Abstract: At around 1 year of age, human infants display a number of new behaviors that seem to indicate a newly emerging understanding of other persons as intentional beings whose attention to outside objects may be shared, followed into, and directed in various ways. These behaviors have mostly been studied separately. In the current study, we investigated the most important of these behaviors together as they emerged in a single group of 24 infants between 9 and 15 months of age. At each of seven monthly visits, we measured joint attentional engagement, gaze and point following, imitation of two different kinds of actions on objects, imperative and declarative gestures, and comprehension and production of language. We also measured several nonsocial-cognitive skills as a point of comparison. We report two studies. The focus of the first study was the initial emergence of infants' social-cognitive skills and how these skills are related to one another developmentally. We found a reliable pattern of emergence: Infants progressed from sharing to following to directing others' attention and behavior. The nonsocial skills did not emerge predictably in this developmental sequence. Furthermore, correlational analyses showed that the ages of emergence of all pairs of the social-cognitive skills or their components were interrelated. The focus of the second study was the social interaction of infants and their mothers, especially with regard to their skills of joint attentional engagement (including mothers' use of language to follow into or direct infants' attention) and how these skills related to infants' early communicative competence. Our measures of communicative competence included not only language production, as in previous studies, but also language comprehension and gesture production. It was found that two measures-the amount of time infants spent in joint engagement with their mothers and the degree to which mothers used language that followed into their infant's focus of attention-predicted infants' earliest skills of gestural and linguistic communication. Results of the two studies are discussed in terms of their implications for theories of social-cognitive development, for theories of language development, and for theories of the process by means of which human children become fully participating members of the cultural activities and processes into which they are born.

Abstract: Dogs are more skillful than great apes at a number of tasks in which they must read human communicative signals indicating the location of hidden food. In this study, we found that wolves who were raised by humans do not show these same skills, whereas domestic dog puppies only a few weeks old, even those that have had little human contact, do show these skills. These findings suggest that during the process of domestication, dogs have been selected for a set of social-cognitive abilities that enable them to communicate with humans in unique ways.

Abstract: We conducted three experiments on social problem solving by chimpanzees, Pan troglodytes. In each experiment a subordinate and a dominant individual competed for food, which was placed in various ways on the subordinate's side of two opaque barriers. In some conditions dominants had not seen the food hidden, or food they had seen hidden was moved elsewhere when they were not watching (whereas in control conditions they saw the food being hidden or moved). At the same time, subordinates always saw the entire baiting procedure and could monitor the visual access of their dominant competitor as well. If subordinates were sensitive to what dominants did or did not see during baiting, they should have preferentially approached and retrieved the food that dominants had not seen hidden or moved. This is what they did in experiment 1 when dominants were either uninformed or misinformed about the food's location. In experiment 2 subordinates recognized, and adjusted their behaviour accordingly, when the dominant individual who witnessed the hiding was replaced with another dominant individual who had not witnessed it, thus demonstrating their ability to keep track of precisely who has witnessed what. In experiment 3 subordinates did not choose consistently between two pieces of hidden food, one of which dominants had seen hidden and one of which they had not seen hidden. However, their failure in this experiment was likely to be due to the changed nature of the competition under these circumstances and not to a failure of social-cognitive skills. These findings suggest that at least in some situations (i.e. competition with conspecifics) chimpanzees know what conspecifics have and have not seen (do and do not know), and that they use this information to devise effective social-cognitive strategies. Copyright 2001 The Association for the Study of Animal Behaviour.

Abstract: Domestic dogs are unusually skilled at reading human social and communicative behavior--even more so than our nearest primate relatives. For example, they use human social and communicative behavior (e.g. a pointing gesture) to find hidden food, and they know what the human can and cannot see in various situations. Recent comparisons between canid species suggest that these unusual social skills have a heritable component and initially evolved during domestication as a result of selection on systems mediating fear and aggression towards humans. Differences in chimpanzee and human temperament suggest that a similar process may have been an important catalyst leading to the evolution of unusual social skills in our own species. The study of convergent evolution provides an exciting opportunity to gain further insights into the evolutionary processes leading to human-like forms of cooperation and communication.

Abstract: Ten domestic dogs (Canis familiaris) of different breeds and ages were exposed to 2 different social cues indicating the location of hidden food, each provided by both a human informant and a conspecific informant (for a total of 4 different social cues). For the local enhancement cue, the informant approached the location where food was hidden and then stayed beside it. For the gaze and point cue, the informant stood equidistant between 2 hiding locations and bodily oriented and gazed toward the 1 in which food was hidden (the human informant also pointed). Eight of the 10 subjects, including the one 6-month-old juvenile, were above chance with 2 or more cues. Results are discussed in terms of the phylogenetic and ontogenetic processes by means of which dogs come to use social cues to locate food.