Absolute egocentric distance judgments are improved after motor and cognitive adaptation within HMD

In full-cue, real-world environments, people are accurate at visually-directed actions to targets on the ground. The same distance estimation tasks conducted in virtual environments using head-mounted display (HMD) systems show that people act as though the environment is smaller than intended. The explanation for this difference between actions in real and virtual environments is unknown. Our current study investigated influences of adaptation within the HMD on subsequent distance judgments. Two forms of feedback were evaluated using two distinctly different response measures. In a pre-test, subjects indicated egocentric distances to targets on the floor using one of two measures: blind walking or verbal reports. In the adaptation period, they experienced one of two interventions. A visual-motor intervention involved the continuous visual and motor feedback of walking with eyes open to previously viewed targets. A non-visual-motor intervention involved walking with eyes closed until the subjects were told that they reached the previously viewed target. After this adaptation period, subjects completed a post-test in which they performed the same task as in the pre-test. Distances were underestimated in the egocentric distances by approximately 30 for both tasks during the pre-test, consistent with previous results. Notably, subjects became significantly more accurate at both blind-walking to targets and verbal reports of distance after both adaptation experiences. The results indicate that both cognitive and motor indications of distance can be recalibrated in the HMD and suggests that recalibration can be caused by effects other than the interaction of sensory modalities indicating the speed of travel