Understanding quantified categorical expressions

A model of categorical inference (Revlis, 1975b) claims that a conversion operation participates in the encoding of quantified, categorical expressions. As a consequence, a reasoner is said to interpret such sentences as “All A are B” in a way that permits it to also be the case that “All B are A.” The present study examines this conception of encoding using a sentence-picture verification task. In two experiments, students were asked to judge whether one of five possible Euler diagrams was true or false of a categorical expression (e.g., All A are B, No A are B, Some A are B, Some A are not B). Verification errors support a three-stage verification model whose major component is access to a “meaning stack” representing the progressive analysis of categorical relations; at the top of that stack is a converted reading of the input sentence. These findings have implications for current conceptions of categorical inference and semantic retrieval.