Created two monkey mothers (one wire, one cloth). 8 rhesus monkeys studied for 165 days, half fed from wire mother, half from cloth. When scared, monkeys ran to cloth mother. In a room full of objects, wire mother offered no comfort but cloth mother did. All monkeys spent 17-18 hours per day with cloth mother. Long term effects inlcuded abnormal mating behaviour, freezing or fleeing when introduced to other monkeys, and harming their young. Suggests there is more to the formation of an attachment than provision of food.