16 baby rhesus monkeys separated from mothers and placed in a cage with two "wire model" mothers
One plain wire, the other covered in cloth
Condition 1 - milk dispensed by plain wire mother
Condition 2 - milk dispensed by cloth mother
Babies spent most time cuddling cloth mother
When frightened, they ran to the cloth mother
Condition 1 would take milk from the plain wire mother, but cuddled the cloth mother when finished
Comfort > food in attachment