RESUMEN
While previous research has demonstrated that words can be processed more rapidly and/or more accurately than random strings of letters, it has not been convincingly demonstrated that the superior processing of words is a visual effect. In the present experiment, the cases of letters were manipulated in letter strings that were to be compared on the basis of physical identity. Mean response time was shorter for words than for nonwords even for pairs of letter strings that differed only in case (e.g., site-site). This finding implies that the advantage of words over nonwords (the familiarity effect) typically observed in the simultaneous matching task is not due solely to comparison of either the word names or the letter names and, thus, that at least part of the familiarity effect must be due to more rapid formation and/or comparison of visual representations of the two letter strings when they are words. Further analysis failed to reveal a significant involvement of phonemic or lexical codes in the comparison judgments.