One second interval production task during post-rotatory sensation.

Temporal intervals production of one second was found to be more variable during self-motion compared to no motion situations. Moreover, the temporal intervals production rhythm during self-motion deceleration decreased whereas it increased during self-motion acceleration, whatever the direction of motion. As somatosensory cues were not excluded in this previous experiment, we now examined whether the same temporal perturbation would occur without variable somatosensory information. In order to isolate the contribution of the vestibular system from that of the somatosensory system, the participants were required to perform a one second temporal interval production task (pressing a button each second) during the post-rotatory illusion following self-rotation. The intervals produced during the vestibular illusion were compared to those produced before the imposed rotation and during self-motion. The production regularity was affected as the temporal intervals were more variable with vestibular stimulation (real and illusory self-motion) than without. Furthermore, during post-rotatory illusion, the production rhythm decreased along the trial, as it was observed during self-motion deceleration. These findings suggest that vestibular stimulation (even vestibular illusion) impaired time estimation.