CONVERGENT DISPARITY DISCRIMINATIONS IN NARROW-BAND-FILTERED RANDOM-DOT STEREOGRAMS

Two experiments were reported which investigated convergent disparity discriminations [in humans] in unfiltered and narrow-band-filtered random-dot stereograms. Experiment I found that a given disparity (in the range 2.6''-20.8'') produced a very similar perceived relative depth regardless of the spectral content of the stereogram (in the range 2.5-16.2 c[cycles]/deg). Eye movements were not controlled. Experiment II measured exposure duration thresholds for disparity discriminations between 2 random-dot disparate areas. Disparity discriminations in the range 0''-13'' were possible in unfiltered stimuli at durations well below the latency for vergence eye movements. Discriminations in the range 0''-8'' were also possible below this latency for spatial frequencies in the range 2.5-16.2 c/deg. Low and high spatial frequency channels are probably not specifically related to large and small disparity mechanisms, respectively, at least within the disparity and spatial frequency ranges studied.