LeCun posed a Twitter challenge about gears rotating in a circle where you twist one gear and must determine which direction gear 6 or gear 7 rotates; with 8 gears it's easy (everything rotates) but with 7 the system is overconstrained (nothing moves); GPT-4 initially failed this reasoning task until someone added 'by Yann LeCun' to the prompt, after which it solved it correctly, suggesting context about intellectual difficulty triggered more careful reasoning.