Temporal properties of attention sharing consequent to disturbed balance

THE time course and extent of attentional shifts associated with compensato ry balancing reactions were explored using a novel dual-task paradigm. Seat ed subjects performed a continuous visuomotor tracking task with the hand w hile the feet simultaneously balanced an inverted pendulum. The pendulum wa s randomly-perturbed, evoking compensatory balance reactions. Changes in tr acking performance were held to reflect attentional shifts. Discrete deviat ion in visuo motor,tracking, typically a pause in tracking, began on averag e 235 ms after the onset of the balance reaction (TA EMG; average latency 9 0 ms). Such pauses lasted on-average 600 ms, although additional errors in tracking lasted up to 9s following the perturbation. The findings reveal ev idence of dynamic shifts in attention associated with distinct phases of co mpensatory balance control. The initial phase appears to be triggered autom atically, whereas later phases involve varying degrees of attentional resou rces. (C) 1999 Lippincott Williams & Wilkins.