DEVELOPMENT OF SPECIES IDENTIFICATION IN DUCKLINGS .5. PERCEPTUAL DIFFERENTIATION IN THE EMBRYO

Studied the precise manner in which normally occurring exposure to embryonic vocalization contributes to the Peking duckling's ability to detect distinctive features of the maternal call. Polygraphic recordings of heartbeat, bill-clapping, and vocalization were made from embryos that were exposed to maternal calls or were incubated in silence. The key acoustic features of the maternal call for the embryo were high- and low-frequency components and repetition rate. Embryonic auditory experience facilitated the development of high-frequency sensitivity, whereas it maintained repetition-rate specificity. The single most important finding was that the embryo's initial perceptual response to the maternal call was not fully differentiated in advance of exposure to its own or sib vocalizations. The youngest (Day 22) aurally inexperienced embryo's behavioral response to the maternal call was based on only the low-frequency components, whereas the aurally experienced Day 22 embryo's response was based on both high- and low-frequency components. Although the initial repetition-rate specificity of the Day 22 embryos was as sharp without auditory experience as it was with it, subsequent development on this perceptual dimension, if it is to be species-typical, requires auditory experience. (30 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1979 American Psychological Association.