Visuomotor adaptation to excessive visual displacement in video see-through HMDs

Abstract

A video see-through head-mounted display (VSHMD) is a modified HMD having an additional small digital camera set (see-through camera set) attached in front of the HMD, which allows users to view the real scene along with virtual information in digitally mixed form. However, although VSHMD has potential utility in augmented reality applications, the visual displacement problem must be overcome. This problem is caused by the distance between the see-through camera and human eye and induces visuomotor performance deterioration. Previous studies have revealed that human adaptation improves the visuomotor performance over time, by rearranging the proprioception. In this study, we extend the visual displacement excessively to 300 mm and investigate the eye-hand and eye-foot visuomotor coordination in two experiments. In Experiment 1, the prism adaptation paradigm is used to compare task performance under various visual displacement conditions. In Experiment 2, the procedures of Experiment 1 are implemented on 3 consecutive days to evaluate the relatively long-term adaptation trend. The results reveal distinct adaptations under all conditions. When excessive visual displacement is unavoidable, sufficient training can improve task performance, similar to the previously discovered perceptual adaptation. However, with increased visual displacement, the task performance improvement decelerates significantly. This improvement attenuation increases as the task performance becomes close to that achieved under bare eye conditions. Although humans can adapt to a large amount of visual displacement, a serious usage problem arises because of this slow adaptation improvement trend.