Reconsideration on primacy effect of imprinting in ducklings

Abstract

Three experiments were carried out to determine whether initial imprinting to an artificial object wears off when a Peking duckling (Anas platyrkynchos) is later exposed to a conspecific. Two groups of ducklings (groups I and P) were studied. The ducklings in group I had no social contact except during experimental sessions, whereas those of group P did. Experiment 1 showed that the effect of social contact on the ducklings' subsequent responses to the original object was not significant. Experiment 2 showed that the shaped and maintained operant response rate to the imprinting object decreased sharply in ducklings from both groups when the conspecific was used as a contingent event. Experiment 3 showed that ducklings from both groups preferred the imprinting object over the conspecific in a simultaneous choice situation. Furthermore, when the imprinting object was not presented, the ducklings from group I avoided the conspecific, while those from group P approached it. These results indicated that the initial imprinting to an artificial object does not wear off even if ducklings are later exposed to the natural conspecific and establish some preference for it, supporting the primacy effect in imprinting.