Influence of a sensorimotor conflict on the memorization of a path traveled in virtual reality.

Studies of visual-vestibular and vestibular-proprioceptive interactions suggest that prolonged exposure to sensory conflicts induces a modification of the relation between sensory modalities for self-motion perception. With most models conflicts are solved by a weighting process. However, the brain could also switch between conflicting cues. The present study focused on the effect of mismatched visual and non-visual information on the reproduction of actively performed turns. Standing subjects viewed a virtual corridor in which forward movements were simulated at a constant linear velocity, and rotations were actually performed. They were asked to learn the trajectory and then to reproduce it from memory in total darkness. In the baseline condition, the relative amplitudes of visual and non-visual information for the rotations performed were the same, but were manipulated in the two 'sensory conflict' conditions. The results show that even when subjects did not notice the sensory conflict, the discrepancy between visual and non-visual information affected their ability to reproduce the angular displacements. In one conflict condition, subjects relied on visual information when asked to draw the trajectory traveled, yet reproduced rotations on the basis of non-visual information during active blindfolded movements. This dissociation suggests that for mental simulation of the same path, there are at least two cognitive strategies of memory storage and retrieval, using either visual or non-visual information, according to the task and the sensory context.