| Abstract | When tapping is paced by an auditory sequence containing
small phase shift (PS) perturbations, the phase correction
response (PCR) of the tap following a PS increases with the baseline
interonset interval (IOI), leading eventually to overcorrection
(B. H. Repp, 2008). Experiment 1 shows that this holds even for
fixed-size PSs that become imperceptible as the IOI increases (here,
from 400 to 1200 ms). Earlier research has also shown (but only for
IOI = 500 ms) that the PCR is proportionally smaller for large than
for small PSs (B. H. Repp, 2002a, 2002b). Experiment 2 introduced
large PSs and found smaller PCRs than in Experiment 1, at all of
the same IOIs. In Experiments 3A and 3B, the author investigated
whether the change in slope of the sigmoid function relating PCR
and PS magnitudes occurs at a fixed absolute or relative PS magnitude
across different IOIs (600, 1000, 1400 ms). The results suggest
no clear answer; the exact shape of the function may depend on the
range of PSs used in an experiment. Experiment 4 examined the
PCR in the IOI range from 1000 to 2000 ms and found overcorrection
throughout, but with the PCR increasing much more gradually
than in Experiment 1. These results provide important new information
about the phase correction process and pose challenges for
models of sensorimotor synchronization, which presently cannot
explain nonlinear PCR functions and overcorrection. |