Effects of attentional strategies and anxiety constraints on perceptual-motor organisation of rhythmical arm movements.

Effects of anxiety on perceptual-motor organisation of rhythmical forearm movements were examined using an interrupted time series design with staggered baselines. Participants were exposed to repeated baseline sessions interrupted with two anxiety-inducing sessions. Results showed that under moderate levels of anxiety, determined from CSAI-2 and heart rate data, phase relations between oscillating forearms became more stable in in-phase (0 degrees ) and anti-phase (180 degrees ) modes, although these patterns were not maintained in baseline sessions following the anxiety manipulation. Data were consistent with participants employing a strategy of allocating greater attentional effort in stabilizing preferred co-ordination patterns under anxiety-inducing conditions. Results suggest that anxiety can temporarily act as a source of behavioural information, leading to the re-parameterisation of participants' intrinsic dynamics.

Local stability in coordinated rhythmic movements: fluctuations and relaxation times.

An experiment was conducted to examine the stability of the anti-phase and in-phase modes of coordination by means of both fluctuations and relaxation times. Participants (n=6) performed a rhythmic bimanual forearm coordination task that required them to oscillate their forearms in-phase and anti-phase while grasping two manipulanda at fixed frequencies ranging from 0.6 to 1.8 Hz. Relaxation times were measured as the time taken to return to a stable mode following the application of a transient mechanical torque. It was found that relaxation times were not different statistically across participants, frequencies, and coordinative modes. However, fluctuations, as indicated by the mean S.D. of relative phase across individual frequency plateaus, were significantly greater in the anti-phase than in the in-phase mode of coordination, p<0.05. Whilst providing new empirical support for the notion that relaxation times should be of the same order of magnitude at frequencies outside transition regions, the findings suggest that the level of stochastic noise in the anti-phase mode is greater than that of the in-phase mode. Implications are made for the future assessment of local pattern stability.