Context learning before birth: evidence from the chick embryo.

Learning contextual information to form associative memories with stimuli of interest is an important brain function in both human and non-human animals. Intuitively, one would expect that such a sophisticated cognitive skill develops postnatally, as the organism starts exploring the surrounding environment to search for significant contingencies among stimuli. Here we show, instead, that even before hatching, domestic chicks are capable of forming associative memories between discrete alerting sounds and the surrounding context, as attested by the fact that habituation of the freezing response to the sounds is affected by the context of stimulation. This finding indicates that, while in the egg, chicks recognize and learn the context in which they are stimulated. Hence, context learning in chicks is an innate brain function already active before birth, which can provide an immediate survival advantage to the newborns of this precocial avian species.