Predictive smooth pursuit eye movements during identification of moving acuity targets

Repetitive, brief target ramp movements every few seconds lead to anticipat ory acceleration before each ramp onset and anticipatory deceleration befor e ramp offset. We assessed whether identifying novel changes in the pursuit target would alter this pattern of anticipatory pursuit. Without target id entification (TI), anticipatory acceleration increased when intervals betwe en ramps were regular, rather than random. It increased further when, betwe en ramps, the target was invisible rather than stationary and visible. Anti cipatory deceleration increased when the target was expected to stop rather than disappear at ramp offset. For TI trials, the pursuit target changed b riefly into a Landolt C acuity target that had to be identified. Compared t o no TI, anticipatory acceleration decreased when a stationary C always app eared just before ramp onset. It increased when a moving C appeared just af ter ramp onset, but only when the target was invisible between ramps. Antic ipatory deceleration was reduced when a moving C appeared just before ramp offset, but did not increase when a stationary C appeared just after ramp o ffset. The changes were significant, but of small magnitude, suggesting tha t predictive pursuit, especially with a visible target between ramps, canno t be greatly influenced by attempts to selectively improve acuity at a part icular phase of the stimulus. (C) 1999 Elsevier Science Ltd. All rights res erved.