Visual and flavor cues in toxicosis conditioning of codfish

Abstract

Codfish were first trained to strike a target suspended in a tank to obtain food. Different groups were then exposed to either a visually distinctive target, a novel food, or a combination of both prior to toxicosis induced by an injection of lithium chloride. After recovery from the drug, the associability of these cues with toxicosis was tested by requiring each fish to choose between two distinctive targets for two kinds of food. One choice was a “safe” target and food; the other consisted of a conditioned target and conditioned food or (depending on the conditioning treatment) a novel target and either a novel food or a conditioned food. The strongest aversion was shown by the group conditioned to both target and food. Less aversion was shown by the fish conditioned to the visual cues of the target alone. A third group learned to avoid a novel target which produced a food previously associated with toxicosis. A second experiment showed that an aversion could be obtained even when the only cue present in testing which could mediate a discrimination was a conditioned target.