Anthony D. Pellegrini’s research while affiliated with University of Minnesota, Duluth and other places

The ways in which objects were used by preschool children (Homo sapiens) was examined by directly observing them across one school year. In the first objective we documented the relative occurrence of different forms of object use and their developmental growth curves. Second, we examined the role of different types of object use, as well as novel and varied uses of objects, in predicting peer group centrality. Results indicated that noninstrumental object play was the most frequently observed category, followed by tool use, exploration, and construction; sex moderated the growth curve of children's exploration. Noninstrumental object play, not other types of object use, was significantly related to novel and varied object uses and only the latter category predicted peer group centrality. Results are discussed in terms of the social transmission of novel object use.

This longitudinal, naturalistic study addressed behavioral and social cognitive processes implicated in preschool children's social dominance. In the first objective, we examined the degree to which peer aggression, affiliation, and postaggression reconciliation predicted social dominance across a school year. Consistent with predictions, all three predicted dominance early in the year while only affiliation predicted dominance later in the year, suggesting that aggression, affiliation, and reconciliation were used to establish social dominance where affiliation was used to maintain it. In the second, exploratory, objective we tested the relative importance of social dominance and reconciliation (the Machiavellian and Vygotskian intelligence hypotheses, respectively) in predicting theory of mind/false belief. Results indicated that social dominance accounted for significant variance, beyond that related to reconciliation and affiliation, in predicting theory of mind/false belief status. Results are discussed in terms of specific behavioral and social cognitive processes employed in establishing and maintaining social dominance.

Evolutionary PsychologyEvolutionary Developmental PsychologyTopics in Social Development From an Evolutionary PerspectiveEvolution and Social DevelopmentReferences

Observational studies of breakfast frequency in children and adults suggest an inverse (protective) association between the frequency of eating breakfast and the risk for obesity and chronic diseases such as type 2 diabetes. More prospective studies with stronger designs are needed, as are experimental studies on this topic. In addition, above and beyond breakfast frequency, the roles of dietary quality and composition need to be studied in the context of eating or skipping breakfast. Experimental studies are also necessary to rigorously test causality and biological mechanisms. Therefore, we conducted 2 pilot experimental studies to examine some of the effects of breakfast skipping and breakfast composition on blood glucose and appetite in children and adults. Our results suggest that breakfast frequency and quality may be related in causal ways to appetite controls and blood sugar control, supporting the hypothesis that the breakfast meal and its quality may have important causal implications for the risk of obesity and type 2 diabetes.

Bullying and victimization were studied from a longitudinal, multi-method, multi-agent perspective as youngsters made the transition from primary through middle school. Generally, bullying and aggression increased with the transition to middle school and then declined. Bullying mediated youngsters' dominance status during the transition. Bullying may be one way in which young adolescents manage peer and dominance relationships as they make the transition into new social groups. Victimization declined from primary to secondary school. Correspondingly, youngsters' peer affiliations decreased, initially with the transition, and then recovered. Victimization, however, was buffered by peer affiliation, especially like most nominations relative to friendship nominations, during this time. Additionally, and consistent with the idea that bullying is used for dominance displays, cross-sex comparisons of aggressive bouts indicated that boys targeted other boys and did not target girls. Results are discussed in terms of the changing functions of aggression during adolescence.

Sex segregation during the juvenile period is a pan-cultural phenomenon in humans as well as being observed in many other vertebrate species. In this paper I define sex segregation in human and nonhuman animals and chart its ontogeny in humans from childhood through early adolescence. Second, I argue that sexual selection theory can explain segregation in humans. Third and consistent with this theory I posit that sexual selection effects on segregation are moderated by proximal factors, such as individual differences in activity and ecological factors. Fourth, I suggest possible functions of sex segregation in humans. Lastly and in conclusion, I discuss methodological issues that need addressing in the study of human sex segregation.

Sex differences in adults' observations and ratings of children's aggression was studied in a sample of preschool children (N=89, mean age=44.00months, SD=8.48). When examining the direct observations made by trained observers, male observers, relative to female observers, more frequently recorded aggressive bouts, especially of boys. On rating scales assessing aggression, trained male raters also gave higher aggressive ratings than female raters. Lastly, we compared the ratings of trained female raters and female teachers on the same scale and found no differences. Results are discussed in terms male raters' and observers' prior experiences in activating their experiential schemata where males' greater experience in aggression, relative to that of females, leads them to perceive greater levels of aggression.

In discussing the importance of computer games for conveying serious messages through play, Aleks Krotoski uses “play” and “games” interchangeably (Nature 466, 695; 2010). However, this is incorrect in the context of human development: these terms denote separate constructs, with different ontogenies, proximal causes and functions. Play is mainly a behaviour…

In this 2-year longitudinal study, we hypothesized that sex of the human child (Homo sapiens), differences in physical activity, and time of the year would interact to influence preschool children's sex segregation. We also hypothesized that activity would differentially relate to peer rejection for boys and girls. Consistent with the first hypothesis, high-activity girls started off as the most integrated group but became more segregated with time, whereas high-activity boys remained the most segregated group across the duration of the study. The second hypothesis was also supported: For girls only, activity was significantly related to peer rejection during Year 1 only, the time when high-activity girls also interacted frequently with boys. Results are discussed in terms of sexual selection theory and gender boundary violations.

Bistrategic resource control entails using both coercive and prosocial strategies in competition for resources. The present study sought to clarify whether bistrategic involves more than simply using both strategies some of the time. Examining 88 preschoolers' coercion and prosociality over an entire school year, results showed that coercive resource control was used most frequently at the start of the school year, presumably to access resources and establish social dominance. Rates of prosocial resource control increased over the school year, and socially dominant preschoolers showed higher rates compared with peers, presumably to maintain resource control while keeping peers as allies. Socially dominant preschoolers also used reconciliation more often than peers, resulting in higher rates of affiliation between former competitors and more positive peer regard from fall to spring. Findings are discussed in terms of resource control theory and the importance of situating social behaviors within the behavioral and relationship context in which they are embedded.