A Test Battery for Inner Speech Functions.

Abstract

Inner speech, or the ability to talk to yourself in your head, is one of the most ubiquitous phenomena of everyday experience. Recent years have seen growing interest in the role and function of inner speech in various typical and cognitively impaired populations. Although people vary in their ability to produce inner speech, there is currently no test battery which can be used to evaluate people's inner speech ability. Here we developed a test battery which can be used to evaluate individual differences in the ability to access the auditory word form internally. We developed and standardized five tests: rhyme judgment of pictures and written words, homophone judgment of written words and non-words, and judgment of lexical stress of written words. The tasks were administered to adult healthy native British English speakers (age range 20-72, n = 28-97, varies between tests). In all tests, some items were excluded based on low success rates among participants, or documented regional variability in accent. Level of education, but not age, correlated with task performance for some of the tasks, and there were no gender difference in performance. A process of standardization resulted in a battery of tests which can be used to assess natural variability of inner speech abilities among English speaking adults.