Bezold-Brücke phenomenon of the far peripheral retina

The Bezold-Brücke phenomenon was measured during the cone-plateau period of the long-term dark-adaptation curve at 25 degrees, 40 degrees and 60 degrees in the nasal field of view, and at 40 degrees and 70 degrees in the temporal field. In striking contrast to previous measurements of the B-B phenomenon the present results generally show that an increase of the luminance level in the middle- and long-wave regions of the spectrum produces, respectively, a trend toward green and red instead of toward yellow. The present results are explained on neural rather than on photochemical mechanisms.