Nested task constraints shape continuous perception-action coupling control during human locomotor pointing.

Behavioural studies of human locomotor pointing have been dominated by specific task constraints of generating maximal approach velocity towards spatial targets. To examine locomotor pointing under different nested task constraints, at sub-maximal approach velocities and with concomitant differences in speed-accuracy trade offs, run-ups of professional cricket bowlers (n = 6) were analysed. Inter- and intra-trial analyses of step length adjustments revealed how differences between current and required locomotor pointing behaviour constrained visual adaptations of gait. Results supported a continuous perception-action coupling control mechanism, although no relationship was observed between step number in sequence and total amount of adjustment made, implying that visual adaptations did not continue to the end of a run-up once initiated. Rather, bowlers made step adjustments throughout the run-up, with strong associations for amount of adjustment made and amount needed. Significant variations were observed in inter-individual strategies for making most adjustments at different points of the run-up. A key premise of prospective control models of locomotor pointing was found to be robust, since regulation of cricketer's gait was continuous and based on perception of current and required behaviour. Findings extend understanding of the nature and range of nested task constraints under which perception-action coupling controls locomotor pointing performance.