Judging object velocity during smooth pursuit eye movements

Abstract

Our tendency to constantly shift our gaze and to pursue moving objects with our eyes introduces obvious problems for judging objects' velocities. The present study examines how we deal with these problems. Specifically, we examined when information on rotations (such as eye movements) is obtained from retinal, and when from extra-retinal sources. Subjects were presented with a target moving across a textured background. Moving the background allowed us to manipulate the retinal information on rotation independently of the extra-retinal information. The subjects were instructed to pursue the target with their eyes. At some time during the presentation the target's velocity could change. We determined how various factors influence a subject's perception of such changes in velocity. Under more or less natural conditions, there was no change in perceived target velocity as long as the relative motion between target and background was maintained. However, experiments using conditions that are less likely to occur outside the laboratory reveal how extra-retinal signals are involved in velocity judgements.

Contrast and Assimilation in Motion Perception and Smooth Pursuit Eye Movements

“…Data points falling in between the boundaries are considered as unclassified, which means that responses are well predicted by both models because correlation coefficients do not significantly differ from each other. movement signals (Brenner and Van den Berg 1994;Souman et al 2005). If the perceptual judgments obtained here were due to a compensation for pursuit velocity, the pursuit response should differ between judgment categories and be higher for "slower" judgments than for "faster" judgments.…”

How Position, Velocity, and Temporal Information Combine in the Prospective Control of Catching: Data and Model

“…To assess the validity of the added velocity information stream, this information must be perturbed experimentally. Background visual field motion (VFM) has been shown to affect the perceived velocity of a target moving across a background (e.g., Schweigart, Mergner, & Barnes, 2003;Smeets & Brenner, 1995;Brenner & Van den Berg, 1994;Brenner, 1991) and to influence hand movements in a number of tasks, including hitting (Smeets & Brenner, 1995), manual tracking (Masson, Proteau, & Mestre, 1995), and predictive pointing (Soechting, Engel, & Flanders, 2001). In accordance with these observations, Dessing et al (2002) predicted an effect of VFM on the TVV and examined its effect on the planned hand trajectories generated by the RRVITE model.…”

Goal-Directed and Goal-Less Imitation in Autism Spectrum Disorder

“…Reduced visual sensitivity during saccades (Burr et al 1994) would reduce the amount of visual information gained by the ASD group, which would impair reflection of speed changes. In contrast, the control group optimised the amount of information they received about the movement by making pursuit movements in the notarget clips; the increased extra-retinal input guiding eye velocity (Brenner and Berg 1994), and improved visual sensitivity during pursuit (Schutz et al 2008) may have contributed to the success of the control group in modulating their movements. Nevertheless, we found that the ASD participants did increase the amount of pursuit they performed in the goal-less compared to goal-directed condition, despite failing to modulate their movements.…”