For over a century IQS around the world had been rising. But now the trend appears to be reversing. What can be done to stave off the decline?
IQ scores were on the rise ever since the first intelligence test was invented more than a century ago. But in recent years the trend appears to be slowing down or even reversing. Have we passed the peak of intellectual development? Professor Jakob Pietschnig explains why IQ scores seem to be falling—and how the decline can be mitigated.
Professor Pietschnig, you study and compare the results of intelligence tests around the world. Just how high is your own IQ?
My tested IQ is absurdly high. But that has more to do with my familiarity with the structure of IQ tests and the answers than it does with any actual ability. That’s why in my native Austria people are required to have a degree in psychology in order to obtain and administer IQ tests. If the contents were accessible to anyone, the world would suddenly seem a lot smarter than it is.
Does that mean IQ tests don’t necessarily reveal the actual intelligence of the person who is being tested?
You might say that one’s IQ is a measurement of intelligence, and intelligence is what is measured by an IQ test. This reflects the fact that science has failed over the past 100 years or so to clearly define what intelligence really is. Which of the many abilities we generally consider to reflect “intelligence” should we include in the definition? The ability to think logically, of course. But what about concentration, perception, or memory? Or the spatial imagination? Perhaps even the fine motor skills? In practice, there are countless tests to measure dozens of these attributes. And each test has a slightly different emphasis, depending on the ability that’s being assessed. A test for air traffic controllers will focus more on concentration and sense of time and space, for example, than on language.
So IQ isn’t always the same?
That’s correct. No two IQ tests measure exactly the same thing. But—and this is important—all IQ tests measure the ability to solve problems,
and the results of two different IQ tests will point in the same direction. Someone who is good at math, for example, will typically also be good at logical thinking. And since there is only one right answer to each of the questions on an IQ test, the results are objective. That is an important difference from tests that are meant to measure emotional intelligence. When a person is asked, for example, to say what mood is being suggested by a photograph, there is room for interpretation. Intelligence can be far more accurately assessed than other personality traits.
Doesn’t an IQ test stigmatize people who don’t do well?
Does someone who is less intelligent have to try much harder than a smarter person? There is some controversy on the subject. But research has clearly shown that more intelligent people generally take better care of themselves, are better at assessing risk, and deal better with a crisis. They also tend to be happier, more successful, and more affluent. You’ll rarely find a top manager whose IQ is under 110, putting this professional group in the most intelligent 25% of society. At times that seems unfair. You might ask: “Shouldn’t everyone be able to attain their goals if they try hard enough?” Many people—some of them scientists—refuse to accept the causal role intelligence plays in achieving success and instead seek other explanations—motivation level, for example. However no matter how motivated you may be, if you lack the intelligence you need to earn a PHD in physics, you won’t make it, despite how hard you try.
Why is an IQ of 100 considered to be normal?
The assumption is: Intelligence is equally distributed around the world. That’s how we arrive at the famous bell curve. A high percentage of people will solve a similar number of problems with similar success, and a smaller number of outliers will do far better or far worse. Intelligence tests are constructed in such a way— and adjusted if necessary—so most respondents rank in the middle with a score of close to 100. The average deviation from this mean is 15 points in each direction. Scores of less than 70 (in those with learning disabilities) and higher than 130 (in the extremely gifted) represent only around 5% of the total population.
Can practice and training influence the outcome of an IQ test?
We differentiate between fluid and crystallized intelligence. Fluid intelligence entails reasoning, comprehension, and problem solving and is not dependent upon previous knowledge. Crystallized intelligence is a matter of recalling one’s stored knowledge and past experience. Fluid intelligence tends to peak during the mid-twenties and then slowly starts to decrease after that, though some aspects may peak later. As an adult, there is not much a person can do to influence it. Crystallized intelligence relies on one’s factual knowledge. It is experienced-based and increases rapidly up until the age of 20 and then will continue to grow at a somewhat slower speed after that. It is subject to human influence.
What determines how intelligent someone is?
That’s a good question and an excellent topic for discussion. Most people—which includes many of my students—would like the answer to be found in one’s environment: the education, encouragement, etc. They would prefer a world in which we all start out on a level playing field with the same chances of success in life. But our genes also play a role. If you measure the difference in intelligence among the members of two different
families—one with ample resources and the other with limited resources— genetics won’t play as much of a role. Around two-thirds of the difference can be chalked up to environmental factors. However if you compare two equally affluent families, their genes will explain most of the difference in the members’ intelligence. Scientists sharply disagree about how great the genetic influence really is. Estimates range from 10% to as high as 90%.
Do some nationalities tend to be more or less intelligent than others?
There have indeed been IQ studies that compare results internationally. Generally speaking, Asian nations tend to score at the top, followed by Europe and North America, followed by the rest of the world. Back in the 1930s, scientists hypothesized that Western societies would become less intelligent over time because families in the lower classes were having more children and new immigrants tended to be less educated. But in practice such differences usually disappear within a single generation. There have been no lasting negative effects from birth or immigration rates. Instead the data reveal a different relationship.
What is that?
Rather than decreasing—as researchers had predicted— intelligence proved to be on the rise throughout the world, on average by 3 points per decade. A study that was published in 1984 showed that mean intelligence had risen by 3.0 IQ points per decade in America after 1932. The cumulative rise was enormous, amounting to an increase of 15 IQ points in just half a century. Another study published in 1986 concluded that these increases were probably largely due to environmental factors, such as improvements in health and nutrition, greater stimulation from TV, books, educational games, and toys, increased leisure, and a reduction in size of families. Researchers found that while genetic factors could not be ruled out, the gains were too large for genetics to have played a major role. Then data from Scandinavia began to suggest a decline in IQ beginning in the mid-1990s. Tests conducted by the military of 18- and 19-year-olds in Finland, Denmark, Norway, and Sweden showed losses averaging 0.23 points per year in all four countries. And while the annual losses were small, they resulted over the course of a generation in between 6.5 and 7.5 points. that certainly gives one pause for thought.
Does this mean that we may be smarter than our ancestors but we are about to become dumber than our parents?
We do know that the current generation performs better on IQ tests than earlier generations. For one thing, we’re better at guessing, but that does not really explain it.
Intelligence seems to rise and fall in waves. It rose markedly in the 1950s, for instance, during the big economic recovery after World War II. The ready availability of good food, medicines, and education left their mark on fluid intelligence, which rose rapidly. But perhaps there are always limits to growth, whether we’re talking about human intelligence or height, which also increased during the postwar years for some of the same reasons.
So why does the effect seem to be slowing down or reversing?
I suspect it has something to do with increasing specialization. Intelligence is composed of dozens of different aspects, many of which had been actively promoted during the postwar years. Today even young schoolchildren tend to specialize in one sport or activity to the exclusion of others, and specialization continues in college and in the professions. In adult life today, specialist knowledge is a marketable commodity. The era when polymaths were prized for their mastery of multiple subjects and their ability to draw on complex knowledge to solve problems is over. Increasing digitalization has made all of human knowledge available with a few clicks and doesn’t much require the ability to concentrate or to draw on prior knowledge or experience.
So what are your recommendations for children?
I recommend children listen to Mozart, although—contrary to some opinions—doing so does not actually boost the cognitive abilities. However, children do need to have their imagination stimulated. Read to them. Take them outside the home for activities such as museum visits, or play sports or music with them. Make the activities as varied as you can. Don’t be passive: Spend active time with them. As in so many things, parents serve as role models when it comes to intelligence.