We propose that humans are adapted to transfer knowledge to, and receive knowledge from, conspecifics by teaching. This adaptation, which we call 'pedagogy', involves the emergence of a special communication system that does not presuppose either language or high-level theory of mind, but could itself provide a basis facilitating the development of these human-specific abilities both in phylogenetic and ontogenetic terms. We speculate that tool manufacturing and mediated tool use made the evolution of such a new social learning mechanism necessary. However, the main body of evidence supporting this hypothesis comes from developmental psychology. We argue that many central phenomena of human infant social cognition that may seem puzzling in the light of their standard functional explanation can be more coherently and plausibly interpreted as reflecting the adaptations to receive knowledge from social partners through teaching.

Fourteen- and 18-month-old infants observed an adult experiencing each of 2 objects (experienced objects) and then leaving the room; the infant then played with a 3rd object while the adult was gone (unexperienced object). The adult interacted with the 2 experienced objects in 1 of 3 ways: by (a) sharing them with the infant in an episode of joint engagement, (b) actively manipulating and inspecting them on his or her own as the infant watched (individual engagement), or (c) looking at them from a distance as the infant played with them (onlooking). As evidenced in a selection task, infants of both ages knew which objects had been experienced by the adult in the joint engagement condition, only the 18-montholds knew this in the individual engagement condition, and infants at neither age knew this in the onlooking condition. These results suggest that infants are 1st able to determine what adults know (have experienced) on the basis of their direct, triadic engagements with them.

Recent research suggests that chimpanzees are capable of level 1 perspective taking (Flavell, 1992), but that its expression is limited to situations of increased competition (Brauer, Call, & Tomasello, 2007). We present a model utilizing gaze-following that learns in response to the behavior of a competitor. The model not only learns the proper application of the perspective taking strategy but also the critical spatial characteristics that influence the competitive pressure.

Young infants are sensitive to self-directed social actions, but do they appreciate the intentional, target-directed nature of such behaviors? We addressed this question by investigating infants ’ understanding of social gaze in third-party interactions. Tenmonth-old infants discriminated between two people in mutual versus averted gaze, and expected a person to look at her social partner during conversation. In contrast, 9-monthold infants showed neither ability, even when provided with information that highlighted the gazer’s social goals. These results indicate considerable improvement in infants’ abilities to analyze the social gaze of others towards the end of their first year, which may relate to their appreciation of gaze as both a social and goal-directed action. Running head: INFANTS ’ DEVELOPING UNDERSTANDING OF SOCIAL GAZE 3 Infants ’ Developing Understanding of Social Gaze Eye gaze is a central element of human social interaction that can reflect a person's feelings, her attitudes towards a social partner, and her goals for their interaction (Kleinke, 1986). Within an interaction, social partners attend to each other’s gaze and use gaze to regulate both the immediate sequence of their exchange (Kendon, 1967) and

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Young infants are sensitive to self-directed social actions, but do they appreciate the intentional, target-directed nature of such behaviors? The authors addressed this question by investigating infants ’ understanding of social gaze in third-party interactions (N = 104). Ten-month-old infants discriminated between 2 people in mutual versus averted gaze, and expected a person to look at her social partner during conversation. In contrast, 9-month-old infants showed neither ability, even when provided with information that highlighted the gazer’s social goals. These results indicate considerable improvement in infants ’ abilities to analyze the social gaze of others toward the end of their 1st year, which may relate to their appreciation of gaze as both a social and goal-directed action. We are grateful to the infants and families who participated. This research was funded by NSF GRF DGE-0644491 to J.S.B.

Previous research has found that young children recognize an adult as being acquainted with an object most readily when the child and adult have previously engaged socially with that object together. In the current study, we tested the hypothesis that such social engagement is so powerful that it can sometimes lead children to overestimate what has been shared. After having shared two objects with an adult in turn, 2-year-old children played with a third object the adult could not see. In three out of four conditions, the adult remained co-present and ⁄ or communicated to the child while she played with the third object. Children falsely perceived the adult as being acquainted with the third object when she remained co-present (whether or not she also communicated) but not when she clearly terminated the interaction by disengaging and leaving. These results suggest that when young children are engaged with a co-present person they tend to overestimate the other’s knowledge. For humans to interact appropriately with each other and arrive at some mutual understanding, they need to know what others perceive and know. Developmental research indicates that even infants possess some understanding in both of these domains. They begin to understand some basic things about seeing in the first half year of their lives, when they turn their head in the same direction another person has just looked (D’Entremont,