Time Dilation Caused by Oddball Serial Position and Pitch Deviancy

When a deviant stimulus is presented within a stream of homogeneous stimuli, its duration tends to be overestimated. Two experiments investigated the effects of oddball serial position and pitch deviancy on perceived duration. In Experiment 1, the oddball method was used, in which an oddball stimulus is embedded in a series of standard stimuli and randomly positioned in each trial. In Experiment 2, the oddball position was stable and its deviancy varied from trial to trial. Musician and nonmusician participants were asked to judge whether the comparison interval was shorter or longer than the standards. The study indicates that for nonmusicians, the duration of an oddball stimulus appears longer than the repeated standard stimuli. Moreover, the oddballs occurring in later positions in the stream of stimuli are perceived to be longer than oddballs occurring in earlier positions in the stream. Also, a higher degree of oddball deviancy results in a greater dilation of perceived duration. In contrast with the results of nonmusicians, there is neither a position nor a deviancy effect with musician participants; the subjective duration remains constant. Several explanations are discussed in order to account for these group differences.