Perceiving the self-generated motion on the retina caused by smooth pursuit

Visual perception in humans is intermingled with eye movements. Despite the self-generated motion on the retina by smooth pursuit and saccades, we perceive a stable world, a marvelous achievement by the visual system. We developed a novel stimulus that leads to loss of visual stability across saccades and that is perceived differently if pursued, highlighting the limitations of the visual systems to compensate for eye movements and providing new insight into the underlying mechanisms. The stimulus consisted of a random dot distribution. Across frames, dots in a circular zone rotated to create a vortex motion. Independent of the first-order motion within it, the vortex then moved across the screen. We formerly reported that the vortex cannot be pursued smoothly and that tracking the vortex with frequent catch-up saccades causes a loss of visual stability. Here, we altered the vortex to make it pursuable by dislocating the dots once they became part of the motion pattern and when leaving the vortex, creating a slim ring of flickering and discontinuity around the vortex. Once participants were able to pursue the altered vortex, this also restored visual stability. Interestingly, successful smooth pursuit also changed the perception of the vortex motion pattern. When asked to identify the formerly observed motion pattern in a discrimination task, participants more often chose the pattern with additional first-order motion congruent with the motion pattern’s movement across the screen than the correct pattern. This contrasted sharply with trials involving the unaltered vortex, where participants mostly identified the correct pattern. Consequently, this indicates that motion patterns are perceived based on the retinal image, rather than their actual presentation on the screen, uncovering a novel interaction between smooth pursuit and perception.