Not Everybody Has an Inner Voice: Behavioral Consequences of Anendophasia

It is commonly assumed that inner speech—the experience of thought as occurring in a natural language—is a human universal. Recent evidence, however, suggests that the experience of inner speech in adults varies from near constant to nonexistent. We propose a name for a lack of the experience of inner speech—anendophasia—and report four studies examining some of its behavioral consequences. We found that adults who reported low levels of inner speech (N = 46) had lower performance on a verbal working memory task and more difficulty performing rhyme judgments compared with adults who reported high levels of inner speech (N = 47). Task-switching performance—previously linked to endogenous verbal cueing—and categorical effects on perceptual judgments were unrelated to differences in inner speech.