Abstract
The majority of experimental studies on three-dimensional (3D) visual-spatial processing have been conducted using traditional 2D displays. We were interested in the contribution of immersion to 3D image transformations and compared subjects' performance on spatial transformation tasks within traditional 2D, 3DNI (stereo glasses), and 3D-immersive (3DI -head mounted display with position tracking) environments. Fourteen participants completed a Perspective-Taking Ability (PTA) test where they imagined transforming their own perspective to a figure's perspective in a computerized scene and pointed to one of the several objects in the environment from the figure's perspective. In addition, 11participants completed Shepard and Metzler Mental Rotation Task (MRT), in which they mentally rotated 3D objects along the picture (X), vertical (Y), or depth (Z) axes. While the patterns of subjects' responses were not significantly different in 2D and 3DNI environments, we found a unique pattern of responses in the 3DI environment, suggesting that immersion trigger significantly greater use of egocentric object coding and visuo-motor strategies than the two other non-immersive environments. Specifically, for PTA, subjects made significantly more egocentric errors (e.g., errors related to body-coordinate system, such as confusion between right-left and back-front responses) than in the two other environments suggesting that 3DI triggered more egocentric coding. Furthermore, for MRT, while no differences were found between X-axis and Z-axis rotation in 2D and 3DNI environments, in 3DI, Z-axis rotations took significantly longer than X-axis rotations suggesting the greater use of visuo-motor strategies. Overall, our findings point out that 3DI environments are different from 3DNI and 2D, and that immersion is necessary to provide adequate information for building the spatial reference frame needed for motor planning and egocentric encoding.