Reading aloud: when the effect of stimulus quality distinguishes between cascaded and thresholded components.

A central feature of many formal accounts of reading aloud, and of Coltheart and colleagues dual-route cascaded model in particular, is that activation across various modules is cascaded. Evidence is reviewed that this assumption is problematic in a particular context, along with a solution that involves thresholding the output of the letter level to the nonlexical routine. Consideration of the known effects of repetition leads to the prediction of a three-way interaction between stimulus quality, repetition, and lexicality in which repetition and stimulus quality interact when reading aloud exception words, but produce additive effects when reading aloud nonwords. The result of such an experiment confirms this prediction, and appears consistent with the localized dual-route model. Implications for other accounts are briefly noted.