Attentional influences on the performance of secondary physical tasks during posture control.

We examined the influence of attentional focus and cognitive load on motor performance in a dynamic stick balancing task during the maintenance of upright posture. Dynamical analyses of postural fluctuations revealed the existence of a drift and correct mechanism, with correlational structure reflecting the demands of the stick balancing task. In contrast, experimentally manipulated attentional foci (internal, external) did not influence the variability of postural or fingertip trajectories. However, dual-task cognitive stick balancing performance resulted in decreased variability of postural and fingertip time series. These results are discussed in the context of dual timescale models for posture control and stick balancing.