While an internal monologue is a common occurrence, not everyone experiences it. There's a lot that researchers have yet to uncover about why some people frequently “hear” an inner voice, and what it means. Read on to learn what's been discovered about this psychological phenomenon thus far.

How rare is inner speech?

The average frequency of inner speaking across those who took part in the research, at 23%, masks a huge range: from 100% – i.e. for some people, every time they were sampled they had some kind of internal monologue or inner conversation going on – to 0% – i.e. some people were never speaking to themselves internally.

What percentage of the population doesn't have an inner voice?

In a study performed with 30 college students, an average of 26% of participants reported having some sort of internal speech — some up to 75% while others had none at all.