From early in life, infants synchronize with others on a physiological level, a process thought to underlie social connections and group cohesion. This synchronization is seen, for example, when their pupils dilate in response to observing another person with dilated pupils -- known as "pupillary contagion." There is mixed evidence on…

Fourteen-month-olds selectively imitated a sub-efficient means (illuminating a lightbox by a head-touch) when this was modeled by linguistic ingroup members in video-demonstrations. A follow-up study with slightly older infants, however, could replicate this effect only in a video-demonstration context. Hence it still remains unclear whether…

In 4 experiments, we examined 16- and 20-month-old infants' understanding of proper names and count nouns. In each experiment, infants were taught a novel word modeled linguistically as either a proper name (e.g., "DAXY") or a count noun (e.g., "a DAXY") for a stuffed animal shown on a puppet stage. This animal was moved to a new location on the…