Effects of Novelty On Taste-Avoidance Learning in Chicks

Five experiments were conducted to investigate the effect of novelty on visually-mediated taste-avoidance learning in domestic chicks. In experiments l a and b, chicks were reared with either uncoloured or blue fluid in their home cages, and then required to discriminate between blue and uncoloured fluids that were either palatable or unpalatable (quinine-adulterated). For some chicks the distasteful fluid was novel in appearance, for others it was familiar. In both experiments chicks readily discriminated between a novel unpalatable fluid and a familiar palatable one, but failed to discriminate between a familiar unpalatable fluid and a novel palatable one. This failure to discriminate resulted from avoidance of the palatable fluid. In neither experiment did novelty enhance the rate of avoidance learning. Experiment 2 tested more directly the effect of novelty on speed of avoidance learning. Chicks were reared on either red or blue palatable fluid, then tested with either red or blue distasteful fluid. Avoidance learning was more rapid when the distasteful fluid was novel in colour, in both red-reared and blue-reared chicks. Experiment 3 investigated the inability of chicks to discriminate between a familiar unpalatable fluid and a novel palatable one, demonstrated in experiment 1. Chicks were required to discriminate between different-coloured palatable and unpalatable fluids when both were familiar in appearance (experiment 3a) or when both were novel (experiment 3b). Discrimination occurred in the first case but not in the second. In addition, avoidance learning was slower when both unpalatable fluids were familiar. I conclude that (a) novelty faciliates visually-mediated taste-avoidance learning in chicks and (b) the failure of chicks to discriminate a novel palatable fluid from a familiar unpalatable one depends on the relative novelty of the palatable fluid and not on the relative familiarity of the unpalatable one. The results are discussed in the context of warning coloration and are explained in terms of an interaction between unlearned and learned avoidance tendencies.