Is Gen Z IQ Dropping?

Is "brain rot" real? Discover the science behind the Gen Z IQ drop, the Flynn effect reversal, and digital learning. Read the guide and try the RIOT test!

Dr. Russell T. WarneChief Scientist

"Brain rot" — a term that Oxford University Press named its 2024 Word of the Year after a 230% surge in usage between 2023 and 2024, captures a genuine anxiety about what is happening to the cognitive development of younger generations. The concern isn't new, but the data behind it has become considerably harder to dismiss. Multiple lines of evidence, across multiple countries, now suggest that the long-standing upward trend in IQ scores has not merely stalled among younger cohorts; it has reversed in measurable ways for the generation that grew up with smartphones, social media, and short-form content as default cognitive environments.

Whether that reversal constitutes a genuine decline in intelligence or something more nuanced is a question that deserves a careful answer rather than a headline.

The Flynn Effect and What It Means That It's Reversing

To understand what's happening with Gen Z cognitive scores, you need to start with the Flynn Effect: the documented rise of roughly three IQ points per decade observed in most developed nations throughout the 20th century. The gains were attributed to better nutrition, expanded access to formal education, smaller family sizes, and what researcher James Flynn himself described as populations increasingly putting on "scientific spectacles" — thinking in more abstract, categorical, and analytical ways because modern life demanded it.

The reversal of that trend, now documented across multiple countries, is one of the more significant cognitive science findings of the past decade. Norwegian military-conscript IQ scores peaked for the 1975 birth cohort and have declined approximately 0.2 points per year since. Compulsory military IQ tests from Finland, Norway, Denmark, Estonia, Britain, France, the Netherlands, and Australia all show declines beginning in the mid-1990s. In the United Kingdom, longitudinal analyses from the British Cohort Study reveal a cumulative decline of up to five IQ points in verbal skills and structured reasoning among post-1970 cohorts.

The critical methodological finding that makes this data particularly compelling comes from Bratsberg and Rogeberg's landmark 2018 PNAS study. Analyzing cognitive test scores from over 730,000 Norwegian male military conscripts born 1962–1991, they found that the decline appeared within families — brothers born later scored lower than brothers born earlier — directly ruling out genetic causes and immigration as primary drivers. Their conclusion: the Flynn Effect and its reversal are both environmentally caused. Whatever is driving the decline, it is something in the environment, not in the gene pool — which, as they noted, also means it is potentially reversible.

What the Gen Z-Specific Evidence Shows

The reversal documented in military conscript data maps directly onto the generation now labeled Gen Z — broadly defined as those born between 1997 and 2012, who are the first cohort to have grown up with smartphones as a normal part of childhood and adolescence.

Earlier this year, neuroscientist Jared Cooney Horvath provided written testimony to the U.S. Senate Committee on Commerce, Science, and Transportation stating that Gen Z is the first generation in modern history to score lower on standardized cognitive tests than the previous one — 2 to 4 points lower than Millennials on average across a range of measures. He cited data showing that cognitive abilities started to decline around 2010, correlating with the widespread adoption of smartphones and the shift toward technology-centered classroom learning. In 2024, the U.S. spent more than $30 billion putting laptops and tablets in schools. The outcome, according to Horvath and a growing body of learning science, was the opposite of what was intended.

The pattern is not confined to the United States. Researchers highlight declines particularly in reading comprehension, sustained attention, mathematical reasoning, and memory performance — precisely the cognitive functions most dependent on sustained, effortful cognitive engagement rather than rapid scanning and retrieval.

Which Cognitive Domains Are Most Affected

One of the most important nuances in the current data is that the decline is not uniform across cognitive domains — and that pattern tells us something meaningful about its causes.

The declines appear most pronounced in mathematical problem-solving and abstract reasoning — precisely the areas where formal education drills students most intensively and where sustained cognitive engagement is most required. Meanwhile, measures of practical intelligence, social intelligence, and creative problem-solving in real-world contexts have not shown equivalent declines.

A 2024 cohort study at the University of Vienna, tracking IQ test results from 2005 to 2024, found something even more nuanced. While scores have continued to rise in some cases — especially among individuals with initially lower scores — the overall coherence between different cognitive abilities has weakened. In technical terms, the study observed a decline in the positive manifold — the pattern where people who perform well in one cognitive domain tend to perform well across others, which reflects the strength of the underlying general intelligence factor. The population may be becoming more cognitively specialized or differentiated, with domain-specific skills remaining intact while the general factor underlying cross-domain performance weakens.

