Can observers perceive depth in virtual environments within extrapersonal space?

In this paper, we address extra-personal depth perception in virtual worlds. Mainly, we focus on the contribution of stereopsis in estimating the distance of virtual objects appearing around two meters and beyond far from the viewer. Our aim is to answer the following fundamental question: "do humans integrate similarly the stereoscopic disparity to derive virtual objects depths ranging from two meters to infinity"? In this work, we reduced the cue's set to the sole stereopsis or disparity by using the size-distance paradox. We believe that this reduction is necessary to deal with the complexity of the visual perception and the processes it involve. Indeed, many experimental studies have shown that technological constraints and conceptual limitations cause depth misestimations within stereoscopic displayed virtual environments. However, there is no clear idea about individual contributions of the visual cues and the ways they are integrated. This paper presents the experiments we performed in order to quantify the contribution of the stereoscopic disparity. According to the obtained performances, we found two groups: a group of subjects able to perceive correctly depths and a second group misestimated depths. In addition, we found that the gender, age and inter-pupillary distance affect subjects performances.