The effect of perceptual modality, hand scale, and gesture dynamics on the perception of object extent in real and virtual environments
Jeffrey Koivisto Caird · 1994
Virtual environments (VE) hold potential insight into many questions about human-machine and human-environment relationships. The ability of the human to perceive and detect small differences in size within real and virtual environments was the focus of this research. Towards this objective, a series of three experiments were conducted that examined the perception of size, whole-hand gestures, and hand scale relative to object size within a virtual environment system. The purpose of the first experiment was to determine the relative contribution of vision and touch to the perception of object size. Results indicated that people were able to discriminate between objects regardless of perceptual modality or presentation medium, however, linear performance models revealed greater variability in perceived accuracy for virtual conditions. The second experiment sought to determine whether gestures rather than direct grasping of the cylinders affected the accuracy of perceived size. When objects could be grasped with a fist gesture and manipulated, the perception of object size was significantly more accurate than when they could not. The third experiment examined the effect of changes in referent hand size on the perception of virtual environment scale. Results showed that hand size affected the perception of object size and thus world scale. Together these results provide insight into how people actively seek clear perceptual information when limited exteroceptive, exproprioceptive, and proprioceptive information is available in virtual environments. The results are framed using the theoretical concept of affordance (Gibson, 1977). A discussion of the usability of head-mounted displays and whole-hand input interfaces is also given.