THE ROLE OF HEAD-CENTRIC SPATIAL REFERENCE WITH A STATIC AND KINETIC VISUAL DISTURBANCE

A static or kinetic visual disturbance affects subjects' ability to es timate the direction of the gravitational vertical. This kind of error is increased by a head roll inclination. In two experiments, we combi ned head orientation with a static (Experiment 1: tilted frame) versus kinetic (Experiment 2: rotating disk) visual disturbance. The results showed that with a static visual disturbance, the increase of errors in the inclined head condition was mainly the consequence of a postura l head effect like an Aubert effect. On the contrary, with a kinetic v isual disturbance, it appears that the disk effect increases with head inclination. However, individual errors observed with the head inclin ed in front of a stationary disk were systematically correlated with t he errors triggered by the same head inclination in front of a rotatin g disk These observations confirm that the head axis spatial reference plays an important role in orientation perception, whatever the head position and the kind of visual display.