Visual motion signals are employed to generate oculomotor responses and drive motion perception. A primary concern was whether perceptual and oculomotor motion signal processing had the same mechanism. For a study, researchers used visual motion priming to answer this issue, which involved biasing the perceived direction of a directionally ambiguous stimulus in the same (positive priming) or opposite (negative priming) direction as that of a priming stimulus.
The length of the priming stimulus influences the priming effect. It was hypothesized that high- and low-level motion systems, respectively, promoted positive and negative priming. During different periods, participants were asked to judge the apparent direction of a π-phase-shifted test grating following a smoothly drifting priming grating. Their eye movements were recorded when the test grating was shown to them. When an interstimulus period was added between the priming and test stimuli, the perception and eye movements were discordant under positive priming and correlated under negative priming on a trial-by-trial basis, demonstrating that the test stimulus per se induced the eye movements. The findings implied that at a low level of motion processing, perceptual and oculomotor responses are produced by the same mechanism, but at a high degree of motion processing, they were caused by different processes.