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The Reverse Flynn Effect

By Alanna Hendren

IQ or Intelligence Quotient scores are important for people with intellectual or developmental disabilities because they determine teaching strategies, special education assistant hours and whether or not adults qualify for CLBC supports since their mandate is people with IQ scores of 70 or less, but they have a long history.

Although humans had tried to measure intelligence earlier, the first IQ test considered valid was developed by French psychologist Alfred Binet in 1904. The French government had just passed a law making education mandatory for all children and wanted to find a way to identify children who may need extra help to learn. Binet’s test met the immediate needs of educators, but he warned that the test measured attention, memory, and problem-solving skills but did not measure other aspects of intelligence like creativity, emotional intelligence, or changes in IQ over time. The test yielded the ‘mental age’ of the individual by matching scores against the average age of people who had the same score.

Binet’s test was standardized and better quantified in 1916 at Stanford University in California by psychologist Lewis Terman. Terman took the ‘mental age’ scores from the Binet Test, divided by the chronological age of the test-taker, then multiplied by 100. If a child’s mental age is 5 and their chronological age is 5, then 5/5 x 100 = 100, so their IQ is 100. If a child’s mental age is 11 and chronological age is 10, then their IQ is 11/10 x 100 = 110.

The Stanford-Binet test has been complemented by other more probing tests over time, but all are standardized so 100 is the most common score. Two-thirds of the population scores between 85 and 115, the ‘normal range’ of intelligence. The other third falls above or below the normal range in equal proportion.

In 1984, New Zealand educator, James R. Flynn researched how much average IQ test scores had increased over the 20th century and found they increased by an average of 3 points per decade. Flynn attributed this increase to better nutrition. Flynn continued his work and other scientists followed suit until they all noticed that children born in 1975 reached ‘peak IQ’ and average intelligence had been dropping ever since. This is called the ‘Reverse Flynn Effect’.

No one knows for sure why IQs are dropping but a study by Norwegian scientists with access to 30 years of IQ test results for young adults determined that the drop was not due to genetics. The IQ scores of younger siblings dropped more than their older brothers and sisters, in spite of the same parentage and the trend was evident across age groups. This ruled out immigration, which was the most common theory about the cause of the Reverse Flynn Effect.

Genetics have a profound impact on our cognitive skills but humans are their genetics interacting with their environments and our environments have been getting progressively worse since 1975. Junk food showed up in a big way around 1975, along with massive amounts of chemicals in fertilizers and elsewhere, lead in decaying water pipes, radiation from nuclear-reactor accidents, and preservatives, dyes, and hormones in food. These chemicals are also thought to be responsible for the ballooning incidence of autism that started in the 1980s and continues today. The impact of the chemicals that surround us on developing fetuses and infant brains has never been tested.

Then there are all the post-modern problems caused by screens and cell phones – decreasing attention spans, multitasking, fake news, and so on, but a biological explanation makes the most sense. Some researchers have noted that IQ scores are dropping in the same populations where sperm counts are also decreasing, probably because of chemicals that leech from plastics or disrupt endocrine systems, poor diets, obesity and too much time spent sitting down. The world needs more research in this area.

Some of these causes are under our self-control but many are not. Our governments must take a more active role in regulating plastics use and make sure that chemicals are used safely in other industries. Municipalities need to ensure that common infrastructure is not leaching lead or other chemicals into the water people drink. Educators should teach all children about how eating could be hazardous to their health. This does not absolve families of their responsibilities to keep themselves healthy, but the Flynn Effect will likely continue to reverse until everyone agrees that action should be taken.