Evidence for a "Freezing Motion in Depth Illusion"
Max R. Dürsteler  Mai 2006

Smoothly changing foreground motion in depth

Surround motion in depth changes induce jerky foreground motion in depth perception

Foreground motion in depth changes do not disturb the smoothness of the surround motion in depth perception


VCD-quality 2.9 MB

The first stereo-pair movie shows a simple motion-in-depth sequence induced by a sinusoidally changing horizontal disparity of a textured disk. The disparity of the disk with the houses varies with a frequency of 0.1 Hz between the mean horizontaly disparity (0%) of the surround with the forest and the disparity of the red fixation spot (disparity 1% of the display's width).


SVCD-quality 2.9 MB

If we change the disparity of the surround (forest) (frequency 0.4 Hz, disparity amplitude 0.025% of the display width), the disk with the houses appears no longer to move smoothly in depth: it seems to freeze, when surround and foreground move in the same direction, and to jump, if they move opposite each other.


VCD-quality 2.8 MB

Like the freezing rotation illusion, the disparity induced freezing motion in depth illusion is assymetric: while changes of the surround disparity induce temporary freezing in the perception of the foreground motion in depth perception, changes in the foreground disparity do not disturb the perception of the surround motion in depth. In our movie, the surround (forest)  is moving sinusoidally (0.1 Hz) between the ground plane (0 disparity) and the fixation spot at the near disparity of 1% of the displays' width. The fast changes (0.4 Hz) of the foreground (houses) with an amplitude of 0.25% do not distub the impression of a smoothly surround.
Freezing Rotation Illusion web pages: 1 & 2
Visual Illusion Contest 2006 Contribution