This review of two distinct areas of research--brain research and psycho-epistemology--indicates a possible link between the two which may potentially help to identify an as yet unknown molar trait which could be responsible for divergent opinions regarding teaching and learning theories, and may help to explain differential achievement when these theories are empirically investigated. A theoretical parallel between research in psycho-epistemology and hemispheric dominance is established, and it is suggested that an instrument known as the Psycho-Epistemic Style Inventory can be used to assess hemispheric dominance. Some empirical evidence is furnished to indicate the existence of a relationship between hemispheric (epistemic) dominance in teachers and learners on the one hand, and their field of specialization and/or preferred subject matter on the other. The theoretical and practical implications are noted, as well as directions for future research. Forty-four references are provided. (Author/MER)