Apparent Depth Threshold for the Benussi Effect
Using the single staircase psychophysical method, the apparent depth threshold for the Benussi effect was determined for 5 observers. The threshold occurred at an eccentricity of 2r/3, where r equals the radius of the larger circle expressed in millimeters.
Shape, Height and Angular Movement in Stereokinesis
Cues affecting the apparent height (depth) of a stereokinetic ‘cone’ were investigated by comparing heights for pairs of rotating figures. Apparent height was shown to be independent of the number of bands on the figure and of the geometric perspective by which it was drawn. On the other hand, apparent height was strongly dependent on eccentricity within the figure, with maximum apparent height being achieved at full eccentricity. The reason for the existence of such a definite maximum remains obscure.
Perception of Depth in Rotating Objects: 3. Asymmetry and Velocity as the Determinants of the Stereokinetic Effect
When a flat stimulus is rotated in the frontoparallel plane about a horizontal axis that is an extension of O's line of regard, the apparent depth of the stimulus is enhanced. The enhancement was entirely a function of peripheral asymmetry. The apparent depth in the static figure, internal structure, or taper in the periphery did not augment the rotation-enhanced depth. The magnitude of the enhancement was constant for any series of stimuli, such as a series of overlapping circles with increasing overlap. The apparent depth also increased as a function of the speed of rotation.