Single word production in nonfluent progressive aphasia.

We present an experiment investigation of the spoken single word production of two patients with nonfluent progressive aphasia. In Experiment 1, a task effect (reading > repetition > naming) suggested that phonological information available from task stimuli facilitated the patients' speech production; a length effect reflected the increased difficulty of phonological processing required for long words compared with that required for shorter words. Experiment 2 compared repetition, reading, copying, and writing to dictation tasks and demonstrated that a correspondence between input and output modality also facilitated performance. Experiment 3 showed that the patients' access to appropriate phonology in reading was positively related to the degree of correlation between orthographic and phonological forms. These results are discussed with reference to an account of pathologically weakened connections between nodes in an interactive spreading activation model of speech production of the type described by Dell (1986).