Impact of simulated low target vision on target-directed movement


Investigations of visually-guided aiming typically compare closed-loop (full vision) and open-loop (no vision) conditions combined with variations in temporal and spatial parameters. However, it remains to be fully determined how individuals respond to situations of poorer vision (i.e., low spatial frequency). In Experiment 1, participants executed a fast-and-accurate aim to a target on a dark background in conditions of high (bandwidth) and low (sinusoidal) spatial frequency, as well as high (white) and low (grey) luminance contrast. Despite differences in the perceived size of the target, as indicated by pre-experimental target size adjustments, there were no significant effects of spatial frequency and luminance on temporal and spatial measures. However, there was a significant increase in reaction time (RT) when presented with low compared to high spatial frequency targets. Consequently, Experiment 2 examined the attentional/processing demand of aiming with low spatial frequency information by incorporating a secondary auditory probe during the RT interval. Contrary to Experiment 1, there was no significant effect of spatial frequency on movement RT. However, there was a significantly longer time after peak velocity when presented with a low spatial frequency target, which coincided with lower radial error. Additionally, there was no effect of spatial frequency on probe RT. Presumably, the change in preparatory and movement effects was an attempt to avoid interference imposed by the initial probe stimulus. These findings reflect the continued advantage served by degraded visual information, and how performers compensate for this in pre-movement planning, or if necessary, online visuomotor control.