Assimilation between two neighboring time intervals marked with tactile stimuli
The aim of this study was to examine whether and how the perception of an empty time interval marked by two brief tactile stimuli, S, is influenced by the duration of the preceding time interval, P. In each trial, three electric pulses, each lasting 20 ms, were successively delivered to the right hand of participants, the first two pulses marking P and the last two marking S. S was fixed at 240 ms while P was 160, 240, or 320 ms. In addition, there was a control condition where S was presented in isolation (without P). Perceived duration of S was estimated with the method of constant stimuli. Results showed that participants underestimated S when P was 160 ms. This underestimation appeared as a kind of perceptual assimilation between P and S, but indeed S was not overestimated when it was preceded by a longer interval (P = 320 ms). The underestimation was rather regarded as the time-shrinking illusion which had been tested with visual and auditory stimuli.