An Effect of Imageability on the Production of Phonological Errors in Auditory Repetition

Inthis paper, wedescribeindetail theperformanceon avariety of tests of language processing of a patient (PS) who shows a strong effect of imageability in auditory repetition. Unlike deep dysphasic patients (e.g. Franklin, Howard, & Patterson, 1994, 1995; Valdois, Carbonnel, David, Rousset, & Pellat, 1995), who also show effects of imageability, PS does not make semantic errors in auditory repetition. Instead, he makes a preponderance of phonological errors on words of low imageability when repeating words aloud. PS also makes phonological errors on a wide range of tasks that involve spoken word production including picture naming, which suggests that he has suffered damage to the lexical-semantic route at the level of the representations in the phonological output lexicon. Results from tests of nonword repetition suggests that PS has also suffered damage to the nonlexical repetition route. We argue that the critical difference between PS and patients who make semantic errors is that PS’s nonword repetition impairment appears to be somewhat less severe than that found in deep dysphasia. Although they are both impaired, it appears that the lexical and nonlexical routes can work together to improve PS’s repetition performance and prevent semantic errors, consistent with Hillis and Caramazza’s (1991) summation hypothesis. When the semantic route is unavailable, as appears to be the case for many words of low imageability, then PS’s repetition performance depends entirely on the nonlexical route, resulting in a large number of phonological errors.