School performance is one of the most stable and heritable psychological characteristics. Notwithstanding, monozygotic twins (MZ), who have identical genotypes, differ in school performance. These MZ differences result from non-shared environments that do not contribute to the similarity within twin pairs. Because to date few non-shared…

The structure of temperament proposed by the New York Longitudinal Study (NYLS) was compared to Buss and Plomin's EASI temperament theory. A similar sociability factor emerged from both systems, but other temperaments were unique. The two systems were merged to form the Colorado Childhood Temperament Inventory. (Author/MV)

Genetic and environmental influences on heart rate were studied in samples of twin pairs in middle childhood. Heart rate was measured in resting situation and under two task conditions. Heart rate was related to parental ratings of shyness, emotionality, and selective attention measure. Multivariate analysis suggested that covariance between heart…

Considered two unexplored issues concerning use of parental ratings to measure young children's temperament: (1) the validity of such measures, and (2) parents' projection of their own personality in rating their children. (Author/DB)

Investigated genetic change and continuity within the domains of temperament, emotion, and cognition and language for 200 pairs of twins assessed at 14 and 20 months of age. Correlations of measures at the two ages indicated that individual differences in the second year of life showed greater change than continuity on most measures. (MDM)

Conducted a trivariate genetic analysis of the Home Observation for Measurement of the Environment (HOME), Mental Development Index (MDI), and Task Orientation (TO). Found that for 101 nonadoptive and 92 adoptive sibling pairs at 12 and 24 months of age, TO explained the remaining genetic variance on the HOME not explained by the MDI. (MDM)

Despite a substantial body of research suggesting genetic influence on educationally relevant behavioural traits, it is not clear how the nature-nurture question is perceived by teachers. In order to answer this question, we surveyed 667 UK primary school teachers, and for comparison also surveyed 1,340 parents about their perceptions of genetic…

Discusses the concept of temperament interactions in the context of statistical interaction. Categorizes temperament interactions that involve temperament as an independent variable, as a dependent variable, or as both. Describes use of hierarchical multiple regression for the analysis of temperament interactions. (Author/CI)

Experimental research suggests the differentiation of "nice" and "nasty" theory of mind (ToM). Over 5000 parents from the Twins Early Development Study reported on nice (e.g., being considerate) and nasty (e.g., blaming others) behaviours following their twins' second, third, and fourth birthdays. Factor analyses yielded four factors and it was…