Response to period shifts in tapping and circle drawing: a window into event and emergent components of continuous movement.

Synchronization of movement to a metronome is a well-studied task for both discretely and smoothly produced rhythmic movement. In particular, behavioral responses to unexpected changes in a regular metronome can reveal both the strength and the completeness of error correction mechanisms and temporal control. Clock-like control is exhibited by discretely produced movement and movement with discrete perceptual information, whereas smoothly produced movement does not rely on internal clock mechanisms. Documented differences in error correction between discretely and smoothly produced movements have been attributed to this different underlying control. In this study, error correction mechanisms were examined by inducing changes in the pace of rhythmic movement. An overshoot response following the pace change for both tapping and circle drawing is documented, and suggests the presence of phase and period correction in both tasks. The presence of phase correction in circle drawing also suggests that clock and non-clock timing may co-exist within the same movement. Furthermore, a sub-group of participants emerged who appropriately changed pace, but were not able to correct the phasing of their movement while performing the circle drawing task, supporting that phase and period maintenance in timing are independently controlled processes.