Measuring Inner Speech Objectively and Subjectively in Aphasia

Background: Many people with aphasia and people without brain injury talk to themselves in their heads, i.e., have “inner speech.” Inner speech may be more preserved compared with spoken speech for some people with aphasia and may serve a variety of functions (e.g., emotion regulation), which motivates us to provide a high-fidelity characterization of it. Researchers have used multiple methods to measure this internal phenomenon in the past, which we combine here for the first time in a single study. Aims: We compare performance between individuals with and without aphasia on inner speech tasks that assess inner speech “inthe- moment” to general subjective impressions of inner speech to tease apart the relationship of aphasia severity to inner speech. Methods and Procedures: Twenty people with mild-moderate aphasia and twenty neurotypical controls completed several inner speech tasks, including objective silent rhyme judgements (picture, written, and auditory), subjective reports of inner speech during naming, and subjective rating scales about inner speech experience more generally. Outcomes and Results: In-the-moment inner speech during silent rhyming tasks was associated with aphasia severity only for picture and written rhyming but not auditory rhyming. In-the-moment inner speech reports during silent naming were not associated with aphasia severity, nor were the subjective ratings about general inner speech experience. Individuals with and without aphasia demonstrated a variety of subjective general inner speech experiences, demonstrating heterogeneity of this phenomenon more broadly. Conclusions: Methods of measuring inner speech complement each other and speak to different facets of the inner speech phenomenon, and clinicians and researchers must carefully choose the method(s) that will provide the information about inner speech that they desire.