The Flynn Effect is one of the most ubiquitous and confusing phenomena in modern psychology. Attributed to James Flynn of New Zealand (though actually coined by Richard Herrnstein and Charles Murray of “The Bell Curve” fame), it states that IQ scores have been rising for nearly as long as people have been taking tests. It hardly matters which assessment you take; scores are better now than 50 or 100 years ago. In short, people are getting smarter.
At least, they used to be.
Before addressing some recent developments, it’s worth exploring the single greatest controversy in the field of IQ testing: nature versus nurture. We all know that our intelligence—which IQ tests supposedly measure, though we shouldn’t use the terms interchangeably—depends on both our genes and our environment. Like everything else, our intellectual development is influenced both by our parents and how we are raised, and we compartmentalize these influences into the categories of heredity and environment. Neither exists in isolation, of course, but it’s a handy way of looking at the issue.
Few scientists would ever claim to fall exclusively on one side of the nature/nurture spectrum. Still, sometimes it seems like the bulk of current research is obsessed with heredity. I recently attended a conference held by the International Society for Intelligence Research, and the dominant view there was that 60 to 80 percent of our intellectual variance is due to our parents. We’re not screwed if our mother and father are below average intellectually, but the odds of becoming the next Einstein are certainly against us. Neuroscientists are even examining the effect on a genetic level, and pretty soon I wouldn’t be surprised if a list of “IQ genes” starts being thrown around.
Which brings us back to the Flynn Effect, because most researchers believe that the increases in IQ are due to environmental factors. Improvements in diet, education, and access to information have all created greater opportunities for cognitive development. Until now. As I hinted before, the Flynn Effect has reversed in recent years, and now IQ scores are decreasing. And according to a recent study by Bernt Bratsberg and Ole Rogeberg of the Ragnar Frisch Centre for Economic Research in Norway, again the cause is our environment.
In fact, the drop appears to be between a half and two points per decade, and we’re right in the middle of it.
Though the details of the study are complex, the summary is pretty simple—Bratsberg and Rogeberg looked at IQ changes over time, but with a focus on siblings. By showing that IQ declines happen within families too, meaning that younger brothers and sisters are working at a slight intellectual disadvantage by being born later, they showed that the reverse Flynn Effect doesn’t just describe broad populations. It affects everybody, even siblings.
So, what does this mean? First, the good news—we can’t blame immigration or higher birth rates among less intellectually gifted individuals. This is a common argument among strong-hereditarian advocates (note: I did not call them racists, which is another topic altogether), though a weak one, because it doesn’t explain IQ decreases within families. It also makes some pretty big assumptions about immigration, birth rates, and race that science has yet to support.
Second, maybe it’s time to think of IQ in terms beyond nature versus nurture. Nobody can argue against math, and the math certainly shows that our genetic background strongly influences our cognitive development. Maybe even as much as 60-80 percent, but these numbers are deceptive. They assume that genetics and environment fall into separate compartments.
Take, for example, this rather evil thought experiment—what if two children were locked in a room for their first 12 years with no education. What would be the intellectual differences between these children? Probably none at all, regardless of their genetic history. Compare that with our current world, where access to good schools, the internet, and even basic nutrition varies wildly.
Clearly nature and nurture interact in a deep way, which makes any portioning of IQ variance difficult. It also puts us at risk of overestimating the importance of our genes. Even scientists aren't immune—when 75 intelligence researchers were asked what they thought was the primary cause of this reverse-Flynn Effect, the winner by far was the belief that low-intelligence individuals have more children. The second was migration.
So, what can we do to keep our IQ scores high? The first step is easy—eat healthy, take education seriously, and get enough sleep. It’s not sexy advice, but it works. Voting to support our educational systems, and not just for the academically gifted, would also be a good start.
Lastly, take comfort that even scientists get things wrong sometimes. Genes are important, to be sure, but they're not helping us much now. Blogs summarizing entire research disciplines into just a few sentences probably aren't great either, but that's life.
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Bratsberg, B. and Rogeberg, O. (2018). Flynn effect and its reversal are both environmentally caused. Proceedings of the National Academy of Sciences, 115, 1-5.
Rindermann, H., Becker, D., and Coyle, T. (2016). Survey of expert opinion on intelligence: The Flynn effect and the future of intelligence. Personality and Individual Differences, 106, 242-247.