Shared intentionality theory posits that at age 3, children expand their conception of plural agency to include 3- or more-person groups. We sought to determine whether this conceptual shift is detectable in children's pronoun use. We report the results of a series of Bayesian hierarchical generative models fitted to 479 English-speaking…

The current study aimed to investigate the cultural differences in the developmental origins of children's intent-based moral judgment and moral behavior in the context of indirect reciprocity. To this end, we compared how German and Chinese children interpret and react to antisocial and prosocial interactions between puppets. An actor puppet…

Much research has investigated how children relate to norms taught to them by adult authorities. Very few studies have investigated norms that arise out of children's own peer interactions. In two studies, we investigated how 5- and 7-year-old children teach, enforce, and understand rules that they either created themselves or were taught by an…

This study investigated how great apes and human infants use imperative pointing to request objects. In a series of three experiments (infants, N = 44; apes, N = 12), subjects were given the opportunity to either point to a desired object from a distance or else to approach closer and request it proximally. The apes always approached close to the…

Human beings have remarkable skills of self-control, but the evolutionary origins of these skills are unknown. Here we compare children at 3 and 6 years of age with one of humans' two nearest relatives, chimpanzees, on a battery of reactivity and self-control tasks. Three-year-old children and chimpanzees were very similar in their abilities to…

This study investigates how children negotiate social norms with peers. In Study 1, 48 pairs of 3- and 5-year-olds (N = 96) and in Study 2, 48 pairs of 5- and 7-year-olds (N = 96) were presented with sorting tasks with conflicting instructions (one child by color, the other by shape) or identical instructions. Three-year-olds differed from older…

Both chimpanzees and human infants use the pointing gesture with human adults, but it is not clear if they are doing so for the same social motives. In two studies, we presented chimpanzees and human 25-month-olds with the opportunity to point for a hidden tool (in the presence of a non-functional distractor). In one condition it was clear that…

We compared the performance of 3- and 5-year-old children with that of chimpanzees in two tasks requiring collaboration via complementary roles. In both tasks, children and chimpanzees were able to coordinate two complementary roles with peers and solve the problem cooperatively. This is the first experimental demonstration of the coordination of…

A milestone in human development is coming to recognize that how something looks is not necessarily how it is. We tested appearance-reality understanding in chimpanzees ("Pan troglodytes") with a task requiring them to choose between a small grape and a big grape. The apparent relative size of the grapes was reversed using magnifying and…

There is currently much controversy about which, if any, mental states chimpanzees and other nonhuman primates understand. In the current two studies we tested both chimpanzees' and human children's understanding of both knowledge-ignorance and false belief--in the same experimental paradigm involving competition with a conspecific. We found that…

It has been repeatedly shown that when asked to identify a protagonist's false belief on the basis of his false statement, English-speaking 3-year-olds dismiss the statement and fail to attribute to him a false belief. In the present studies, we tested 3-year-old Japanese children in a similar task, using false statements accompanied by…

The current study investigated the influence of rewards on very young children's helping behavior. After 20-month-old infants received a material reward during a treatment phase, they subsequently were less likely to engage in further helping during a test phase as compared with infants who had previously received social praise or no reward at…

Helping and cooperation are central to human social life. Here, we report two studies investigating these social behaviors in children with autism and children with developmental delay. In the first study, both groups of children helped the experimenter attain her goals. In the second study, both groups of children cooperated with an adult, but…

Using a preferential looking methodology with novel verbs, Gertner, Fisher and Eisengart (2006 ) found that 21-month-old English children seemed to understand the syntactic marking of transitive word order in an abstract, verb-general way. In the current study we tested whether young German children of this same age have this same understanding.…

There is little experimental evidence that any non-human species is capable of purposefully attempting to manipulate the psychological states of others deceptively (e.g., manipulating what another sees). We show here that chimpanzees, one of humans' two closest primate relatives, sometimes attempt to actively conceal things from others.…