Loss of hue discrimination in forebrain-ablated fish

Abstract

The effect of forebrain ablation on hue discrimination in fish has been studied. Cardiac deceleration, a conditioned autonomic response, was used as the measure of discrimination in a series of goldfish. Electric shock was the unconditioned stimulus. Forebrain-ablated fish were trained to a red and a green stimulus selected to be of equal brightness. These fish were subsequently tested on red and green stimuli of known brightness, as perceived by these experimental animals. Normal fish in this situation reacted to the test stimuli on the basis of their wavelength characteristics, but forebrainless animals reacted only to the brightness and not to the wavelength characteristics of the test stimuli. Other control tests substantiate this finding.