Abstract
An important but often neglected aspect of locomotor interception is knowing which targets to chase and which to let go. Sometimes targets are moving too quickly to catch; others are catchable but only by sprinting, leaving oneself with temporarily diminished capabilities for pursuing future targets. The aim of this study was to investigate whether humans are perceptually attuned to the immediate and longer-term effects of fatigue on their ability to catch targets. On each trial, a target in a desktop virtual environment moved through a field and had to be caught before it reached a forest. Subjects were instructed to catch as many targets as possible in blocks lasting five minutes each. Fatigue was simulated by cumulatively decreasing the gain on the speed controller when it was maximally displaced. Subjects could also recover by resting, but the block timer continued to count down as they did so. In the Carryover condition, energy level carried over from one trial to the next, so subjects had to decide whether pursuing a target on one trial was worth the diminished ability to pursue the next target. Performance was compared to that in a No Carryover condition in which energy level was reset on each trial. Subjects refrained from pursuing catchable targets more often in the Carryover condition, revealing sensitivity to the influence of fatigue on their ability to catch future targets. There was also a third, Fixed Energy condition in which energy level remained constant throughout the entire block. Interestingly, behavior in No Carryover and Fixed Energy conditions was similar, suggesting that subjects were relatively insensitive to the effects of fatigue on the catchability of the current target. We consider the implications for the affordance-based control of locomotor interception, particularly for tasks that involve repeatedly intercepting moving targets.
Acknowledgement: ONR N00014-18-1-2283