When you think all to yourself (not engaging with others) do you hear an inner voice, do you conjure images, or do you just have abstract feelings? For most people the answer is, yes. Recently a Twitter post has triggered people to consider their inner voice, and whether or not they have one. The post was intriguing to many people mostly because they had not considered that other people may be different in this respect than they are. It was not a variable they thought could differ among people.

The episode brings up a few interesting points, the first of which is the core question – how do people think? If you have never considered the question, consider it now. Do you actually “hear” a virtual voice in your head? Do you think mostly in pictures, or in the abstract? Or is the mode of your thought very context dependent – depending on what you are thinking about or what task you are trying to complete.

For me, I think I do everything. If anything I may be biased toward verbal inner monologue, but that may be an artifact of the fact that I write every day and give lots of lectures. I definitely practice lectures and conversations entirely in my head. People who know me well even “catch” me doing this, because I may talk with my hands or throw in the occasional gesture or facial expression while doing so. But I can also be very visual when the task calls for it, bringing to mind detailed images, schematics, or spatial relationships. When I think about abstract concepts, I tend to give them some verbal or visual representation. So I would say, rough estimate, I am 60-40 verbal-visual, but again that may be because of my writing and lecturing.

I have known for a long time that other people (at least those close to me) do not do this nearly as much as I do, and I have also learned over the years of my neurological study and science communication that, generally speaking, there is far more neurodiversity than we naively assume. There are those who essentially have no verbal inner monologue. They are far to the visual end of the spectrum.

At the other end of the spectrum there is “aphantasia” – which is a complete lack of the ability to bring an image to mind. People with this “condition” (if it can be called that) do not appear to suffer any consequence. They can be just as creative as others, and simply use alternate cognitive styles to achieve their tasks.

Despite all the drama online – this neurological/psychological feature of humans is boringly typical. It occurs along a spectrum (not a dichotomy where you are either one or the other), and most people are lumped toward the middle where they use a combination of several cognitive styles. Further, cognitive preferences are a result of genetics, environment, development, and current context all influencing each other. So – pretty much like every other human trait.

Researchers are still trying to work out the nuances and details, which is challenging because it is difficult to objectively record someone’s inner experience. The research so far shows that most people are, as I said, capable of visual, verbal, and abstract inner thought. There is some debate about the number of people capable of hearing an inner voice, but the consensus seems to be “most.” There is one outlier researcher, Russel Hurlburt (the outliers always seem to get disproportionate press) who thinks the number is much lower, perhaps only 26%, and that all other research in the field is flawed. He thinks that asking someone verbally about their inner voice triggers a verbal experience. He may have a point, but I don’t see how this creates an inner voice in those who would not otherwise have one. Perhaps this factors affects how often we experience our inner voice, but not whether or not we have one.

One study with fMRI suggests that visual thought may be dominant over verbal in most people, which they attribute to be evolutionarily older.

I also consider it a very useful take-away from this episode that many people underestimate neurodiversity, and do tend to assume that other people think like they do. This is a known psychological phenomenon. It is good to be reminded that people are different, pretty much in every possible way it’s possible to be different, including some ways you are not even aware of. Further, for much of this diversity, there is no better or worse – just different. There may be different trade-offs, and different strengths and weaknesses, but not necessarily any objective superiority. However, there may be advantages in certain contexts. If you are a writer, having a verbal cognitive style may be an advantage. If you are a visual artist, having a visual cognitive style may help. People probably naturally sort themselves according to their strengths automatically.

This is all in line with evolutionary theory as well. There is a great deal of diversity, which is more or less adaptive to various situations. Populations, however, may also benefit from the diversity itself, especially in a social species with task sharing.

Finally, all this reminds me of how disappointing most science fiction is (as much as I love it). Aliens are usually depressingly human, not just in morphology but also in culture and thought. There are exceptions, but I would love to see more science fiction explore how aliens can be different in how they think. This is really hard, to get out of our own heads and biases, but that is exactly what science fiction is for.

Note – I invite you to describe your own inner experience in the comments, to get an unscientific sample of this variation.