Different Stable Patterns between Intra- and Inter-personal Systems: Experimental Study on Inter-limb Tapping Coordination

To reveal the differences between intra- and inter-personal systems in terms of the perceptual effect on the stability of inter-limb coordination, the present study conducted a finger-tapping experiment in in-phase and anti-phase mode. We investigated a between-subjects factor (the intra-/interpersonal condition), and a within-subject factor (the phase mode). In the intra-personal condition, participants bimanually tapped their index fingers, paced by a metronome, with the frequency gradually increasing from 1 Hz to 3 Hz. In the inter-personal condition, pairs of participants were asked to perform the same task, but to use their right or left index finger, while sitting side-by-side and looking at each other’s fingers moving. Analysis showed that the average number of phase transitions, average time-to-transition and standard deviation of the relative phase differed between the intra-personal system and inter-personal system. Some results do not agree with the predictions of theoretical model proposed in previous studies on inter-limb coordination.