Abstract
Many personality theorists postulate a hierarchical structure in trait words. However, most evidences are indirect, mainly because the theorists rely on factor-analytic methods. Assuming a global structure, the factor approach is not necessarily adequate to investigate concrete relationship among trait words. In this study, we used two direct measures to study the hierarchical structure: direct comparison of breadth and asymmetry class-inclusion judgment on trait concepts. Results of three experiments in general confirmed robustness of the hierarchical structure in the domain of personality traits. Traits were organized in the structure at several different levels of abstractness. But the structure was fuzzy in nature, unlike the taxonomy in biology. It was also found that inter-relations among traits could vary considerably from individual to individual. Cognitive complexity may be one of the variables that explain such an individual difference.
