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.