Pitch body orientation influences the perception of self-motion direction induced by optic flow

Aurore Bourrelly (1) , J. -L. Vercher , L. Bringoux (2)

1 LAMIH - Laboratoire d'Automatique, de Mécanique et d'Informatique industrielles et Humaines - UMR 8201
2 ISM - Institut des Sciences du Mouvement Etienne Jules Marey

We studied the effect of static pitch body tilts on the perception of self-motion direction induced by a visual stimulus. Subjects were seated in front of a screen on which was projected a 3D cluster of moving dots visually simulating a forward motion of the observer with upward or downward directional biases (relative to a true earth horizontal direction). The subjects were tilted at various angles relative to gravity and were asked to estimate the direction of the perceived motion (nose-up, as during take-off or nose-down, as during landing). The data showed that body orientation proportionally affected the amount of error in the reported perceived direction (by 40% of body tilt magnitude in a range of +/- 20 degrees) and these errors were systematically recorded in the direction of body tilt. As a consequence, a same visual stimulus was differently interpreted depending on body orientation. While the subjects were required to perform the task in a geocentric reference frame (i.e., relative to a gravity-related direction), they were obviously influenced by egocentric references. These results suggest that the perception of self-motion is not elaborated within an exclusive reference frame (either egocentric or geocentric) but rather results from the combined influence of both. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Mots clés: Spatial perception; Body orientation; Heading; Self-motion; Reference frame; Geocentric; Egocentric

Domaines: Neurosciences

Aurore Bourrelly, J. -L. Vercher, L. Bringoux. Pitch body orientation influences the perception of self-motion direction induced by optic flow. Neuroscience Letters, 2010, 482 (3), pp.193-197. ⟨10.1016/j.neulet.2010.07.028⟩. ⟨hal-01436028⟩