Stereokinetic Interaction Effects Involving Static and Slowly Moving Identical Figures

Here a new depth effect evoked by the spatial and temporal interaction in 2-D of a slowly moving circle (optimally at 0.6 rads/sec.) with an identical static circle is reported. Typically, respondents report that with increasing adjacency, commencing with separations of a few diameters, the moving circle appears in a different plane of depth to the static circle, it then usually appears to “dip” onto the static circle and after complete coincidence with it to rise away from it. This effect, together with a number of associated descriptions are commented upon, in addition to observations when viewing overlapped static circles and overlapped circles in motion, this latter stimulus condition evoking the stereokinetic effect. The authors have previously suggested that contour “sliding,” which simulates motion parallax, is the key to understanding stereokinesis. The stimulus conditions giving rise to this new effect directly simulate the motion parallax information present in a retinal image.

Stereokinetic Effects with Sharp and Fuzzy Illusory Contours

A black, 8-shaped pattern, whose centre of gravity is in the centre of a rotating disc, appears to split into two black discs rotating with phenomenal independent motion, orientation stability, and sliding of one on the other. The type of observed movement, the order of overlapping, and the extent of the stereokinetic depth in relation to the contour type and different dimensions of the pattern were investigated. The experimental data show that a fuzzy contour facilitates the stereokinetic effect. Furthermore, the extent of the stereokinetic depth has been found to be greater in case of fuzzy contour and vertical orientation of the pattern. These results are in contrast with the models in which this effect is considered as a problem of minimisation of distances or velocities. A vector model of the observed movement and an interpretation of the overlapping based on an energy approach are proposed. A tentative explanation of the stereokinetic depth for our patterns is put forward.

Using the Stereokinetic Effect to Convey Depth: Computationally Efficient Depth-from-Motion Displays

Recent developments in microelectronics have encouraged the use of 3D data bases to create compelling volumetric renderings of graphical objects. However, even with the computational capabilities of current-generation graphical systems, real-time displays of such objects are difficult, particularly when dynamic spatial transformations are involved. In this paper we discuss a type of visual stimulus (the stereokinetic effect display) that is computationally far less complex than a true three-dimensional transformation but yields an equally compelling depth impression, often perceptually in discriminable from the true spatial transformation. Several possible applications for this technique are discussed (e.g., animating contour maps and air traffic control displays so as to evoke accurate depth percepts).