Perception gap
The difference between the productivity effect developers report and the one that is measured; consistently positive for AI tools.
Surveys report large self-assessed gains — 99% of developers say they save time (Atlassian), >80% say AI made them more productive (DORA) — while controlled measurements find small, zero or negative effects on experienced developers on real work. In METR's trial the gap was 39 percentage points. Reasons include time saved on typing being spent on prompting and reviewing, and AI making work feel easier without making it faster.