Testing single‐ and dual‐route computational models of auditory repetition with new data from six aphasic patients

Background: Both single-route and dual-route models of spoken word production have been proposed to account for auditory repetition performance in aphasic patients. Aims: We examined the extent to which Foygel and Dell's (2000) single-route model and Hanley, Dell, Kay, and Baron's (2004) dual-route model could successfully predict the repetition performance of six aphasic patients who made errors in picture naming and auditory repetition. Methods & Procedures: The six aphasic patients were tested on a variety of linguistic tasks. The models used performance on naming and nonword repetition tasks to predict real-word repetition scores. Outcome & Results: All six patients performed reasonably well at nonword repetition, but showed no evidence of using a non-lexical route when repeating real words. The repetition performance of all six patients was therefore better simulated by the single-route model than the dual-route model. Conclusion: Although the dual-route model successfully predicted the real-word repetition performance of the two patients reported by Hanley et al. (2004), it overestimated the performance of the six patients reported here. If the dual-route model is correct, then only a minority of patients appear to benefit from using the non-lexical route when repeating real words.