What Exactly Is IQ? |

Each of us possesses a diversity of skills, cognitive and otherwise. However, the cluster of skills we consider to be constituents of intelligence differ in different societies and at different times. IQ tests measure what we value in Western, educated, industrialized, rich, and democratic (WEIRD) societies – right now – and so it should be no surprise that IQ test scores predict school and work performance in WEIRD societies, particularly for skills considered to require higher cognition. But just as our ability to get work done on a computer depends not just on high-powered hardware – the latest Thinkpad or Macbook – but also on the right software – Excel or Photoshop – it is also impossible to think about intelligence without considering both hardware (genes) and software (culture). What is the evidence for this?

In the mid-twentieth century, Norway increased the number of years of compulsory schooling from seven to nine years. Children born days apart received a difference of two years in education due to this change in policy. Norway also has mandatory military service where all conscripts are given an IQ test. And so, we can go beyond correlation and determine how much this extra education affected IQ test performance in a causal manner.

Those two extra years of education gave those who received it an average of over seven IQ points – around half a standard deviation – a massive bump in brilliance. Not all natural experiments are as free from other potential influences as this one, but a meta-analysis of 142 tests from forty-two similar quasi-experiments like this with over 600,000 participants, conducted by Stuart Ritchie and Elliot Tucker-Drob, came to the same conclusion – the overall effect of education on IQ test performance is between one and five IQ points per year of education. The authors concluded, ‘Education appears to be the most consistent, robust, and durable method yet to be identified for raising intelligence.’

Earlier interventions and larger effects
Norway’s policy change only affected adolescent education, so it was probably underestimating the overall effect of education on IQ. Earlier interventions tend to have larger effects – older dogs are harder to teach new tricks.

My colleagues and I spent two years searching the globe to see if there was a site where schools were yet to arrive but were also arriving in a sufficiently randomized natural experimental way. In 2016 we finally found one in southern Africa, on the Kunene river border between Namibia and Angola.

The Himba are a cow-herding semi-nomadic pastoralist people who live on both sides of the Kunene and continue to practice their traditional way of life, crossing the river to meet and marry, but largely living on one side or the other due to the difficulty in taking their cattle across. As a result of this meeting and marrying, both sides of the river are part of the same genetic and cultural population, but schools have been introduced to the Namibian Himba but not yet to their cousins in Angola.

IQ test performance correlates with age in WEIRD societies. We assume children get smarter as they get older. But here’s the problem – thanks to truancy laws, age correlates almost perfectly with the number of years of school in our society. Age is an almost perfect proxy for education. Are kids getting higher raw IQ test scores because they’re getting older or because they’re receiving more education?

To find out, we compared the Himba who went to school with those who did not on the supposedly culture-free Raven’s Colored Progressive Matrices. As you might imagine, children with education had higher scores than children without education, and the more education they received, the higher their scores. But here’s what was surprising: among the children without access to education, older children had roughly the same scores as younger children on the Raven’s test—8-year-olds performed the same as 18-year-olds. Their scores weren’t improving with age the way they do among the schooled Himba and as they do in our schooled societies.

Older children with or without education are still developing, maturing, and becoming more skilled just as they are anywhere. And the Angolan Himba survive and thrive and succeed as people do anywhere. However, the Angolan Himba skills would not be reflected in our society’s traditional IQ test performance. Think about it, these supposedly culture-free tests still rely on colors and shapes that we take time to teach our children. IQ tests measure what schools in our society are delivering.

Puzzling questions
In our study, we’re also replicating data collected by Russian psychologist Alexander Luria who looked at a similar education revolution happening in Uzbekistan in the 1920s. Luria tested simple logical propositions such as ‘If p then q’, famously explaining once that ‘In the far north, where there is snow, all bears are white.’ As part of his test, he asked participants the following:

‘Novaya Zemlya is in the far north, and there is always snow there. What color are the bears there?’

This was a simple question readily answered by even young children in our society and individuals with access to education in Uzbekistan. But this simple question was met with puzzlement from those not exposed to formal education. Here is a typical response:

‘I don’t know. I’ve seen a black bear; I’ve never seen any others.’

Luria also asked questions that resemble the Sesame Street song ‘One Of These Things’. For example, he asked which of the following are alike: a hammer, a saw, a log, and a hatchet. Here is a transcript of a conversation with Rakmat, a thirty-year-old with no education, that reveals the relational way of thinking:

‘They’re all alike,’ he said. ‘I think all of them have to be here. See, if you’re going to saw, you need a saw, and if you have to split something, you need a hatchet. So they’re all needed here.’

We tried to explain the task by saying, ‘Look, here you have three adults and one child. Now clearly the child doesn’t belong in this group.’

Rakmat replied, ‘Oh, but the boy must stay with the others! All three of them are working, you see, and if they have to keep running out to fetch things, they’ll never get the job done, but the boy can do the running for them . . . The boy will learn; that’ll be better, then they’ll all be able to work well together.’

‘Look,’ we said, ‘here you have three wheels and a pair of pliers. Surely, the pliers and the wheels aren’t alike in any way, are they?’

‘No, they all fit together. I know the pliers don’t look like the wheels, but you’ll need them if you have to tighten something in the wheels.’

‘But you can use one word for the wheels that you can’t for the pliers – isn’t that so?’

‘Yes, I know that, but you’ve got to have the pliers. You can lift iron with them and it’s heavy, you know.’

With all this in mind, what is an IQ test? An IQ test is really a measure of cultural imprinting. We are taught how things in our world are related to each other and it shapes how we think about the world. These cognitive tools change our brains in profound ways that are invisible to us without the ability to travel back in time or to the few far-flung places in which schools have yet to arrive. Remember, all intelligence tests and the entirety of experimental psychology were developed after schools had already become widespread.