Human cognition is founded, in part, on four systems for representing objects, actions, number, and space. It may be based, as well, on a fifth system for representing social partners. Each system has deep roots in human phylogeny and ontogeny, and it guides and shapes the mental lives of adults. Converging research on human infants, non-human primates, children and adults in diverse cultures can aid both understanding of these systems and attempts to overcome their limits.

What leads humans to divide the social world into groups, preferring their own group and disfavoring others? Experiments with infants and young children suggest these tendencies are based on predispositions that emerge early in life and depend, in part, on natural language. Young infants prefer to look at a person who previously spoke their native language. Older infants preferentially accept toys from native-language speakers, and preschool children preferentially select native-language speakers as friends. Variations in accent are sufficient to evoke these social preferences, which are observed in infants before they produce or comprehend speech and are exhibited by children even when they comprehend the foreign-accented speech. Early-developing preferences for native-language speakers may serve as a foundation for later-developing preferences and conflicts among social groups. cognitive developmentThe Gileadites captured the fords of the Jordan leading to Ephraim, and whenever a survivour of Ephraim said, ''Let me go over,'' the men of Gilead asked him, ''Are you an Ephraimite?'' If he replied, ''No,'' they said, ''All right, say 'Shibboleth'.'' If he said, ''Sibboleth,'' because he could not pronounce the word correctly, they seized him and killed him at the fords of the Jordan. Forty-two thousand Ephraimites were killed at that time.Judges 12:5-6. The biblical story of Shibboleth speaks of the ancient massacre of those who could not correctly pronounce a phrase, thereby revealing their out-group status. Modern-day Shibboleth is ubiquitous: United States history alone abounds with examples of linguistic discrimination, from the severing of the tongues of slaves who spoke no English, to the forbidding of the public speaking of German during World War II and the execution of Russian speakers after the Alaskan purchase (1). Recent world history provides examples of linguicide paired with genocide of the Kurds in Turkey (2) and of imposed language policies initiating antiApartheid riots in South Africa (3). Favor for one's native language group pervades contemporary politics in more subtle ways as well, for example, in recent debates concerning bilingual education, the politics of sign languages in deaf education, or proposals to make English the national language of the United States. We present evidence that the connection between language and human social groups has roots in human infancy, where it guides early-developing social preferences and predisposes humans to interact with members of their own linguistic group.Newborn infants are sensitive to human speech and prefer the sound of their mother's voice and their native language (4-8).Throughout the first year of life, an ability to distinguish contrasts between nonnative speech sounds diminishes, whereas sensitivity to native speech is maintained (9-11). Although infants' looking time preferences to familiar vs. novel displays may vary based on factors such as complexity and duration of exposure (12)(13)(14)(15), often young infants demonstrate a preferen...

A series of experiments investigated the effect of speakers’ language, accent, and race on children’s social preferences. When presented with photographs and voice recordings of novel children, 5-year-old children chose to be friends with native speakers of their native language rather than foreign-language or foreign-accented speakers. These preferences were not exclusively due to the intelligibility of the speech, as children found the accented speech to be comprehensible, and did not make social distinctions between foreign-accented and foreign-language speakers. Finally, children chose same-race children as friends when the target children were silent, but they chose other-race children with a native accent when accent was pitted against race. A control experiment provided evidence that children’s privileging of accent over race was not due to the relative familiarity of each dimension. The results, discussed in an evolutionary framework, suggest that children preferentially evaluate others along dimensions that distinguished social groups in prehistoric human societies.

Whether emotion is a source of moral judgments remains controversial. This study combined neurophysiological measures, including functional magnetic resonance imaging, eye-tracking, and pupillary response with behavioral measures assessing affective and moral judgments across age. One hundred and twenty-six participants aged between 4 and 37 years viewed scenarios depicting intentional versus accidental actions that caused harm/damage to people and objects. Morally, salient scenarios evoked stronger empathic sadness in young participants and were associated with enhanced activity in the amygdala, insula, and temporal poles. While intentional harm was evaluated as equally wrong across all participants, ratings of deserved punishments and malevolent intent gradually became more differentiated with age. Furthermore, age-related increase in activity was detected in the ventromedial prefrontal cortex in response to intentional harm to people, as well as increased functional connectivity between this region and the amygdala. Our study provides evidence that moral reasoning involves a complex integration between affective and cognitive processes that gradually changes with age and can be viewed in dynamic transaction across the course of ontogenesis. The findings support the view that negative emotion alerts the individual to the moral salience of a situation by bringing discomfort and thus can serve as an antecedent to moral judgment.

Across two experiments, preschool-aged children demonstrated selective learning of non-linguistic information from native-accented rather than foreign-accented speakers. In Experiment 1, children saw videos of a native- and a foreign-accented speaker of English who each spoke for 10 seconds, and then silently demonstrated different functions with novel objects. Children selectively endorsed the silent object function provided by the native-accented speaker. In Experiment 2, children again endorsed the native-accented over the foreign-accented speaker, even though both informants previously spoke only in nonsense speech. Thus, young children demonstrate selective trust in native-accented speakers even when neither informant's speech relays meaningful semantic content, and the information that both informants provide is non-linguistic. We propose that children orient towards members of their native community to guide their early cultural learning.

Group-based social hierarchies exist in nearly every society, yet little is known about whether children understand that they exist. The present studies investigated whether 3- to 10-year-old children (N=84) in South Africa associate higher-status racial groups with higher levels of wealth, one indicator of social status. Children matched higher-value belongings with White people more often than with multiracial or Black people and with multiracial people more often than with Black people, thus showing sensitivity to the de facto racial hierarchy in their society. There were no age-related changes in children’s tendency to associate racial groups with wealth differences. The implications of these results are discussed in light of the general tendency for people to legitimize and perpetuate the status quo.

Across four studies, we directly compared children's essentialist reasoning about the stability of race and language throughout an individual's lifespan. Monolingual English-speaking children were presented with a series of images of children who were either White or Black; each face was paired with a voice clip in either English or French. Participants were asked which of two adults each target child would grow up to be - one who was a 'match' to the target child in race but not language, and the other a 'match' in language but not race. Nine- to 10-year-old European American children chose the race-match, rather than the language-match. In contrast, 5-6-year-old European American children in both urban, racially diverse, and rural, racially homogeneous environments chose the language-match, even though this necessarily meant that the target child would transform racial categories. Although surprising in light of adult reasoning, these young children demonstrated an intuition about the relative stability of an individual's language compared to her racial group membership. Yet, 5-6-year-old African American children, similar to the older European American children, chose the race-match, suggesting that membership in a racial minority group may highlight children's reasoning about race as a stable category. Theoretical implications for our understanding of children's categorization of human kinds are discussed.

Behavioral research indicates that human females are more empathic than males, a disparity that widens from childhood to adulthood. Nevertheless, the extent to which such sex differences are an artifact of self-report indices is unclear. The present study compared age-related sex differences in both self-report and neurophysiological measures of empathic arousal, a primary building block of empathy. Participants included sixty-five 4-17-year-old children (mean 11.5±3.5 years) who completed the Bryant Empathy Scale, and were scanned while viewing animated clips depicting people being hurt. Female participants scored higher than males on self-reported dispositional empathy, a difference that increased with age. In contrast, no sex-related differential changes were detected in hemodynamic responses or in pupil dilation, with no interaction between sex and age. Results suggest a dissociation between explicit ratings and neurophysiological measures of empathic arousal. Past observed sex differences in empathy may reflect females' greater willingness to report empathic experiences. Findings are also discussed in terms of discrepancies in the methods used to assess affective responding and how they relate to the multi-faceted construct of empathy.