Using Mixture Models in Temperament Research

Abstract

Temperamental characteristics can be conceptualised as continuous dimensions or qualitative categories. The continuous versus categorical question concerns the underlying temperamental characteristics and not the measured variables, which can be recorded in either continuous or categorical forms. This paper argues for a categorical conceptualisation of temperamental characteristics and applies a finite mixture model appropriate to this view to two sets of longitudinal observations of infants and young children. This statistical approach provides a good description of the observed predictive relation between behavioural profiles of children at 4 months and the degree of behavioural signs of fear at 14 months. An advantage of the mixture model approach to this data, relative to more standard approaches to developmental data, is that because it takes into account an a-priori theory, it can be used to address improvements and refinements to theories and experimental designs in a straightforward manner.