Introduction. One of the most fruitful fields of research in the psychology of reading has been that concerned with the analysis of specific psychological functions involved in the reading process. A cursory perusal of the literature reveals the fact, however, that the great majority of such investigations have dealt with the mechanical phases of the process, such as typographical factors, eye-movements, rate of reading, and related functions, leaving more or less untouched such mental processes as reasoning, conception, and understanding. The present investigation was undertaken in the hope of shedding some light on at least one of these untouched areas, i.e., the role played by the concept in reading ability.