Eye eccentricity modifies the perception of whole-body rotation

In order to explore the effect of gaze orientation on whole-body rotation perception, ten healthy participants were rotated in the dark while fixating on a visual target located either straight ahead or 15° to the right. A vestibular-memory contingent saccade paradigm was used to estimate the rotation perception. The results attest to the participants’ ability to accurately perceive their rotation, based solely on the intrinsic inputs (somesthetic and mainly vestibular), since the correlation between the imposed body rotation and the saccade amplitude was significant and positive. However, the rotation perception was less accurate and of lesser magnitude when the gaze was deviated in the opposite direction to the rotation than when it was either straight ahead or deviated in the direction of the rotation. This can be interpreted as the perceptual equivalent of Alexander’s law.