Discrepancy between inner and overt speech: Implications for post-stroke aphasia and normal language processing

Background: Patients with aphasia often complain that there is a poor correlation between the words they think (inner speech) and the words they say (overt speech). Aims: This study tried to characterise the relation between inner speech and overt speech in post-stroke aphasia. Methods & Procedures: We tested language abilities, speech apraxia, and performance on inner speech tasks, including homophone and rhyme judgements, of 27 patients with chronic post-stroke aphasia. Outcomes & Results: The patients with aphasia were distributed across the entire spectrum of abilities related to both inner and overt speech. For most patients, performance levels of inner and overt speech were similar. However, some patients had relatively better-preserved inner speech with a marked deficit in overt speech, while in others the opposite pattern was observed. Conclusions: The results are discussed within the framework of current models of language, and their implications for language therapy and aphasia diagnosis are outlined.