Abstract
The visual space in front of our eyes and the pictorial space that we see in a photo or painting of the same scene behave differently in many ways. Here, we used virtual reality (VR) to investigate size perception of objects in visual space and their projections in the picture plane. We hypothesize that perceived changes in the size of objects that subtend identical visual angles in pictorial and visual space are due to the dual nature of pictures: The flatness and location of the picture “cross-talks” (Sedgwick, 2003) with the perception of the depicted three-dimensional space. If the picture is at distance dpic and the depicted object at dobj, size-distance relations influence perceived relative sizes. The picture is expected to be scaled by a factor c*(dobj / dpic − 1) + 1 to match the object, where c is a constant between 0 and 1. In a VR environment, eight participants toggled back and forth between a view of an object seen through a window in an adjacent room, and a picture that replaced the window. Participants adjusted the picture scale to match the size of the object through 60 trials varying dobj and dpic. A multilevel regression indicated that the above model does not hold. Rather, we found a striking asymmetry between the roles of object and picture. If dobj was greater than dpic (object behind picture) then c was 0.005 (t(7) = 7.80, p < 0.001). In contrast, if dobj was less than dpic (object in front of picture), c was 0.33 (t(7) = 3, p < 0.001). We discuss this result in the context of a number of different theories that address the particular nature by which the flatness of the picture plane influences the perception of pictorial space.