Effects Of Surface Luminance And Texture Discontinuities On Reachableness In Virtual Reality

Perceiving distance is at the heart of everyday actions like reaching for a cup of coffee. This action depends on at least the biomechanical restrictions of the actor (i.e., arm-length) and the physical distance between the cup and the actor. Environmental variables may also impact perceived distances for reaching. For a given perceptual judgment, these variables might be thought of as static, i.e., stable or unchanging. But the perception-action process involves the unfolding of dynamic variables such as exploratory movement. Four experiments were conducted to investigate the roles of two "static" environmental variables (surface luminance and surface texture discontinuity) and two "dynamic" exploratory-movement-related variables (mean head displacement and multifractality of head movement) in an object-reachableness task in virtual reality. We found that surface texture discontinuities and surface luminance can make objects appear more reachable, but not always. We also found that in more complex scenarios, the inclusion of the dynamic variables improved model fits over the static models. We suggest that movement is the driver of perception and, that in attempting to model a given perceptual process, the researcher must consider the underlying characteristics of variables tested and seek out variables related to the unfolding dynamics of the perception-action cycle.