Variable Foreperiods and Temporal Discrimination

Abstract

Temporal judgements are often accounted for by a single-clock hypothesis. The output of such a clock is reported to depend on the allocation of attention. In the present series of experiments, the influence of attention on temporal information processing is investigated by systematic variations of the period preceding brief empty intervals to be judged. Two indicators of timing performance, temporal sensitivity, reflecting discrimination performance, and perceived duration served as dependent variables. Foreperiods ranged from 0.3 to 0.6 s in Experiments 1 to 4. When the foreperiod varied randomly from trial to trial, perceived duration was longer with increasing length of foreperiod (Experiments 1 and 3 with brief auditory markers and Experiment 4 with brief visual markers), an effect that disappeared with no trial-to-trial variations (Experiment 2). Longer foreperiods also enhanced performance on temporal discrimination of auditory empty intervals with a base duration of 100 ms (Experiments 1 and 5), whereas discrimination performance was unaffected for auditory intervals with a base duration of 500 ms (Experiment 3). The variable-foreperiod effect on perceived duration also held when foreperiods ranged from 0.6 to 1.5 s (Experiments 57). Findings suggest that foreperiods appear to effectively modulate attention mechanisms necessary for temporal information processing. However, alternative explanations such as assimilation or compatibility effects cannot be totally discarded.

Foreperiod and range effects on time interval categorization

“…Indeed, in the variable FP conditions, BPs decreased monotonically as relative FP length (measured as FP rank) increased. This is consistent with the results from the previous studies on the subject of FP effects on time perception (Gamache et al, 2011;Grondin & Rammsayer, 2003;Mo & George, 1977) and on RT (Niemi & Näätänen, 1981;Requin, Granjon, Durup, & Reynard, 1973). Also, the magnitude of that decrease was significantly larger for the 900-ms FP range conditions than for the 150-ms and 300-ms ones.…”

“…Together, these findings thus bring further credibility to the temporal preparation explanation of the FP effect on time perception (Gamache et al, 2011;Grondin & Rammsayer, 2003;Mo, 1990;Mo & George, 1977). When target time intervals follow randomized FPs, it creates uncertainty regarding the time-of-arrival of the onset of the target interval.…”

“…Looking at the FP effect on time perception from the perspective of temporal preparation, it could be said that the core findings in the literature regarding the variable FP effect mostly pertain to the effect of posterior temporal uncertainty on perceived duration, i.e., on the effect of the relative FP lengths on perceived duration (Gamache et al, 2011;Grondin & Rammsayer, 2003;Mo & George, 1977). Some of these studies did identify factors influencing the FP effect that can be construed as modulators of prior temporal uncertainty.…”

“…As with simple RT experiments following the same variable FP paradigm, the participants' temporal preparation increases as FP elapses. Recent successful replications of the variable FP effect on time perception have attested the robustness of this empirical effect as well as the significance of the temporal preparation explanation (Bendixen, Grimm, & Schröger, 2005;Gamache, Grondin, & Zakay, 2011;Grondin & Rammsayer, 2003;Los & Horoufchin, 2011). This type of manipulation also has been used for studying time-order judgments (Bausenhart, Rolke, & Ulrich, 2008).…”

“…We used the same general experimental design as Grondin and Rammsayer (2003) and Gamache et al (2011), i.e., a task in which participants are asked to judge whether a given temporal interval delimited by two tones is shorter or longer than a 100-ms standard interval. It should be noted that, in this kind of experimental design, the participants' subjective duration of the target intervals is measured by the bisection point (BP).…”