Detection/discrimination in the long-wavelength pathways.

We apply the simultaneous detection/discrimination method to the mechanisms mediating detection of longand middle-wavelength test lights. The results suggest the following: (1) a test light detected by a signal initiated primarily in the long-wavelength receptors will be ultimately detected by different sets of nerve cells, depending upon the background illumination. (2) The discriminability of two test lights depends upon their duration, even when the lights are equated (at threshold) for visibility.