In Study 1, 4-year-olds avoided 2 names for an object when exposed to a common or a proper noun in a puppet's presence or to a common noun in a puppet's absence, but not when exposed to a proper noun in a puppet's absence. In Study 2, 3-year-olds avoided 2 names for an object when the requester for the referent of a second label in a different…

Six schools were randomly assigned to a multilevel bullying intervention or a control condition. Children in Grades 3-6 (N=1,023) completed pre- and posttest surveys of behaviors and beliefs and were rated by teachers. Observers coded playground behavior of a random subsample (n=544). Hierarchical analyses of changes in playground behavior…

Three experiments document that conceptual knowledge influences lexical acquisition in infancy. A novel target object was initially labeled with a novel word. In both yes-no (Experiment 1) and forced-choice (Experiment 2) tasks, 2-year-olds' subsequent extensions were mediated by the conceptual description of the targets. When targets were…

Although conscience has been the focus of reflection for centuries, fundamental questions regarding its organization have not been fully answered. To address those questions, the authors applied structural equation modeling techniques to longitudinal data comprising multiple behavioral measures of children's conscience, obtained in parallel…

Sex differences in play are apparent in a number of mammalian species, including humans. Prenatal testosterone may contribute to these differences. The authors report the first attempt to correlate gender-typed play in a normative sample of humans with measurements of amniotic testosterone (aT). Testosterone was measured in the amniotic fluid of…

The authors investigated the role of syntax in verb learning in Mandarin Chinese, which allows pervasive ellipsis of noun arguments. Two questions were investigated using the Beijing corpus on CHILDES: (a) Does the input to young children manifest syntactic-semantic correspondences as needed for acquiring verb meanings? (b) Are verbs presented in…

This study examined the development of infants' ability to perceive, learn, and remember the unique face-voice relations of unfamiliar adults. Infants of 2, 4, and 6 months were habituated to the faces and voices of 2 same-gender adults speaking and then received test trials where the faces and voices were synchronized yet mismatched. Results…

Life history theory provided a framework for examining the relations among child sexual abuse (CSA), childhood adversity, and patterns of reproductive development and behavior. A community survey that assessed CSA, life history variables (e.g., age of menarche), and social and family background was administered to 623 women (mean age=26.9 years).…

Two experiments on preschoolers' understanding of the effects of exposure on knowing-that and knowing-how were conducted with 3-, 4-, and 5-year-old children (N=388) in 2 locations: a small midwestern city in the United States and a suburban area of Hong Kong, China. By using both English- and Chinese-speaking samples, the authors examined…

This study investigated the effects of familiarization and attention on event-related potential (ERP) correlates of recognition memory in infants. Infants 4.5, 6, or 7.5 months of age were either familiarized with 2 stimuli that were used during later testing or presented 2 stimuli that were not used later. Then, infants were presented with a…

A comparative developmental framework was used to determine whether mutual gaze is unique to humans and, if not, whether common mechanisms support the development of mutual gaze in chimpanzees and humans. Mother-infant chimpanzees engaged in approximately 17 instances of mutual gaze per hour. Mutual gaze occurred in positive, nonagonistic…

In this study, 306 individuals in 3 age groups--adolescents (13-16), youths (18-22), and adults (24 and older)--completed 2 questionnaire measures assessing risk preference and risky decision making, and 1 behavioral task measuring risk taking. Participants in each age group were randomly assigned to complete the measures either alone or with 2…

Children's assessment of the value of different sources of information about psychological traits was investigated among 6- to 7-year-olds and 10- to 11-year-olds across 5 studies (N=330). Older children were more likely than younger children to reject self-report as a source of information about the highly evaluative traits smart and honest, but…

The authors studied receptive cooperation--a willing, eager stance toward parents--in 15-month-old children (N=101) in broadly ranging contexts. Children's anger proneness and parents' responsiveness (both observed at 7 months) and children's attachment security (assessed in Strange Situation at 15 months) were examined as predictors of children's…

The authors investigated age-related changes in executive control using an Internet-based task-switching experiment with 5,271 participants between the ages of 10 and 66 years. Speeded face categorization was required on the basis of gender (G) or emotion (E) in single task blocks (GGG... and EEE...) or switching blocks (GGEEGGEE...). General…