INFLUENCE OF GRAVICEPTIVES CUES AT DIFFERENT LEVEL OF VISUAL INFORMATION-PROCESSING - THE EFFECT OF PROLONGED WEIGHTLESSNESS

We evaluated the influence of prolonged weightlessness on the performa nce of visual tasks in the course of the Russian-French missions ANTAR ES, Post-ANTARES and ALTAIR aboard the MIR station. Eight cosmonauts w ere subjects in two experiments executed pre-flight, ill-flight and po st-flight sessions. In the first experiment, cosmonauts performed a ta sk of symmetry detection in 2-D polygons. The results indicate that th is detection is locked in a head retinal reference frame rather than i n an environmentally defined one as meridional orientations of symmetr y asis (vertical and horizontal) elicited faster response times than o blique ones. However, in weightlessness the saliency of a retinally ve rtical axis of symmetry is no longer significantly different from an h orizontal asis. In the second experiment, cosmonauts performed a menta l rotation task in which they judged whether two 3-D objects presented in different orientations were identical. Performance on this task is basically identical in weightlessness and normal gravity.