"Shear" verticali, orizzontali e percezione stereoscopica di superfici inclinate
The deformation theory claimed by Koenderink and van Doorn (1976) suggests that the amount of deformation between two simultaneous binocular images can be used by the visual system to compute stereoscopic inclination. This theory states that there should be no statistical difference between the perceived inclination of a ramp surface when two stereoscopic images are related by a vertical shear transformation containing vertical disparities, and the perceived inclination of a ramp surface when two stereoscopic images are related by a horizontal shear transformation containing horizontal disparities. In the present experiment, subjects estimated the perceived inclination of many random dots ramp surfaces, both when the two stereoscopic images were related by a vertical shear transformation, and when the images were related by a horizontal shear transformation. Even if the observers were clearly able to perceive a ramp surface in the presence of a vertical shear transformation, the results of this experiment did not support the deformation theory because the perceived inclinations in the two experimental conditions (vertical and horizontal shear condition) were statistically different.
