Cornelis E V K, van Doorn A J, de Ridder H, 2002, "Reflecting a picture of an object: what happens to the shape percept?" Perception 31 ECVP Abstract Supplement
Reflecting a picture of an object: what happens to the shape percept?
E V K Cornelis, A J van Doorn, H de Ridder
Making a picture of a three-dimensional object results in losing the third dimension, namely the distance range. Yet, pictorial depth cues make a three-dimensional interpretation possible. The three-dimensional interpretation of the depicted object is called the pictorial relief. An object photographed from several viewpoints results in different pictures varying in structural information. However, mirror-image versions of a photograph depicting an object from one (arbitrary) viewpoint, contain the same structural information. We investigated the influence of reflection of the picture on the three-dimensional interpretation of the depicted object. Six pictures of a torso, taken from different vantage points, were reflected (i) about the horizontal axis and (ii) about the vertical axis. Participants performed local attitude settings by adjusting a thumbtacklike figure so that it seemed to be painted onto the torso's surface. From these settings, the pictorial reliefs of all stimuli were constructed. Pairwise comparison between the pictorial reliefs of the original pictures and their mirror-image counterparts revealed differences that can be described by shears. Besides overall shears, piecewise differentiations occurred corresponding to different surface regions on the torso. This type of transformation is exactly what would be expected if observers change their mental viewpoint in an appropriate way.
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