Benefits and limits of explicit counting for discriminating temporal intervals.

Segmenting information into smaller parts helps to process it, and this is also true for temporal information. The aim of the present article is to compare the benefits of using explicit counting in a temporal discrimination task under various marker-type conditions and to show the limits of this strategy. In Experiment 1, conditions with and without counting were compared for two implicit standard durations, .8 and 1.6 s, in connection with three marker-type conditions, which were intervals marked by: 1) two brief auditory signals (Auditory-Auditory); 2) two brief visual signals (Visual-Visual); and 3) one auditory signal followed by a visual signal (Auditory-Visual). At .8 s, marker-type differences are significant (best in audition, worse with a bimodal sequence), and remain present with an explicit counting strategy. At 1.6 s, explicit counting provides clear improvements of performance in all marker-type conditions and annihilates marker-related differences. Experiment 1 also suggests that standard deviation remains constant from .8 to 1.6 s in the counting condition, while Experiment 2 shows that when standard intervals are extended up to 4 s, explicit counting does not totally prevent variance from increasing as base duration becomes progressively longer. The benefits derived from using explicit counting in duration discrimination are argued to depend (1) on a reduction of variance in the memory process involved in the timing mechanism, and (2) on a change in the decisional process.