In the probed-sinewave paradigm—used to study the dynamics
of light adaptation—a small probe of light is superimposed
on a sinusoidally flickering background. Detection threshold
for the probe is measured at various times with respect to the
flickering background. Here we present such stimuli using three
methods: monoptic (the probe and the flickering background are
presented to the same eye), dichoptic (the probe is presented
to one eye and the flickering background is presented to the
other eye), and binocular (the probe and the flickering background
are both presented to both eyes). The results suggest that the
processing associated with detecting the probe is primarily
in the retina (or any place with monocular input). However,
the results also suggest a slight amount of processing
in the cortex (or any place with binocular input), particularly
at the higher frequency of flickering background used here (9.4
Hz vs. 1.2 Hz). A simple schematic model with three
ocular-dominance channels is consistent with the results.