Artificial intelligence can ace exams and write essays, but give it a classic psychology test of focus and it quickly falls apart. A new study from PNAS Nexus shows that leading AI models—including GPT-4o, Claude 3.5 Sonnet, and Gemini 2.5—struggle to maintain attention as tasks grow longer, a weakness that has important lessons for human cognition.
The Research
Researchers led by Suketu Patel gave several top large language models (LLMs) the Stroop task, a well-known psychological test. In this test, color words appear in colored ink, and participants must name the ink color rather than read the word. For example, the word "red" printed in blue ink requires suppressing the automatic reading habit. When given short lists of five words, the AI models performed well, with GPT-4o achieving 91% accuracy. But as lists grew, performance collapsed. At ten words, GPT-4o's accuracy fell to 57%; at forty words, it dropped to just 15%. Claude 3.5 Sonnet maintained stable performance through twenty words, then plummeted to 24% accuracy at forty words. The researchers observed similar patterns across GPT-5, Claude Opus 4.1, and Gemini 2.5. When matching and mismatched words appeared together, accuracy for mismatched items dropped to nearly zero. The models increasingly defaulted to reading the words instead of naming the ink color, revealing an inability to sustain the instructed goal.
Why It Matters
This study highlights a crucial difference between human and machine attention. Humans also struggle with the Stroop task—reading is more automatic than color naming—but most people maintain stable performance even with long lists. The AI's dramatic accuracy drop suggests that current LLMs lack robust executive control, the set of mental processes that help us regulate attention and resist distractions. Unlike biological brains, these models have no mechanism for maintaining focus over extended sequences. For anyone interested in cognitive abilities, this underscores the value of human attention flexibility. While AI can process vast information, it cannot match our ability to hold a single goal in mind and filter out competing signals.
What You Can Do
To protect your own attention, practice single-tasking. Regularly engage in activities that require sustained focus, such as reading a book without interruption or completing puzzles like the Stroop test yourself. Doing so strengthens your executive control and keeps your mind sharp.
Source: ScienceDaily Mind & Brain
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