On spectral sensitivity in the goldfish. Evidence for neural interactions between different "cone mechanisms".

Spectral sensitivity was measured in freely moving, light adapted goldfish using a behavioral training technique. The curve reveals 3 pronounced maxima at 470, 540 and 660 nm. Compared with the absorption spectra of the cone photopigments with lambda max at 450, 530 and 625 nm, the maxima were much narrower and shifted towards longer wavelengths. Results under chromatic adaptation indicate that spectral sensitivity measured under the white adaptation light is determined by inhibitory interactions between the spectrally different "cone mechanisms". For the short-wave maximum, a summation process probably has to be assumed in addition.