Scientists Explain The Mystery Behind Why 50% Of People Have No Inner Monologue

Some of us operate as though a first-person narrator lives in our heads to document our thoughts, inner turmoils, and experiences. While often speaking without the literary prowess of a Shakespearean soliloquy, inner monologues can be a way for many people to process the world and their existence within it. Moreover, many of us employ various methods, such that researchers have observed that spontaneous inner speech is only present roughly 25% of the time. Determining the exact percentage of people who entirely lack an inner monologue has proved elusive, but researchers have hypotheses as to how this develops. Recent studies have suggested that inner speech is a function of dorsal language stream development and that alterations in this process could contribute to a lack of inner monologue.

In the brain, there are two different language tracks: the dorsal and ventral streams. Each contains specific structures and matures at different stages of development, with the dorsal stream developing later. The ventral language stream is useful for word identification and the assigning of meaning, whereas the dorsal language stream helps to articulate acoustic sounds. Although it remains a hypothesis in need of testing and which has yet to be supported with significant biological data, some researchers assert that, as the dorsal language stream matures at a later time in development, those who lack inner monologues completely have differentially developed connections and parts of the brain within the dorsal stream.

There are other ways that people organize their thoughts independent of inner speech. This does not mean that their minds are blank — simply that they do not process things by internally hearing a voice. Many people feature images in their minds and prefer to visualize as opposed to "hear" their thoughts. Some estimates actually suggest that this inner seeing is the most commonly employed method of engaging with our thoughts. Interestingly, certain individuals are unable to conjure images in the mind, and this phenomenon is known as aphantasia. Meanwhile, the complete lack of inner hearing, whether an internal voice or imagining sounds like music, is called anauralia and is correlated with aphantasia.

In general, anauralia is rare, only representing roughly 0.8% of all people. However, approximately 82% of people with aphantasia also have anauralia. It is common to synonymize inner monologue with thought. In "Theaetetus," when asked how he defined thought, Socrates said, "As the talk which the soul has with itself about any subjects which it is considering." He goes on to mention that this talk is had in silence with oneself. Of course, we now know that not everyone thinks in this way. Some individuals with anauralia have described talking aloud to themselves to process things. Others think of things more abstractly, like recalling the structure of a song as opposed to its exact sound. People with anauralia generally have better attention, self-regulation, and mindfulness compared to those who can imagine sounds.