Neuropolitics: “Openness” and Cortical Thickness

Brain anatomy–gyruses

I ran across an interesting study today, on openness, creativity, and cortical thickness.

The psychological trait of “openness”–that is, willingness to try new things or experiences–correlates with other traits like creativity and political liberalism. (This might be changing as cultural shifts are changing what people mean by “liberalism,” but it was true a decade ago and is still statistically true today.)

Researchers took a set of 185 intelligent people studying or employed in STEM, gave them personality tests intended to measure “openness,” and then scanned their brains to measure cortical thickness in various areas.

According to Citizendium, “Cortical thickness” is:

a brain morphometric measure used to describe the combined thickness of the layers of the cerebral cortex in mammalian brains, either in local terms or as a global average for the entire brain. Given that cortical thickness roughly correlates with the number of neurons within an ontogenetic column, it is often taken as indicative of the cognitive abilities of an individual, albeit the latter are known to have multiple determinants.

According to the article in PsyPost, reporting on the study:

“The key finding from our study was that there was a negative correlation between Openness and cortical thickness in regions of the brain that underlie memory and cognitive control. This is an interesting finding because typically reduced cortical thickness is associated with decreased cognitive function, including lower psychometric measures of intelligence,” Vartanian told PsyPost.”

Citizendium explains some of the issues associated with too thin or thick cortexs:

Typical values in adult humans are between 1.5 and 3 mm, and during aging, a decrease (also known as cortical thinning) on the order of about 10 μm per year can be observed [3]. Deviations from these patterns can be used as diagnostic indicators for brain disorders: While Alzheimer’s disease, even very early on, is characterized by pronounced cortical thinning[4], Williams syndrome patients exhibit an increase in cortical thickness of about 5-10% in some regions [5], and lissencephalic patients show drastic thickening, up to several centimetres in occipital regions[6].

Obviously people with Alzheimer’s have difficulty remembering things, but people with Williams Syndrome also tend to be low-IQ and have difficulty with memory.

Of course, the cortex is a big region, and it may matter specifically where yours is thin or thick. In this study, the thinness was found in the left middle frontal gyrus, left middle temporal gyrus, left superior temporal gyrus, left inferior parietal lobule, right inferior parietal lobule, and right middle temporal gyrus.

These are areas that, according to the study’s authors, have previously been shown to be activated during neuroimaging studies of creativity, and so the specific places you would expect to see some kind of anatomical difference in particularly creative people.

Hypothetically, maybe reduced cortical thickness, in some people, makes them worse at remembering specific kinds of experiences–and thus more likely to try new ones. For example, if I remember very strongly that I like Tomato Sauce A, and that I hate Tomato Sauce B, I’m likely to just keep buying A. But if every time I go to the store I only have a vague memory that there was a tomato sauce I really liked, I might just pick sauces at random–eventually trying all of them.

The authors have a different interpretation:

“We believe that the reason why Openness is associated with reduced cortical thickness is that this condition reduces the person’s ability to filter the contents of thought, thereby facilitating greater immersion in the sensory, cognitive, and emotional information that might otherwise have been filtered out of consciousness.”

So, less meta-brain, more direct experience? Less worrying, more experiencing?

The authors note a few problems with the study (for starters, it is hardly a representative sample of either “creative” people nor exceptional geniuses, being limited to people in STEM,) but it is still an interesting piece of data and I hope to see more like it.


If you want to read more about brains, I recommend Kurzweil’s How to Create a Mind, which I am reading now. It goes into some detail on relevant brain structures, and how they work to create memories, recognize patterns, and let us create thought. (Incidentally, the link goes to Amazon Smile, which raises money for charity; I selected St. Jude’s.)