03
AI can make people feel more productive, even when they're taking longer.
What they believed
20% faster
What was measured
19% slower
In a randomised trial, 16 experienced open-source developers completed 246 real tasks with and without early-2025 AI tools. A 2026 follow-up with newer tools was inconclusive, so this is a warning about measuring impressions, not a verdict on AI.
SourceMETR randomised trial (2025)




