Abstract
If we want to successfully intercept a moving target, we need an accurate and precise estimate of the velocity at which it moves. Although we normally look at targets that we want to intercept, it is still unclear whether pursuing targets with one's eyes leads to better judgements about how fast they are moving. Judgments might depend on what the eyes are doing, because when pursuing the target with one's eyes, one judges the target's motion from signals related to the movements of the eyes, rather than relying on the retinal slip of the target's image. Previous studies have shown that pursuing a moving target with one's eyes can influence how fast it appears to move, but none have examined how doing so influences the precision with which its velocity can be judged. Here we use a two alternative forced choice discrimination task in which subjects had to judge which of two sequentially presented moving bars moved faster. Each presentation consisted of a static bar at the centre of the screen and a moving bar that moved through the static bar as it moved from left to right across the screen. In different sessions subjects had to either fixate the static bar or pursue the moving bars. One of the two sequentially presented moving bars moved at 5, 10 or 20°/s. The other moved either 10, 30 or 50% slower or faster. We fit psychometric curves to the responses to estimate the precision with which the velocity was judged. Subjects judged the velocity of the moving bars about 10% more precisely when they were pursuing the moving bars with their eyes.
Meeting abstract presented at VSS 2018