SENSORIMOTOR SYNCHRONIZATION - MOTOR-RESPONSES TO PSEUDOREGULAR AUDITORY PATTERNS

Musically trained and untrained subjects (N = 30) were asked to synchr onize their finger tapping with stimuli in auditory patterns. Each pat tern comprised six successive tonal stimuli of the same duration, the first of which was accented by a different frequency. The duration of interstimulus onset intervals (ISIs) gradually increased or decreased in constant steps toward the end of the patterns. Four values of such steps were used in different trials: 20, 30, 45, and 60 msec. Various time-control mechanisms are hypothesized as being simultaneously respo nsible for subjects' incorrect reproduction of the internal temporal r atios of the stimulus patterns. The mechanism of assimilation (of a ce ntral tendency) led subjects to enforce a regular (isochronous) struct ure on the patterns. The influence of other time-control mechanisms (d istinction, subjective expression of an accent, sequential transfer) w as expressed mainly in differences between inter-tap onset intervals ( ITIs) and the corresponding ISIs at the beginning of the patterns. The duration of the first two ITIs was in the majority of the trials in a n inverse ratio to the ratio of the respective ISIs. The distortions r esulting from the timing mechanisms concerned were more pronounced in the performance of nonmusicians than in that of musicians.