Performance of a simple aiming task in hypergravity: I. overall accuracy.

BACKGROUND

Visuo-motor performance is known to be affected by exposure to hyper-gravity (hyper-G), but the underlying mechanisms remain to be determined; the present study investigated the role of target mislocalization.

METHOD

Subjects pointed before, during and after exposure to hyper-G at targets without seeing their hand. Target positions were displayed: a) throughout each pointing response; b) before response onset; or c) in normal gravity prior to a set of movements.

RESULTS AND CONCLUSIONS

For all display conditions, subjects pointed higher in hyper-G than in normal gravity from the first movement on. We attribute the discrepancy between this finding and previous results (8, 12) to different movement strategies. The effects of hyper-G on pointing performance were small, but sustained when targets were displayed before or throughout each movement, but they were large and transient when targets were memorized in normal-G. We conclude that too-high pointing in hyper-G cannot be simply explained by the "elevator illusion," and propose a tentative interpretation based on known perceptual deficits.