Modification of ducklings' filial behavior by aversive stimulation.

Three experiments examined the effects of aversive stimulation in the context of imprinting. In Experiment 1, newly hatched ducklings were electrically shocked in either the presence or absence of an imprinting stimulus, and both their tendency to follow the stimulus when it was presented alone and their preference for it over novel stimuli were subsequently assessed. The results indicated that the shock enhanced the subjects' tendency to follow the imprinting stimulus in the nonchoice situation regardless of whether the ducklings were shocked in its presence or absence. If, however, the electrical shocks were associated with the presence of the imprinting stimulus, they also reversed the ducklings' usual preference for the imprinting object over the novel stimuli. Comparable effects were obtained in the second experiment in which 5-day-old ducklings were electrically shocked in either the presence or absence of a novel, fear-eliciting imprinting stimulus. In Experiment 3, electrical shock was administered to newly hatched ducklings independently of their exposure to an imprinting stimulus, and it was found that, relative to older ducklings that received the same treatment, the newly hatched subjects subsequently displayed less emotionally in fear-eliciting situations. The results were interpreted as suggesting that there are at least three distinct effects of aversive stimulation in the context of imprinting-motivational, associative, and developmental.