We have a new paper just published in the Journal of Neurophysiology. In it, we explored how the perception of very brief flashes is influenced by saccadic eye movements. When we look at rapidly flickering LED lights (e.g. the brake lights of some cars), we often experience these lights conspicuously jumping around back and forth. This is because there is an interaction between our own rapid eye movements while looking around, and when a single flicker of the repetitive lights happens to impinge on our retina. In the lab, this phenomenon is studied by flashing a very brief visual stimulus at strategic times around saccade onset. Depending on the location and time of the flash, observers mislocalize it in highly predictable ways.
In our current study, we were particularly interested in asking whether the strength of perisaccadic perceptual mislocalization depends on the visual appearance of the saccade target. That is, would the same mislocalization happen if we were making an eye movement towards a coarse or a fine pattern? If so, then this would indicate that the mislocalization is independent of the visual context, and only reflects the properties of the shifts of the retinal image caused by saccades. On the other hand, if the mislocalization strength changes for the different visual contexts, then it might suggest that the processes of perisaccadic visual mislocalization are more intricate. For example, we recently observed that saccade motor commands in the superior colliculus change for different visual contexts, even if the generated saccades are the same. In a similar vein, we found here that perisaccadic mislocalization strength depends on the visual appearance of the saccade target!
Our results are intriguing because they add to a lot of evidence, by us and others, about how perisaccadic vision is more complex than just a simple model of gating or modifying the visual processing cascades of the brain by a deterministic eye movement vector. Rather, visual-visual and visual-motor interactions in different sensory and sensory-motor areas interact in complex ways. Indeed, we previously reached similar conclusions to this idea with our complementary work on perisaccadic suppression of visual sensitivity.
In the case of the current publication, we are very excited to follow up on our findings with neurophysiological studies linking motor commands in the superior colliculus to perisaccadic visual mislocalization, and to visual responses in the cortex. Stay tuned for upcoming publications highlighting our next steps in this very fascinating endeavor!