The Colour Theory of Intelligence

I don’t want to write anymore, I want to move to political videos or something, but I have another theory.

For a while now I have been trying to come up with a persuasive argument for why verbal tests should not be used in clinical IQ assessments. Some points were:

• Older people (45-65) score just as well, and often even better, than young people (16-25) on verbal tests. All other tests have younger people doing better, which makes sense because younger brains are healthier and sharper.

• Another point is that people with a “verbal-tilt” have a much greater opportunity to practice their interest than people with a “spatial-tilt”. We use words everyday. Someone who is socially oriented will read more, write more, talk more, listen more etc over the course of many years. But with spatial tests, or logic tests or whatever, the material that is used has never really been seen before. It is totally different from language.

I think these are good points, but my main argument was an intuitive based feeling that verbal ability is not a “true” category of intelligence. Now I have an interesting analogy for that.

Verbal ability, I thought, relies on memory (to remember the word) and reasoning (to decide which word to use). On the other hand, reasoning and memory do not rely on verbal ability at all.

In this sense they are like colours. Yellow, blue and red are the 3 primary colours. They cannot be made by a mixture of any other colours. They exist on their own. Green, orange and purple are secondary colours, they can be made using the primary colours.

Reasoning, memory and spatial ability are the 3 primary types of intelligence. All other types of intelligence can be derived from some combination of them.

The 3 primary types do not rely on any other type, conceptually. It is true that a logical test will inevitably incorporate some other aspects, and the same goes for memory tests and spatial tests, but that could be because we haven’t devised the perfect test items. Conceptually they are almost totally distinct. But verbal ability tests, by their nature, need to incorporate memory and reasoning. Verbal ability is conceptually derived from the other two.

So what are the other secondary types? I decided on maths and music.

This makes sense to me. Verbal ability is a combination of reasoning and memory, and is directly opposite to spatial ability (often thought to be the antithesis of verbal ability, or that the two have some kind of zero-sum relationship that revolves around other, more central types of intelligence).

Why use school subjects as secondary types of intelligence? Well, music can be understood as auditory processing, and maths can be understood as quantitative knowledge, both of which are elements in the Cattell-Horn-Carroll (CHC) theory of intelligence.

The CHC is widely accepted as the most comprehensive and empirically supported theory of cognitive abilities. I applied it to the intelligence wheel.

• Gc - crystallised intelligence

• Grw - reading and writing

• Gf - fluid reasoning

• Gs - processing speed

• Gq - quantitative knowledge

• Gk - kinesthetic ability

• Gv - visual processing

• Gt- reaction time

• Ga - auditory processing

• Gsm - short term memory

• Glr - long term storage and retrieval

• Gkn - domain specific knowledge

Its a bit of a stretch, and I used some categories that have been added by McGrew to the CHC theory, but you get the picture. And if we did want to use school subjects for the wheel model, it fits alright. Here are the 12 most common university subjects (arguably) and then the 6 most common school subjects. In Australia we use the term English like Americans use Literature.

History is mostly just memorising. Spatial ability predicts musical success, sporting success and mathematical success, so that makes sense. But what is most interesting to me is the physical map that this model creates.

There was a study in 2008, about genetics. They took DNA from all different kinds of Europeans. Then they did a PCA analysis, where they map out the genetic distances between people. The resulting map looked almost identical to a map of Europe.

And this makes total sense, because Italy is further from Scotland than Norway is, and so should be genetically further as well. And Spain is physically further from Poland then Austria is, etc etc. And when you triangulate everything you either end up with a map of Europe, or a reverse map of Europe.

Genes mirror geography within Europe

Here we characterize genetic variation in a sample of 3,000 European individuals genotyped at over half a million variable DNA sites in the human genome. Despite low average levels of genetic differentiation among Europeans, we find a close correspondence between genetic and geographic distances; indeed, a geographical map of Europe arises naturally as an efficient two-dimensional summary of genetic variation in Europeans.

Anyway, my point is that this colour wheel model of intelligence can be superimposed onto a birds eye view of the brain, and I think it lines up pretty well. Its hard to say because I can’t get a birds eye view of a brain with all the labels of parts and what they do, but it seems pretty good.

So the front of the brain is understood to be used for logical reasoning basically. The back of the brain is used more for visual processing.

It is also understood that “the left side of the cerebrum is associated with speech and processing language, while the right is associated with nonverbal memory and spatial awareness”, according to Google.

It is also understood that for short term memory, the left side stores more verbal information and the right side more spatial or visual memories. In general, memory seems to be stored in the middle parts of the brain (both top and bottom) in the cerebral cortex and the hippocampus. But also, the cerebellum, which is right at the back underneath the occipital lobe, is responsible for coordinating movement and storing physical memory.

Broca’s area is a region in the frontal lobe of the dominant hemisphere, usually the left, of the brain with functions linked to speech production.

Wernicke’s area is is one of the two parts of the cerebral cortex that are linked to speech, the other being Broca's area. It is involved in the comprehension of written and spoken language, in contrast to Broca's area, which is primarily involved in the production of language. It is traditionally thought to reside in Brodmann area 22, which is located in the superior temporal gyrus in the dominant cerebral hemisphere, which is the left hemisphere in about 95% of right-handed individuals and 70% of left-handed individuals.

Music: “Professional musicians use the occipital cortex, which is the visual cortex, when they listen to music, while laypersons, like me, use the temporal lobe — the auditory and language center. This suggests that [musicians] might visualize a music score when they are listening to music,” Sugaya says.¹

Cant find anything conclusive on mathematical ability, but if the left side is used primarily for language, I imagine the right is used primarily for maths.

1. https://www.ucf.edu/pegasus/your-brain-on-music/#:~:text=%E2%80%9CProfessional%20musicians%20use%20the%20occipital,to%20music%2C%E2%80%9D%20Sugaya%20says.