Abstract
People with amblyopia present deficit in spatial vision such as low acuity and bad contrast sensitivity, but also in motion perception such as inaccurate estimation of speed. In this study, we wanted to test motion trajectory estimation in amblyopic participants. We used a motion prediction task. Participants needed to estimate the time at which a target would reach a designated goal, after its motion had been occluded. The stimuli presented was a white bar moving at a constant speed (2.5, 5, 10, 15 deg/s) for a fixed viewing distance (3, 6, 9 deg) before being occluded for the rest of its trajectory (1, 2, 4, 8 deg). The participants’ task was to press a button when they thought that the occluded target reached the designated goal. We tested three different visual conditions: monocular (amblyopic or fellow eye) and binocular. At medium speeds (5 and 10 deg/s), participants estimated correctly the time-to-reach of the target. However, they overestimated the distance when the speed was high (15 deg/s) and an underestimated it when the speed was low (2.5 deg/s). As occlusion distance was increased, at 15 deg/s, they were performing better. However, at 2.5 deg/s speed, the opposite pattern was observed: increasing the occlusion distance led to worse performance. No difference was observed between the monocular and binocular viewing conditions. Speed seems to be a critical parameter for the ability of amblyopic people to accurately estimate trajectories. Occlusion distance had variable impact on performance at lowest and highest speeds.