Describes a mixed longitudinal analysis of 1,356 twins, (three to 15-years-old) their siblings, and cousins, who underwent a battery of physical and behavioral tests. The covariance structure analysis method in biometrical genetics was employed to specify determinants of the structure of cognitive abilities, to indicate how these change during…

Examines language effects in class-inclusion performance with 224 children ages 3 through 12 by comparing the standard Piagetian question with two alternate question forms. Overall, the findings were inconsistent with the Piagetian assertion that logical inability produces errors in comparing subclasses; inclusion performance was a function of…

A group of 91 fifth and sixth graders kept diaries of liked and disliked peer behaviors and important peer activities for a week. Another group of 81 fifth and sixth graders rated the importance and prevalence of each activity and indicated most liked and disliked positive and negative behaviors. Three main functions were evident. (RH)

Maintains that conflict in close relationships characterizes both the United States and Japan, with differences only in the style and timing of its manifestations. Asserts that the potentially fruitful strategy of Rothbaum et al. is constrained by their cross-cultural comparative methodology. (Author/KB)

Asked Dutch university and Russian high school students to sort statements in terms of moral sophistication to investigate hierarchical stage structure of moral stages. Found that sorting statements representative of stages below one's own was straightforward; sorting statements above one's stage was difficult, suggesting that reflective…