The extent to which people experience “inner speech” varies greatly, and the differences matter for performing certain cognitive tasks

Participants with weak inner voices did worse at psychological tasks that measure, say, verbal memory than did those with strong inner voices. The researchers have even proposed calling a lack of inner speech “anendophasia” and hope that naming it will help facilitate further research. The study adds to growing evidence that our inner mental worlds can be profoundly different. “It speaks to the surprising diversity of our subjective experiences,” Lupyan says.

Psychologists think we use inner speech to assist in various mental functions.