Classification of responses to metronome phase shift during synchronized stepping

Kevin Lucas, Hui-Ya Chen & Alan M Wing

University of Birmingham, UK

In finger tapping studies metronome phase shift induces a rapid adjustment of response timing that is often considered to be well described by a first order linear phase correction. We were interested to see whether this would also be true of stepping and what might be the effects of dance skill. We will describe the response to metronome phase shift in a study that involved 20 participants, 10 dancers with at least 13 years of training and 10 non-dancers who were instructed to step in time to a metronome set at 500 ms. Stepping movements were recorded with an Oxford Metrics Vicon system running at 120 Hz in order to determine the times of toe contact relative to metronome onset. On each trial the metronome phase was shifted forward or back by 125 or 250 ms in separate blocks at an unpredictable point. The instructions were either to continue in the old phase (IGNORE) or to change to the new phase (ADJUST). Compensation functions, with asynchrony rapidly reducing after phase shift, were more often seen in the ADJUST condition although they were also frequently observed in the IGNORE condition. A number of other response to the phase shift were seen which depart from the predictions of the first order linear phase correction model and these will be detailed in the poster.