THE EFFECT OF REPERTORY GRID SCALE SIZE AND RATING DIRECTION ON STRUCTURAL MEASURES OF DIFFERENTIATION

Previous work by Soldz and Soldz (1989) indicated that variations in repertory grid features can have a significant impact on the interpretation of the Landfield Functionally Independent Construction Score (FIC), which is a measure of cognitive differentiation. In this study, we showed that four different grid measures (FIC, Total number of zeroes, and the number of midpoint ratings used to indicate either equality or nonapplicability) can be effected by the use of a certain scale size (3-point, 7-point, 13-point), and by the direction of administration (completing the grid in a downwards direction vs. an across-wise direction). In addition, correlations between the number of zero ratings and the total FIC scores for each of the different scale sizes and directions showed evidence to support and to qualify previous work conducted by Soldz and Soldz (1989). In general, high positive correlations were found, suggesting the impact of zero ratings on FIC scores. But the magnitude of the correlations between the zero ratings and the total FIC scores varied as a function of the scale size, the direction of administration, and the meaning of the zero rating (neutrality vs. nonapplicability), raising theoretical, as well as procedural, considerations for future repertory grid research.