Modality Differences in Timing: Testing the Pacemaker Speed Explanation

A classic effect in the timing field is that “sounds are judged longer than lights” (Goldstone, Boardman & Lhamon, 1959). Recently, judgements for tactile durations have been found to fall between the two (Jones, Poliakoff & Wells, 2009). These modality differences are commonly interpreted within scalar timing theory as the work of a central pacemaker which runs faster for sounds, then vibrations, and slowest for lights (Wearden, Edwards, Fakhri & Percival, 1998). We investigated whether verbal estimates and temporal difference thresholds are correlated within each modality, but found this not to be the case. This suggests that differences in pacemaker speed may not be the main driver for modality differences in thresholds. In addition, we investigated sensory bias as an alternative to the pacemaker explanation, but this was found not to correlate with modality differences in timing.