Properties of psychological variables at the mean or variance level can differ between persons and within persons across multiple time points. For example, cross-sectional findings between persons of different ages do not necessarily reflect the development of a single person over time. Recently, there has been an increased interest in the…

Research on effects of home computer use on children's development of cognitive abilities and skills has yielded conflicting results, with some studies showing positive effects, others no effects, and yet others negative effects. These studies have typically used non-experimental designs and one of the main reasons for the conflicting results is…

Best practice in gifted and talented identification procedures involves making decisions on the basis of multiple measures. However, very little research has investigated the impact of different methods of combining multiple measures. This article examines the consequences of the conjunctive ("and"), disjunctive/complementary…

The relationship between intelligence and personality has been of scientific interest for over 100 years. However, most contemporary estimates of these relationships are limited because they do not separate the variance due to general and narrow cognitive abilities. This study demonstrates that this methodological oversight can distort estimates…