Social category formation is induced by cues of sharing knowledge in young children.

Previous research has shown that human infants and young children are sensitive to the boundaries of certain social groups, which supports the idea that the capacity to represent social categories constitutes a fundamental characteristic of the human cognitive system. However, the function this capacity serves is still debated. We propose that during social categorization the human mind aims at mapping out social groups defined by a certain set of shared knowledge. An eye-tracking paradigm was designed to test whether two-year-old children differentially associate conventional versus non-conventional tool use with language-use, reflecting an organization of information that is induced by cues of shared knowledge. Children first watched videos depicting a male model perform goal-directed actions either in a conventional or in a non-conventional way. In the test phase children were presented with photographs taken of the model and of a similarly aged unfamiliar person while listening to a foreign (Experiment 1) or a native language (Experiment 2) text. Upon hearing the foreign utterance children looked at the model first if he had been seen to act in an unconventional way during familiarization. In contrast, children looked at the other person if the model had performed conventional tool use actions. No such differences were found in case of the native language. The results suggest that children take the conventionality of behavior into account in forming representations about a person, and they generalize to other qualities of the person based on this information