Dynamic stereoacuity: a comparison of electrophysiological and psychophysical responses in normal and stereoblind observers.

We compared stereoscopic thresholds determined psychophysically and by using visually evoked potentials in normal adult and stereoblind subjects. For normal observers there was a strong linear relationship between visual evoked potential amplitude and disparity (r = 0.86 on average). However, stereoblind observers' responses showed no relationship to disparity (r = 0.18 on average). For normal observers, log visual evoked potential stereo thresholds determined by an extrapolation procedure were on average within 0.17 octaves of the psychophysically determined log thresholds. They did not differ significantly from psychophysical thresholds, and they correlated significantly with behavioral thresholds (r = 0.86).