Behavioural Measures of the Spectral Sensitivity of the Dark-adapted Goldfish

Abstract

THE eye of the goldfish has a single rod photopigment with a peak spectral absorption at about 522 nm, together with three different photopigments of the cones¹. The spectral sensitivity curve of the electroretinogram (ERG) in the dark-adapted goldfish has been found to be considerably broader than the rod pigment absorption function, suggesting a significant contribution of cone response to the dark-adapted ERG². This ERG result contrasts with those from very similar experiments on humans which show that the spectral sensitivity of the scotopic ERG is very closely related to the absorption spectrum of the visual pigment of the rods³. To elucidate more fully the relations between the psychophysics and physiology of goldfish vision, a behavioural method was devised to determine spectral sensitivity functions in fish. This method has previously been used to measure the spectral sensitivity of the goldfish in light-adapted conditions^4,5.