Comparing intra- and inter-personal coordination systems: Perceptual effect on stability of finger tapping movement

An experiment was conducted to reveal the differences between intra-personal and inter-personal systems in terms of the perceptual effect on the stability of the finger-tapping movement in the in-phase vs. anti-phase modes. We investigated a between-subjects factor, i.e., the intra-/inter- personal condition, and a within-subject factor, i.e., the phase mode. In the intra-personal condition, ten participants each bimanually tapped their index fingers on a table, in time with a metronome, at a frequency gradually increasing from 1 to 3 Hz over a 30-s trial. In the inter-personal condition, ten pairs of participants were asked to perform the same task as in the intra-personal condition, but to use their right or left index finger, while sitting next to each other and looking at each other's fingers moving. The analysis showed that the average number of phase transitions and average time-to-transition differed between the intra- and inter-personal systems. Some of the results do not agree with the predictions made using the theoretical model proposed in previous studies on inter-limb coordination.