Where do aphasic phonological errors come from? Evidence from phoneme movement errors in picture naming

Abstract

This paper analyses the incidence and distribution of phonemic misordering errors (or "contextual" errors) in the phonologically related nonword responses of aphasic individuals. A diverse group of 22 individuals was examined in two separate picture naming studies. Contextual error rates were found to be above chance for only two of the participants. These participants had one unique feature: both were more accurate at word endings than word beginnings. Both also had a diagnosis of conduction aphasia and produced errors that were phonologically close to their targets, and at least one showed strong word length effects; however, none of these features was unique to them. The "contextual" individuals were not distinguishable from the other participants on the basis of: their production of formal paraphasias; their relative performance on word naming and repetition; or their performance on words relative to nonwords. The findings from this study are inconsistent with the notion that contextual errors result from a malfunction involving a dedicated postlexical phoneme sequencing stage. An alternative, single-stage account of phonological encoding is offered, in which differences in contextual errors rates are attributed to individual variation in word production strategies.