On the Determinants of Size-Constancy in a Virtual Environment

International audience—An important aspect of a subject’s perception ofvirtual objects in a virtual environment is whether the size of theobject is perceived as it would be in the physical world, which isnamed size-constancy. The ability of subjects to appreciatesize-constancy in an immersive virtual environment was studiedwhile scene complexity, stereovision and motion parallax visualfactors were manipulated resulting in twelve different viewingconditions. Under each visual condition, 18 subjects made sizejudgments of a virtual object displayed at five different distancesfrom them. Responses from the majority of our populationdemonstrated that scene complexity and stereovision have asignificant impact on subjects’ ability to appreciate size-constancy.In contrast, motion parallax produced by moving the virtualenvironment or by the movements of the observer alone provednot to be a significant factor in determining size-constancyperformance. Consequently, size-constancy is best obtained whenscene complexity and stereovision are components of the viewingconditions