The data supports this claim. Research by Gloria Mark, a professor of informatics at the University of California, Irvine, indicates that our attention span is about a third shorter than in 2004, with the largest drops occurring around 2012. Long-term surveys reveal that the proportion of American adults who have difficulties with basic reading or math has increased notably in the last decade, while the percentage of 18-year-olds reporting difficulties thinking and concentrating soared in the same period. A Financial Times article about these findings raised a surprising but relevant question: "Have humans exceeded their maximum brain capacity?".

Many of these deteriorations in cognitive skills became noticeable from the mid-2010s, just when smartphones became widespread and the digital attention economy experienced explosive growth. A growing body of research suggests that this temporal coincidence is not accidental. A meta-analysis published last fall showed that consumption of short-form video content, such as that offered by apps like TikTok and Instagram, is associated with lower cognitive performance and reduced attention span. Furthermore, the results of an ingenious 2023 experiment revealed that the mere presence of participants' smartphones in a room significantly reduced their ability to concentrate.

The rise of AI has generated new cognitive concerns. A January study, based on surveys and interviews with more than 600 participants, revealed a significant negative correlation between frequent use of AI tools and critical thinking ability. Another recent study, which analyzed brain activity of research subjects writing with the help of large language models, found that brain connectivity systematically decreased with the amount of external support.

The loss of our ability to think is a matter of great importance. Nearly 40% of the United States' gross domestic product comes from so-called knowledge- and technology-intensive industries, from aerospace manufacturing to software development and financial and information services. Companies in these sectors transform advanced human thought into revenue; by weakening our brain capacity, we also threaten to weaken our economy. Notably, productivity growth in the private business sector stagnated during the 2010s, when technology became considerably more distracting.