submitted abstract to Europian Conference on Visual Perception, 22-26 August 1999, Triest, Italy
Keywords: SYNCHRONY, STEREOPSIS
Inter-ocular asynchrony can produce depth illusion in dynamic noise patterns (Tyler 1974). We introduced asynchrony in dynamic random dot stereograms: Inter-ocular delays (13.4ms) were disturbuted randomly and evenly between the pixels of two image profiles. The effects of noise and contrast were very similar to those for conventional stereograms and asynchrony did not interfere with stereopsis (Logistic regression, P>0.1). One possible explanation is that binocular cells restructure their receptive field to compensate inter-ocular delay. If so, after adaptation to asynchronous input, a brief view of a static stereogram would be difficult to discriminate. Subjects were asked to view either an asynchronous or a conventional dynamic stereogram 2 seconds before and after a 13.4ms exposure to a static stereogram, then answere a 8-AFC task (position of a circle) about the brief stimulus. Error rates were lower after adaptation to asynchronous stereogram. We could show a small, but significant difference between two groups (P < 0.01). Results are against the first hypothesis and suggest that the underlying neural mechanism of stereopsis is broadly tuned for temporal asynchronies between two eyes.
Ref.
Tyler, C.W. 1974, Stereopsis in dynamic visual noise, Nature 250: 781-782
