Many research findings about animal play apply to children's play, revealing structural and functional similarities with mammals in general and primates in particular. After an introduction to life-history theory, and before turning to humans, the author reviews research about the two mammals in which play has been studied the most extensively:…

To date, the majority of research on Attention-Deficit/Hyperactivity Disorder (ADHD) has been completed with boys as the predominate participants in study samples. Over the past decade there has been increased attention focused on the characteristics and needs of girls with ADHD. Although much of the research comparing boys and girls with ADHD…

In this article, the authors describe recent research on peer victimization and its mental health consequences during early adolescence. They begin with a working definition of peer victimization that distinguishes it from lethal school violence and from simple conflict between peers. They then present a psychosocial profile of youth who are…

This study examined how parents influence sex differences in young children's physical risk taking behaviors. Eighty three- and four-year old, mostly middle class and Caucasian children climbed across a five-foot high catwalk and walked across a three-foot high beam under their mother or father's supervision. Based on average preschooler gross…

Research indicates that maladaptive patterns of Internet use constitute behavioral addiction. This article explores the research on the social effects of Internet addiction. There are four major sections. The Introduction section overviews the field and introduces definitions, terminology, and assessments. The second section reviews research…

In an Internet study unrelated to handedness, 134,317 female and 120,783 male participants answered a graded question as to which hand they preferred for writing. This allowed determination of hand preference patterns across 7 ethnic groups. Sex differences in left-handedness were found in 4 ethnic groups, favoring males, while no significant sex…

I use the introduction of a competitive fellowship program for graduate students to test whether men and women respond differently to competition and whether this response depends on the gender mix of the group. Men experienced a 10% increase in performance in response to the program, with the largest gains for men in departments with the most…