Attention demands of walking were determined in six male and six female young adults (mean 26.3 yr) and 12 gender-matched healthy, active older adults (mean 71.1 yr) using a dual task procedure with a reaction time (RT) secondary task. In three conditions an auditory stimulus, a visual stimulus and both stimuli (auditory/visual) were presented. Relative to no-walking baselines, increased RT was found in all conditions revealing an attentional cost of normal walking. When participants traversed the laboratory walkway and also positioned one of their feet within a target area on the ground, attention demands were greater than in unconstrained walking. In the targeting task, RTs to the visual stimulus were longer than for the auditory stimulus due to the interference associated with viewing both the stimulus monitor and the foot-target. Older participants' RTs in the visual and auditory/visual conditions, but not in the auditory condition, were significantly longer than for the young group in both walking tasks but RTs for young and older adults were not different in no-walking baseline trials. Inspection of mean RT functions at time intervals following gait initiation (0-3000 ms from the first step) suggested a fluctuating attentional cost of walking with increased demands associated with contingencies requiring step length regulation. The findings have applied significance in demonstrating the possibility of increased falls and pedestrian accident risk in older individuals in dual task situations such as road crossing.
Copyright 2002 Elsevier Science B.V.