The dual influence of pacer continuity and pacer pattern for visuomotor synchronisation

There is growing evidence that movement synchronisation to an external rhythm is affected by the type of pacers involved. Specifically, visuomotor synchronisation (VMS) is facilitated when the pacer is continuous (continuity condition) and moves in the same direction as the movement produced (pattern matching condition). However, the extent to which the continuity and pattern matching conditions each contribute to facilitation of VMS remains unclear. The present study aimed to disentangle the potential dual influence of pacer continuity and pacer pattern on VMS. Twenty participants were asked to synchronise continuous left-right forearm movements of tracking (continuous VMS" Experiment 1) or discrete up-down finger movements of tapping (discontinuous VMS" Experiment 2) with four visual pacers. The pacers consisted of a red dot target that either oscillated (continuous pacers) or flashed (discrete pacers) periodically. The target also exhibited a left-right (left-right pacers) or a centred (centred pacers) movement pattern. Results showed lower variability in synchrony with the continuous visual pacer that respectively matched the left-right and the centred movement pattern of forearm and finger tapping. Both the continuity condition and the pattern matching condition facilitated VMS when synchronising continuous forearm tracking movements (Experiment 1) whereas both conditions were required to facilitate VMS when synchronising discrete finger tapping movements (Experiment 2). These results provide new insights into the mechanisms underlying VMS and how they are modulated by variations in pacer pattern and pacer continuity.