Measuring inner speech objectively and subjectively in aphasia

BackgroundMany people with aphasia and people without brain injury talk to themselves in their heads, i.e., have “inner speech.” Inner speech may be better than speech out loud for some people with aphasia and may a 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. AimsWe compare performance on inner speech tasks that assess inner speech “in-the-moment” to general subjective impressions of inner speech abilities in individuals with and without aphasia and tease apart the relationship of aphasia severity to inner speech. Methods & ProceduresTwenty 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 & ResultsInner speech during silent rhyming tasks was associated with aphasia severity only for more complex tasks (e.g., picture and written rhyming but not auditory rhyming). In-the-moment inner speech reports during silent naming were not associated with aphasia severity, and 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. ConclusionsMethods of measuring inner speech complement each other and get at 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.