Imprinting on time-structured acoustic stimuli in ducklings

Abstract

Filial imprinting is a dedicated learning process that lacks explicit reinforcement. The phenomenon itself is narrowly heritably canalized, but its content, the representation of the parental object, reflects the circumstances of the newborn. Imprinting has recently been shown to be even more subtle and complex than previously envisaged, since ducklings and chicks are now known to select and represent for later generalization abstract conceptual properties of the objects they perceive as neonates, including movement pattern, heterogeneity, and inter-component relationships of same or different. Here we investigate whether day-old Mallard ducklings (Anas platyrhynchos) imprint on the temporal separation between duos of brief acoustic stimuli, and whether they generalize such timing information to novel sound types. Subjects did discriminate temporal structure when imprinted and tested on natural duck calls, but not when using white noise for imprinting or testing. Our data confirm that imprinting includes the establishment of neural representations of both primary percepts and abstract properties of candidate objects, meshing together genetically transmitted prior knowledge with selected perceptual input.