The Flynn Effect: Are We Getting Smarter? (And Why It Might Be Stopping)

If you could travel back in time to 1910 and administer a modern IQ test to the average person, they would score roughly 70. By today’s standards, that is on the border of intellectual disability.

Conversely, if a “genius” from 1910 traveled to 2026, they might find themselves struggling to keep up with the abstract complexity of a modern workplace.

This phenomenon—the massive, sustained increase in fluid and crystallized intelligence scores throughout the 20th century—is known as the Flynn Effect. Named after political scientist James Flynn, it is one of the most robust findings in the history of psychology.

But there is a twist in the data. After decades of growth, the line has started to curve downward. In strict scientific terms: We might have peaked.

Part 1: The Golden Age of Growth (1930–1995)

For nearly a century, humanity seemed to be on an unstoppable cognitive trajectory. The gains were consistent: roughly 3 IQ points per decade.

What Changed?

It wasn’t genetics. Evolution doesn’t work that fast. The hardware remained the same, but the environment (the “operating system”) was radically upgraded.

1. The Cognitive Demand of Society: In 1900, most jobs were manual. You didn’t need to solve abstract logic puzzles to farm. Today, even navigating a smartphone interface requires a level of abstract reasoning that would baffle a Victorian. Our world has become a 24/7 training camp for Fluid Intelligence ($G_f$).

2. Scientific Spectacles: Flynn argued that we moved from “utilitarian” thinking to “scientific” thinking.

   • Question: “What do dogs and rabbits have in common?”
   • 1900 Answer: “You use dogs to hunt rabbits.” (Concrete, functional).
   • 2026 Answer: “They are both mammals.” (Abstract, taxonomic). This shift in how we think—categorizing the world rather than just living in it—is exactly what IQ tests measure.

3. Nutrition and Health: The elimination of lead paint, the reduction of infectious diseases (which consume energy the brain needs), and the fortification of foods with iodine and iron removed massive biological brakes on brain development.

Part 2: The Anti-Flynn Effect (1995–Present)

Around the turn of the millennium, something disturbing appeared in the data sets of developed nations.

• Norway: IQ scores of military conscripts peaked in the mid-90s and have been sliding since.
• Denmark, Finland, UK: Similar plateaus or declines.
• France: A loss of nearly 4 points between 1999 and 2009.

Scientists call this the Anti-Flynn Effect. The engine of cognitive growth hasn’t just stalled; it has gone into reverse.

The Suspects

1. The “Digital Dementia” Hypothesis

Did the smartphone make us stupid? While technology grants us instant access to Crystallized Intelligence (facts), it may be eroding our working memory and attention span. If you never have to navigate by map, calculate a tip, or remember a phone number, the neural circuits for those tasks atrophy.

• The Danger: We are offloading our cognition to the cloud. We are becoming better at finding information, but worse at processing it deeply.

2. Environmental Toxins

Researchers are increasingly looking at endocrine disruptors. Microplastics, phthalates, and other ubiquitous modern chemicals are known to interfere with thyroid hormones, which are critical for brain development in utero.

3. Dysgenic Fertility

A controversial but statistically significant theory suggested by researchers like Edward Dutton. It posits that in modern societies, there is a negative correlation between intelligence and fertility. Highly educated (high IQ) individuals tend to have fewer children and have them later in life, while those with lower cognitive scores tend to have effectively larger families. Over several generations, this could theoretically lower the genotypic IQ of a population.

Part 3: What Does This Mean for You?

The Flynn Effect teaches us that intelligence is not fixed. It is sensitive—exquisitely so—to environment. If society is currently in a “cognitive recession,” you must build a personal firewall against it.

1. Reclaim Your Attention: Deep reading (books, not tweets) is the only way to train the linear, analytical focus that IQ tests measure.
2. Protect Your Hardware: Minimize exposure to processed foods and environmental toxins.
3. Do The Hard Thing: Don’t let the GPS or the AI do everything. Struggle with the map. Do the math in your head.

The Uneven Geography of the Flynn Effect

It is important to note that the Flynn Effect and its reversal are not uniform across the globe. The picture is more complex:

• Developing nations in sub-Saharan Africa and parts of South Asia continue to show positive Flynn gains, as improvements in nutrition, disease reduction, and access to formal education replicate the conditions that drove 20th-century Western growth.
• East Asian nations like South Korea, Japan, and China showed massive Flynn gains through the latter half of the 20th century, propelled by aggressive educational investment.
• Nordic and Western European nations were the first to show the Anti-Flynn reversal, perhaps because they were the first to reach environmental saturation—the point at which further improvements in nutrition and healthcare yield diminishing cognitive returns.

This suggests that the Flynn Effect is less a story about intelligence itself and more a story about environmental ceilings. Once a population’s environment is “good enough,” the passive cognitive gains stop. What happens next depends on choices—individual and societal.

Conclusion

The 20th century was a free ride. We got smarter just by living in a richer, more complex world. The 21st century is different. The passive gains are gone—at least in the developed world. If you want to maintain—or increase—your intelligence now, you have to fight for it.

The Flynn Effect is no longer a guarantee. It’s a choice. And the most important environmental variable left to optimize is the one you control directly: how you spend your attention.