Does an auditory distractor sequence affect self-paced tapping?

Bruno H. Repp

Haskins Laboratories, USA

This study investigated whether an auditory distractor (D) sequence necessarily affects the timing of self-paced finger tapping. Experiment 1 was conducted to replicate earlier findings (Repp, 2003) showing that, when taps are synchronized with an isochronous auditory target (T) sequence, an isochronous D sequence of different tempo and pitch systematically modulates the tap timing without participantsí awareness. Experiment 1 showed in addition that the extent of the modulation depends on the relative intensity of the T and D tones, but not on the pitch distance between the T and D tones. In Experiment 2, a synchronization-continuation paradigm was used in which D sequences of different tempo and pitch were introduced only during continuation tapping. The results show that, although the D sequences rarely captured the taps completely, they did increase tapping variability and deviations from the correct tempo. More interestingly, they also eliminated the negative correlation between successive inter-tap intervals (the lag-1 autocorrelation) that is characteristic of self-paced tapping. Furthermore, an analysis of the distribution of the asynchronies between taps and D tones revealed that intermittent phase locking occurred when the tapping period was close to the period of the D sequence, with phase leads or lags depending on the difference between the two periods. These distractor effects occurred regardless of whether or not the taps were made to generate an auditory feedback tone, and they again seemed to occur without participantsí awareness. The results suggest that auditory distractor effects depend neither on the intention to synchronize with a T sequence nor on the simultaneous perception of a T and a D sequence. Rather, they seem to reflect a basic attraction of rhythmic movement to auditory rhythmic stimulation.