Untrained chimpanzees (Pan troglodytes schweinfurthii) fail to imitate novel actions.

Background: Social learning research in apes has focused on social learning in the technical (problem solving) domain - an approach that confounds action and physical information. Successful subjects in such studies may have been able to perform target actions not as a result of imitation learning but because they had learnt some technical aspect, for example, copying the movements of an apparatus (i.e.

Theft in an ultimatum game: chimpanzees and bonobos are insensitive to unfairness.

Humans, but not chimpanzees, punish unfair offers in ultimatum games, suggesting that fairness concerns evolved sometime after the split between the lineages that gave rise to Homo and Pan. However, nothing is known about fairness concerns in the other Pan species, bonobos. Furthermore, apes do not typically offer food to others, but they do react against theft.

Young children sympathize less in response to unjustified emotional distress.

Three-year-old children saw an adult displaying the exact same distress in 3 different conditions: (a) the adult's distress was appropriate to a genuine harm, (b) the adult's distress was an overreaction to a minor inconvenience, and (c) there was no apparent cause for the adult's distress. Children who witnessed the adult being appropriately upset showed concern for him, intervened on his behalf, and checked on him when he later expressed distress out of their view. Children who did not know the cause for the adult's distress responded similarly.

Twelve-month-olds' comprehension and production of pointing.

This study explored whether infants aged 12 months already recognize the communicative function of pointing gestures. Infants participated in a task requiring them to comprehend an adult's informative pointing gesture to the location of a hidden toy. They mostly succeeded in this task, which required them to infer that the adult was attempting to direct their attention to a location for a reason - because she wanted them to know that a toy was hidden there.

Young children are intrinsically motivated to see others helped.

Young children help other people, but it is not clear why. In the current study, we found that 2-year-old children's sympathetic arousal, as measured by relative changes in pupil dilation, is similar when they themselves help a person and when they see that person being helped by a third party (and sympathetic arousal in both cases is different from that when the person is not being helped at all). These results demonstrate that the intrinsic motivation for young children's helping behavior does not require that they perform the behavior themselves and thus "get credit" for it, but rather requires only that the other person be helped.

Origins of human cooperation and morality.

From an evolutionary perspective, morality is a form of cooperation. Cooperation requires individuals either to suppress their own self-interest or to equate it with that of others. We review recent research on the origins of human morality, both phylogenetic (research with apes) and ontogenetic (research with children).

Young children enforce social norms selectively depending on the violator's group affiliation.

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 enforce social norms on all people equally, or only on ingroup members who presumably know and respect the norm.

Great apes infer others' goals based on context.

In previous studies claiming to demonstrate that great apes understand the goals of others, the apes could potentially have been using subtle behavioral cues present during the test to succeed. In the current studies, we ruled out the use of such cues by making the behavior of the experimenter identical in the test phase of both the experimental and control conditions; the only difference was the preceding "context." In the first study, apes interpreted a human's ambiguous action as having the underlying goal of opening a box, or not, based on that human's previous actions with similar boxes.

Direct and indirect reputation formation in nonhuman great apes (Pan paniscus, Pan troglodytes, Gorilla gorilla, Pongo pygmaeus) and human children (Homo sapiens).

Humans make decisions about when and with whom to cooperate based on their reputations. People either learn about others by direct interaction or by observing third-party interactions or gossip. An important question is whether other animal species, especially our closest living relatives, the nonhuman great apes, also form reputations of others.

Error patterns in young German children's wh-questions.

In this article we report two studies: a detailed longitudinal analysis of errors in wh-questions from six German-learning children (age 2 ; 0-3 ; 0) and an analysis of the prosodic characteristics of wh-questions in German child-directed speech. The results of the first study demonstrate that German-learning children frequently omit the initial wh-word. A lexical analysis of wh-less questions revealed that children are more likely to omit the wh-word was ('what') than other wh-words (e.

Taking versus confronting visual perspectives in preschool children.

Recent evidence suggests that 3-year-olds can take other people's visual perspectives not only when they perceive different things (Level 1) but even when they see the same thing differently (Level 2). One hypothesis is that 3-year-olds are good perspective takers but cannot confront different perspectives on the same object (Perner, Stummer, Sprung, & Doherty, 2002). In 2 studies using color filters, 3-year-olds were unable to judge in what color they and an adult saw the same picture.

Semantics of the transitive construction: prototype effects and developmental comparisons.

This paper investigates whether an abstract linguistic construction shows the kind of prototype effects characteristic of non-linguistic categories, in both adults and young children. Adapting the prototype-plus-distortion methodology of Franks and Bransford (1971), we found that whereas adults were lured toward false-positive recognition of sentences with prototypical transitive semantics, young children showed no such effect. We examined two main implications of the results.

