Experiential canalization of behavioral development: Theory.

In exploring the possible experiential canalization of development, it was found that the mallard duck embryos contact call plays a canalizing role in species-specific perceptual development. When mallard ducklings were prevented from hearing the contact call, they were susceptible to developing a preference for an extraspecific maternal call over the mallard maternal call. Exposure to the contact call prevented the ducklings from developing a preference for the extraspecific maternal call. Thus, normally occurring experience, in concert with genetic and other activities, can canalize behavioral development. Canalizing influences account for developmental stability, so that what we think of as normal or typical for a species repeats itself generation after generation. In order for evolution to occur, through genetic mutation or otherwise, the canalizing influences associated with normal development must be overcome. Canalization is thus a conservative feature of development that prevents evolution from occurring in a ready fashion. My preceding article (Gottlieb, 1991 a) established the theoretical framework for examining the possibility that normally occurring experience can canalize behavioral development. The present article presents empirical evidence for the experiential