This is a more subtle and more concerning finding than a simple score decline, because it suggests a structural change in how cognitive abilities are organized rather than a uniform reduction in all of them.

Why Is This Happening?

The environmental causes of the reversal are the subject of active research and genuine scientific debate. No single factor has been established as the primary driver, but several converging hypotheses have accumulating evidence behind them.

Screen-based learning replacing deep reading. Horvath's Senate testimony and subsequent media coverage focused heavily on the replacement of textbooks with tablets and the corresponding shift from deep, linear reading — which builds sustained comprehension, abstract reasoning, and working memory — to scanning, swiping, and consuming fragmented information. Complex knowledge acquisition typically requires prolonged focus, structured reading, and active discussion. When information arrives primarily as summaries, algorithm-selected clips, or instant answers from AI tools, the sustained analytical processing that builds cognitive capacity simply doesn't happen with the same frequency or depth.

Social media and attention fragmentation. A Baylor University study published in November 2025 found that TikTok required the least cognitive effort of any platform tested — even less than Instagram Reels and YouTube Shorts — by balancing relevant content with unexpected interruptions that prevent the development of sustained attentional focus. The term "brain rot" entered the Oxford dictionary precisely because younger users themselves recognized this dynamic in their own experience. Concerns over social media addiction have become serious enough that 1,600 plaintiffs across 350 families and 250 school districts have filed lawsuits alleging that Meta, Snap, TikTok, and YouTube created addictive platforms leading to measurable mental health and developmental challenges in children.

Declining educational quality and cognitive demand. Horvath argued before the Senate that technology has not upgraded the quality of education — it has reduced the cognitive demands placed on students. "Humans are biologically programmed to learn from other humans and from deep study," he told senators, "not flipping through screens for bullet point summaries."

The Part That Requires Caution

While the evidence for a reversal of the Flynn Effect is now substantial and the Gen Z framing has real data behind it, I want to flag the parts of this story that require more careful interpretation than the headlines typically provide.

First, the 2–4 point decline figure cited in media coverage reflects population averages across broad cohorts — it is not a statement about any individual Gen Z person's cognitive ability. Individual variation within generations vastly exceeds variation between generations. There are Gen Z individuals with exceptional cognitive profiles, and the generational average tells you nothing about any specific person.

Second, the decline is domain-specific rather than universal. The cognitive skills most affected — sustained attention, deep reading comprehension, linear mathematical reasoning — are precisely the skills that the modern information environment has least incentive to develop. Practical, adaptive, and social intelligence measures have not shown equivalent declines. This may mean that what is being measured reflects an environmental mismatch between what IQ tests reward and what contemporary daily life trains, rather than a straightforward reduction in cognitive capacity.

Third, as the within-family data conclusively shows, this is environmental — which means it is reversible. A generation that has grown up with their cognitive development shaped by fragmented, low-effort digital environments could, under different educational conditions, develop the sustained reasoning capacities that current test data suggests are declining. This is not a biological destiny for an entire generation.

The Takeaway

The evidence that Gen Z cognitive scores are declining compared to previous generations is real, multi-national, and now well-supported enough to be discussed seriously rather than dismissed as generational anxiety. The reversal of the Flynn Effect is documented across military conscript data from eight countries, within-family designs that rule out genetic explanations, and longitudinal survey instruments. The domains most affected — sustained attention, abstract reasoning, reading comprehension — are precisely the ones most dependent on the kind of deep, effortful cognitive engagement that the modern digital environment consistently replaces with lower-effort alternatives.

What the data does not support is fatalism about any individual's cognitive potential, or the conclusion that an entire generation is permanently cognitively impaired. The same environmental logic that explains the decline also explains why the decline is, in principle, reversible — and why understanding your own cognitive profile, rather than assuming it conforms to a generational average, is more informative than any population-level statistic.

If you want to understand where your own cognitive profile actually sits — across fluid reasoning, working memory, processing speed, and the other domains where the current data shows the largest declines — the RIOT gives you a domain-level answer that no generational headline can provide.