The focus of the present work is the timing pattern of perceptual change elicited by multiple repetitions of a syllable (the verbal transformation effect; Warren and Gregory, 1958). It is shown that the distribution of the dwell time, the time spent perceiving a given phonemic form before switching to another form, obeys a power law with an exponent valued between 1 and 2. This result is robust, occurring for meaningless syllables and for English words of different initial phonemic salience, and for presentations as short as 1000 syllable repetitions or as long as 10 000 repetitions. Thus within this paradigm there is no characteristic time scale for perceptual change. [Work supported by NIDCD Grant No. 5-R29-DC00411, NIMH Grant No. 5-R01-MH42900, and BRSG Grant No. NSS 1-SO7-RR07258.]