exact time point of equality. Rather, even if the decision threshold is changed in favor of late responses, they exhibit a continuous shift towards negative errors that increases with the length of the standard duration. The findings are discussed in the context of the hypothesis that systematic errors in time reproduction tasks reflect a dimension-unspecific tendency towards earlier responses caused by the psychophysical method rather than by a time-specific perceptual distortion.