How two word-trained dogs integrate pointing and naming.

Two word-trained dogs were presented with acts of reference in which a human pointed, named objects, or simultaneously did both. The question was whether these dogs would assume co-reference of pointing and naming and thus pick the pointed-to object. Results show that the dogs did indeed assume co-reference of pointing and naming in order to determine the reference of a spoken word, but they did so only when pointing was not in conflict with their previous word knowledge.

Majority-biased transmission in chimpanzees and human children, but not orangutans.

Cultural transmission is a key component of human evolution. Two of humans' closest living relatives, chimpanzees and orangutans, have also been argued to transmit behavioral traditions across generations culturally [1-3], but how much the process might resemble the human process is still in large part unknown. One key phenomenon of human cultural transmission is majority-biased transmission: the increased likelihood for learners to end up not with the most frequent behavior but rather with the behavior demonstrated by most individuals.

Children's ability to answer different types of questions.

Young children answer many questions every day. The extent to which they do this in an adult-like way - following Grice's Maxim of Quantity by providing the requested information, no more no less - has been studied very little. In an experiment, we found that two-, three- and four-year-old children are quite skilled at answering argument-focus questions and predicate-focus questions with intransitives in which their response requires only a single element.

Two- and four-year-olds learn to adapt referring expressions to context: effects of distracters and feedback on referential communication.

Children often refer to things ambiguously but learn not to from responding to clarification requests. We review and explore this learning process here. In Study 1, eighty-four 2- and 4-year-olds were tested for their ability to request stickers from either (a) a small array with one dissimilar distracter or (b) a large array containing similar distracters.

How dogs know when communication is intended for them.

Domestic dogs comprehend human gestural communication in a way that other animal species do not. But little is known about the specific cues they use to determine when human communication is intended for them. In a series of four studies, we confronted both adult dogs and young dog puppies with object choice tasks in which a human indicated one of two opaque cups by either pointing to it or gazing at it.

Dogs (Canis familiaris), but not chimpanzees (Pan troglodytes), understand imperative pointing.

Chimpanzees routinely follow the gaze of humans to outside targets. However, in most studies using object choice they fail to use communicative gestures (e.g.

Collaborative partner or social tool? New evidence for young children's understanding of joint intentions in collaborative activities.

Some children's social activities are structured by joint goals. In previous research, the criterion used to determine this was relatively weak: if the partner stopped interacting, did the child attempt to re-engage her? But re-engagement attempts could easily result from the child simply realizing that she needs the partner to reach her own goal in the activity (social tool explanation). In two experiments, 21- and 27-month-old children interacted with an adult in games in which they either did or did not physically need the partner to reach a concrete goal.

Children's developing commitments to joint goals.

This study investigated young children's commitment to a joint goal by assessing whether peers in collaborative activities continue to collaborate until all received their rewards. Forty-eight 2.5- and 3.

Collaboration in young children.

Humans accomplish much of what they do in collaboration with others. In ontogeny, children's earliest abilities to collaborate develop in two basic steps. First, 1- and 2-year-olds learn to form with others joint goals and joint attention--which include an understanding of the individual roles and perspectives involved.

Methodological challenges in the study of primate cognition.

Laboratory studies of primate cognition face the problem that captive populations of a species are not always comparable, and generalizations to natural populations are never certain. Studies of primate cognition in the field face the problem that replications are expensive and difficult, and again different populations are not always comparable. To help remedy these problems, we recommend the creation of data banks where primary data and videotapes may be deposited (perhaps as a requirement of publication) to facilitate cross-examination, replication, and, eventually, the pooling of data across investigators.

Three-year-olds understand appearance and reality--just not about the same object at the same time.

Young children struggle in the classic tests of appearance versus reality. In the current Study 1, 3-year-olds had to determine which of 2 objects (a deceptive or a nondeceptive one) an adult requested when asking for the "real X" versus "the one that looks like X." In Study 2, children of the same age had to indicate what a single deceptive object (e.

Conformity to peer pressure in preschool children.

Both adults and adolescents often conform their behavior and opinions to peer groups, even when they themselves know better. The current study investigated this phenomenon in 24 groups of 4 children between 4;2 and 4;9 years of age. Children often made their judgments conform to those of 3 peers, who had made obviously erroneous but unanimous public judgments right before them.

A comparison of temperament in nonhuman apes and human infants.

The adaptive behavior of primates, including humans, is often mediated by temperament. Human behavior likely differs from that of other primates in part due to temperament. In the current study we compared the reaction of bonobos, chimpanzees, orangutans, and 2.