To become cooperative members of their cultural groups, developing children must follow their group's social norms. But young children are not just blind norm followers, they are also active norm enforcers, for example, protesting and correcting when someone plays a conventional game the "wrong" way. In two studies, we asked whether young children…

The present work investigated young children's normative understanding of property rights using a novel methodology. Two- and 3-year-old children participated in situations in which an actor (1) took possession of an object for himself, and (2) attempted to throw it away. What varied was who owned the object: the actor himself, the child subject,…

Young children use and comprehend different kinds of speech acts from the beginning of their communicative development. But it is not clear how they understand the conventional and normative structure of such speech acts. In particular, imperative speech acts have a world-to-word direction of fit, such that their fulfillment means that the world…

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…

Many studies have established that children tend to exclude objects for which they already have a name as potential referents of novel words. In the current study we asked whether this exclusion can be triggered by social-pragmatic context alone without pre-existing words as blockers. Two-year-old children watched an adult looking at a novel…

Recently, several studies have claimed that soon after their first birthday infants understand others' false beliefs. However, some have questioned these findings based on criticisms of the looking-time paradigms used. Here we report a new paradigm to test false belief understanding in infants using a more active behavioral response: helping.…

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…

In the current study we investigated whether 12-month-old infants gesture appropriately for knowledgeable versus ignorant partners, in order to provide them with needed information. In two experiments we found that in response to a searching adult, 12-month-olds pointed more often to an object whose location the adult did not know and thus needed…

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.…

Recent studies have established that even infants can determine what others know based on previous visual experience. In the current study, we investigated whether 2-and 3-year-olds know what others know based on previous auditory experience. A child and an adult heard the sound of one object together, but only the child heard the sound of another…

Previous research has reported that bilingual children sometimes produce mixed noun phrases with "correct" gender agreement--as in "der dog" ("der" being a masculine determiner in German and the German word for "dog", "hund", being masculine as well). However, these could obviously be due to chance or to the indiscriminate use of a default…

Presents evidence that the supposed paradox in which infants find abstract patterns in speech-like stimuli whereas even some preschoolers struggle to find abstract syntactic patterns within meaningful language is no paradox. Asserts that all research evidence shows that young children's syntactic constructions become abstract in a piecemeal…

Details findings indicating that most early linguistic competence is item based. Maintains that language development proceeds without evidence of system-wide syntactic categories, schemas, or parameters. Suggests that findings are not easily explained by the development of children's skills of linguistic performance, pragmatics, or other external…

Classically, infants are thought to point for 2 main reasons: (a) They point imperatively when they want an adult to do something for them (e.g., give them something; "Juice!"), and (b) they point declaratively when they want an adult to share attention with them to some interesting event or object ("Look!"). Here we demonstrate the existence of…

In the studies presented here, infants' understanding of others' attention was assessed when gaze direction cues were not diagnostic. Fourteen-, 18- and 24-month-olds witnessed an adult look to the side of an object and express excitement. In 1 experimental condition this object was new for the adult because she was not present while the child and…