Discusses the history of developmental psychopathology and indicates reasons the discipline emerged as a separate area of study during the last decade. (RH)

The ethological hypothesis that "parental" caregiving can be elicited by certain physical characteristics of infants was investigated in three experiments. Results demonstrated that age-related changes in physical appearance can alter the verbally reported tendency to protect or cuddle others. (Author/RH)

This study examines frequency, overlap, and genetic and environmental influences on sleep difficulties, which are understudied in school-aged children. The Sleep Self Report and the Children's Sleep Habits Questionnaire were completed by 300 twin pairs (aged 8 years) and their parents. Child report suggested more frequent sleep problems than…

Systematic observations of affiliative interaction in 15 stable peer groups were conducted across three years in an urban day care center. Groups contained 193 French-speaking children ranging in age from one to six years. (Author/RH)

Maintains that the "getting into shape" hypothesis of explaining the inverted-U distribution of exercise play across age is likely incorrect. Argues that the biological study of human physical activity play, as recommended by Pellegrini and Smith (1998), will reveal whether physical activity play represents an example of…