The influence of stationary and moving textured backgrounds on smooth-pursuit initiation and steady state pursuit in humans.

We investigated the effects of stationary and moving textured backgrounds on the initiation and steady state of ocular pursuit using horizontally moving targets. We found that the initial eye acceleration was slightly reduced when a stationary textured background was employed, as compared to experiments with a homogeneous background. When a moving textured background was introduced, the initial eye acceleration was significantly larger when the target and the background moved in opposite directions than when the target and the background moved in the same direction. The use of stationary and moving textured backgrounds resulted in comparable effects on the initial eye acceleration when they were presented either as a large field or as a narrow, horizontal small field, only covering the trajectory of the target. Moreover, small-field stationary backgrounds slightly reduced the eye velocity during steady state pursuit. A small-field background moving in the opposite direction to the target distinctly reduced eye velocity, while a target and a background moving in the same direction sometimes even improved pursuit performance, when compared with a homogeneous background. The influences of small-field textured backgrounds on steady state pursuit were comparable with those of large-field backgrounds in both stationary and moving conditions.