Perceived gravitoinertial force during vection.

Background: When we ride on a roller coaster, our experience of self-motion is accompanied by salient changes in gravitoinertial force. Here we examined whether a similar relationship exists between visually induced self-motion (vection) and perceived gravitoinertial force.

Methods: There were 15 stationary subjects, each wearing a weight jacket, who were exposed to visual displays simulating upward, backward, or no self-motion. At the end of each 30-s display exposure, subjects: 1) rated the strength of their vection experience; and 2) had the experimenter add/remove weights from their weight jackets to recreate their perceived weight during exposure to the stimulus display.

Results: We found that upward vection increased and downward vection decreased perceived weight. Importantly, the size of these perceived weight changes depended on the strength of the vection experience.

Conclusions: We conclude that the observed strong relationship between vection and perceived weight stems from the brain's attempt to reconcile the inputs from the different self-motion senses. The current findings have important implications for all simulated self-motions either in virtual reality or in vehicle simulators (particularly fixed-base flight and driving simulators).