Multiple timing of nested intervals: Further evidence for a weighted sum of segments account.

How people perceive temporally overlapping intervals can inform us about the architecture and constraints of the human timing system. In the present study, we examined the time perception of two overlapping intervals in a nested context. In this context, one short interval (1 s) was temporally nested within another long interval (3 s). The data showed that although participants' perception of the short interval was unaffected by its temporal position within the long interval, estimates of the long interval decreased, the later the short interval appeared. These data indicate that participants perceive two overlapping intervals as three segments that must be summed in order to estimate the long interval. Importantly, the temporal relationships between overlapping intervals affect the estimates, because a recency weighting is applied to each segment during the summing process. Within pacemaker-accumulator models, these results could be seen as supporting a timing system composed of a single pacemaker and a single accumulator, but they could also constrain any account of human interval timing.