DISSOCIATION OF HEMISPHERIC EXPLOITATION OF RODS AND CONES FOR SIMPLEDETECTION

Sergent (1982a, 1982b, 1982c) proposed that stimuli carrying high lumi nous energy will be better detected in the right field (left hemispher e) and stimuli carrying low energy in the left visual field (right hem isphere). A photoreceptor-based model could explain the same effects a s well as several others (eccentricity effects, retinal adaptation eff ects). Braun, Mailloux, and Dufresne (1995) suggested that cones might favor right field stimuli and rods might favor left field stimuli. We implemented a series of near-threshold simple detection experiments c omprising stimuli varying along four dimensions (color, eccentricity, duration, and size) in dark-adapted subjects. Consistent and significa nt right field advantages accrued for near-meridianal foveal red stimu li, but there were no field effects for eccentric blue stimuli. An alt ernative to Sergent's stimulus energy model and the photoreceptor-base d model, namely a parvocellular-magnocellular model, is proposed.