Attentional demands associated with obstacle crossing while carrying a load.

The extent to which different locomotor tasks require cognitive control is not well characterized. In this article, the authors consider the potential increase in attentional demands associated with carrying an anterior load while clearing an obstacle. Nine healthy male volunteers participated in 80 walking trials, 20 in each of 4 conditions: 1 no load condition (NL) and 3 carrying conditions (2KG, 5KG, and 10KG). Of the 20 trials in each condition, 12 included a probe reaction time (PRT) test during lead limb obstacle crossing, which was used to measure cognitive load. A load-dependent increase in PRT was observed, with PRT in the 2KG condition being significantly greater than in the NL condition, and PRT in the 5KG and 10KG conditions being significantly greater than in the 2KG condition. These results suggested that cognitive load was increased when: (a) the obstacle was occluded from vision by the load, and (b) the magnitude of load was increased.