Brightness discrimination following forebrain ablation in fish

Abstract

The effect of forebrain ablation on brightness discrimination in goldfish has been studied. Cardiac deceleration, a conditioned autonomic response, was used as the measure of discrimination in a series of goldfish. Normal and forebrainablated fish were trained to discriminate between two gray stimuli of different brightness. If the experimental animal made this brightness discrimination in thirty-five trials it was subsequently tested on a black and white stimulus pair to see whether the fish was capable of stimulus generalization. If the fish did not make the brightness discrimination, it was trained to discriminate a different set of stimuli to show that it was conditionable. It was found that forebrain ablation did not result in any loss in the ability of these operated fish to make a brightness discrimination. In fact, the operated animals learned the brightness discrimination more rapidly than normal animals. Furthermore, the forebrainless fish were able to generalize to another brightness problem. Control tests were run to substantiate this finding.