Smart people are less likely to reproduce

Flynn effect: why intelligence does not increase any further

If you're having a bad day, the following mind game might comfort you: 100 years ago you would have been a genius - at least according to the numbers. Even with a mean IQ of 100, you would have had a good chance of an IQ of 130 back then, which corresponds to giftedness. Only around two percent of the total population crack this mark. Bad news for the masterminds of that time: Even the exceptional historical talents would be just good mediocrity according to today's test standards.

This is due to a phenomenon known as the Flynn effect: Since the beginning of the measurements, people have been doing better and better in the IQ tests. For a long time this increase was relatively stable in many industrialized nations at around 0.3 points per year. That may not sound like much, but within ten years the difference already adds up to 3, after a century even to 30 points, which corresponds to the difference between an average and a gifted person. However, it is precisely this effect that has stagnated for a number of years. More recent data sets show that the growth is gradually slowing down in some places. In some countries researchers have even found a decrease in intelligence scores; one already speaks of an »anti-Flynn effect«.

  1. Since the beginning of the intelligence measurement, the IQ has increased steadily on average around the world. But this so-called Flynn effect stagnates in many places or is even reversed.

  2. In Germany, verbal intelligence continues to rise, whereas spatial imagination is going downhill. In Norway, as well as in some other countries, the overall IQ appears to be falling.

  3. A popular explanation: Less intelligent parents would have more children. But at least for Norway this cause could be ruled out. Rather, changes in intelligence can possibly be explained by how well the ability to abstract is trained.

This article is contained in Spectrum Compact, The Measurement of Intelligence

That, in turn, calls alarmists on the scene: "Are we getting dumber?" Asks the German psychiatrist and neuroscientist Manfred Spitzer in 2018 in the specialist journal "Nervenheilkunde" and also has a culprit on hand: It is the increasing media and Internet consumption put our IQ into a gradual decline. But does the stunt in growth measured in some places actually suggest that our intelligence as such is declining - even that humanity is becoming more and more stupid? And why are these irregularities appearing right now?

What does an intelligence test measure?

As early as the early 20th century, the French psychologist Alfred Binet was working on a test that was supposed to measure a general ability of children to solve various tasks. To do this, his test subjects completed a battery of very different tasks. It started with simple questions that almost everyone could answer ("Where's the window?"), And then grew into tough puzzles that only particularly bright children could solve. The Binet-Simon test named after him served as a blueprint for numerous further developments, all of which had a similar objective: the sum of different test questions was intended to capture intelligence as a single, general factor. With this claim, the tests became a powerful tool and the subject of controversial debate. Critics complain that the tests reflect the profile of a western, academic upper class and systematically disadvantage other classes or cultures. In addition, intelligence is often mistaken for an essential human characteristic - psychological tests are actually supposed to serve as a tool for very specific questions. IQ tests have become an indispensable part of modern diagnostics. With their help, experts record learning difficulties, assess the culpability of a defendant in court or search for the most suitable applicant for an open position.

As early as the 1930s, intelligence researchers noticed that their normal values ​​(the average values ​​for comparing, among other things, those of their peers) gradually became incorrect over the years. The mean IQ continued to rise and the calibration had to be readjusted. Anyone who thinks this is nitpicking must bear in mind the far-reaching consequences the result of an intelligence test can have. The eponym of the phenomenon, the New Zealand political scientist James R. Flynn, gives a particularly extreme example: Anyone who is on trial in the USA for murder, for example, may not be executed in some states if they are mentally disabled. If an expert uses an outdated IQ standard for diagnosis, it can happen that he does not recognize a disability as such - in the worst case, the Flynn effect could lead to an unlawful execution.

By the way, researchers are still divided on the exact causes of the Flynn effect, as well as on the reasons for its gradual stagnation. The fact is: Newer data sets are increasingly questioning the Flynn effect in its previous form. Interestingly, the findings differ depending on the country, in some cases even enormously: In the USA, for example, there is no noticeable decrease in IQ; on the contrary, the Flynn effect there apparently continues unchecked. But after decades of rising, the mean IQ has apparently been falling again in several countries - especially northern European countries - since 1995.

Spatial imagination has been going downhill in this country since 1995. In general IQ and vocabulary tests, however, German-speaking test subjects performed increasingly better

Most impressive are the results from Norway. Up until 1991, the lion's share of all young men had to take part in an extensive examination including an IQ test. This created a veritable treasure trove of data for intelligence researchers, which the Norwegian scientists Bernt Bratsberg and Ole Rogeberg analyzed in the 2018 Proceedings of the National Academy of Sciences. They looked at 30 consecutive years since 1962, including more than 700,000 individuals. Their finding: While the IQ values ​​rose continuously until the mid-1970s, they then gradually decreased again by almost two points per decade. There are also increasing results from other countries that indicate an apparent reversal of the Flynn effect: from Finland and Estonia, for example, but also from Kuwait and the Sudanese capital Khartoum.