A NEW ILLUSION OF TIME PERCEPTION .2.

When one very short empty time interval follows right after another, t he second one can be underestimated considerably, but only if it is lo nger than the first one. We coined the term ''time-shrinking'' for thi s illusory phenomenon in our previous studies. Although we could relat e our finding to some studies of rhythm perception, we were not able t o explain the illusion. The present article presents our attempt to un derstand the mechanism that causes the time-shrinking. Four experiment s are reported. The first one ruled out the possibility that the illus ion results from a difficulty in resolving the temporal structure. The second experiment showed that the listener was not inadvertently judg ing the duration of the first interval instead of that of the second o ne. In addition, this experiment yielded more information about the ti me window within which the illusion occurs. The third experiment showe d that forward masking of the sound markers, delimiting the empty dura tions, could not explain the illusion either. Furthermore, this experi ment revealed a clue to the mechanism of time-shrinking: competition b etween expected and observed temporal positions. The fourth experiment further examined the temporal conditions that give rise to the illusi on and showed that categorical perception plays a crucial role in the formation of the illusion. In the general discussion, we argue that th e illusion is due to an asymmetric process of temporal assimilation.