2D motion aliasing yielding 3D ambiguity. A study with variants of a Necker cube.

The 2D projection of a rotating Necker cube yields an ambiguous 3D interpretation based on both 2D shape and kinetic depth information. The present study shows that the alternation rate of the two 3D interpretations is constant with the rotation speed up to some critical value (around 25 turns/min for a cube whose sides subtend 2.5 deg) and increases monotonically thereafter.

Equivalent luminance contrast of red-green drifting stimuli: dependency on luminance-color interactions and on the psychophysical task.

The equivalent luminance contrast (EqLC) of red-green drifting stimuli was assessed by three independent methods. The first method [method (a)] consisted in adjusting the luminance contrast of a yellow, equichromatic stimulus to match the direction-discrimination performances that were obtained with a red-green, equiluminant stimulus. The second method [method (b)] was a replica of the standard motion-cancellation technique proposed by Cavanagh et al.