Imprinting: Effects of discrepancy from rearing conditions on approach to a familiar imprinting object in a novel situation.

Abstract

For the purpose of manipulating a discrepancy between rearing and testing conditions, chicks were individually raised with an imprinting object in small or large cages and were given a series of approach trials to the object in a larger novel chamber at 48 h of age. Chicks were raised in small or large cages with either a blue ball or piece of yellow sponge. Throughout testing, large-cage chicks, for which the chamber was less discrepant, approached more quickly than small-cage chicks. On later trials, chicks raised with the blue ball came to approach more quickly than those raised with the yellow sponge. When chicks were again raised with an object in small or large cages, but half were inside transparent inner cages which restricted movement of those chicks to the area of the small cages but maintained the perceptual differences between large and small cages, large-cage chicks again approached the imprinting object more quickly in testing, regardless of the presence of the inner cages. The results confirm the perceptual-learning hypothesis that the degree to which chicks respond to a test chamber as novel determines the approach to an imprinting object.