Divergent Validity and the Measurement of Processing Capacity

Abstract

I do not disagree with most of the substantive conclusions that Steven Pulos draws, based on his reanalyses of Case and Globerson (1974) and Morra’ s (1994) data. My problem is with his epistemological presuppositions. He writes as if the classic epistemology of exploratory factor analysis is somewhat truer and more rigorous than the epistemology of developmental constructivism. In classical exploratory factor analysis a main semantic assumption is that the obtained factors are indexing causal determinants that can explain the matrix of correlations. However, if we look at what these factors actually are in terms of the operations involved in their extraction, factors appear instead as higher-order descriptive response variables: They represent components of covariation patterns among tests, in terms of subjects’ own responses— relational “ empirical invariants” or latent variables. Thus, even more clearly than correlations themselves, e rst-order factors represent quantie ed relations of equivalence among tests, in terms of the subjects’ responses. One might concede that factors must then stand for relations of coexistence in the tests loading on them— relations among semantic/qualitative facets or aspects that coexist in tests loading on the same factor; these are facets that the tests share. But nothing in the technique of factor analysis tells us which these facets actually are. To answer these questions, factor analysts have traditionally used phenomenology, often a home-grown variety, perhaps a nai ve one. Factor analysts have not until recently (e.g. Frederiksen, Mislevy, & Bejar, 1993) been interested in subjective/rational task analysis— a form of applied phenomenology which, in combination with suitable developmental-process and individual-difference elements, lends itself to the semantic clarie cation of empirical tests. The hierarchical structure of factors proposed by classical factor analysts is predicated on the method of factor extraction, and implies