Factors Affecting Interpersonal Construct Differentiation When Measured Using the Repertory Grid

This article focuses on the notion of Interpersonal Construct Differentiation (ICD) and its measurement, using measures derived from the repertory grid technique. To study the nature of these measures and factors such as grid size and type of scale that could affect them, a set of randomly generated grid data sets are compared to a sample of grids administered to subjects, among which we can distinguish a clinical (n = 422) and a nonclinical (n = 304) sample. Results show that ICD related measures derived from 140 randomly generated grids are clearly distinct from those of subjects. Subjects' grids show lower levels of ICD, polarization, and conflict. Grid size and type of scale exert a powerful mathematical effect on the values of these measures, as illustrated by the sample of random grids, but the grid size effect seems to vanish when applied to the subject sample. However, this mathematical effect should not be ignored in further research.