Abstract
When we perform saccade eye movements, we remain unaware of the motion that is produced by the high-speed retinal displacement. Omission of peri-saccadic motion is not the result of a general trans-saccadic blindness since are well able to perceive motion during saccades. Here, we tested whether the sensorimotor system learns and predicts the retinal motion that it produces by its own saccades. We asked participants to perform saccades to a target. In each trial, a high-speed grating was presented in the top or bottom half of the screen. The grating became visible only during saccade execution when the saccadic velocity counteracted the external velocity. Subjects reported the location of the grating (up or down). We found that when the grating was designed such that the resulting retinal motion velocity matched the velocity naturally occurring for that saccade amplitude, grating detection sensitivity was higher than when it did not match. In entrainment trials, we experimentally coupled a certain saccade amplitude (5º or 10º rightward saccades) to a certain retinal velocity (e.g. 100°/s) and then tested grating detection sensitivity. In probe trials, we tested sensitivity when either the saccade amplitude or the grating velocity was different than in entrainment. We found that sensitivity for grating detection was reduced only when saccade amplitude and external motion matched those of the entrainment trials. The reduction in sensitivity was even saccade vector specific and disappeared when changing the saccade amplitude although the retinal motion was kept identical to entrainment. Our data reveal that the sensorimotor system habituates to the retinal motion that corresponds to a given saccade amplitude. In real life, this is the motion that the system produces through it own saccades. In conclusion, the sensorimotor system stores and attenuates motion contingent on the saccades it commands.