Neural and psychophysical correlates of induced interocular transmission disparities

We investigated the influences of luminance and temporal asymmetries on the pattern visually evoked potential (pVEP) as a function of stimulus contrast. Monocular and binocular baseline steady-state (ss) and transient (t) pVEP's were recorded on 10 visually normal young adults using a reversing checkerboard pattern ranging in contrast from 4 to 65%. Neutral density (ND) filters were then placed before the right eye in 0.5 ND increments (maximum 3.5 ND), as monocular and binocular pVEP's were recorded. Visual acuity, brightness sense, and the Pulfrich effect were then measured to similar luminance and temporal asymmetries. Neural and psychophysical data were compared. Monocular visual acuity and pVEP results appeared to be luminance-dependent. Brightness sense, the Pulfrich effect, and binocular pVEP amplitudes appeared to be temporarlly dependent. The binocular pVEP amplitude seemed to be less sensitive to temporal asymmetries for lower contrast targets.