Harlow was interested in comparing the effects of attachment and mother deprivation on the infant-mother bond. Harry Harlow was an American psychologist who, during the 1960s, set out to study Bowlby's theory of attachment and maternal deprivation in his laboratory. For this, he conducted an experiment with Rhesus monkeys.What Harlow did was, basically, to separate some baby monkeys from their mothers and observe how their maternal deprivation was expressed. But he did not just watch passively, but he introduced into this research an element with which it would be easier to know what monkey babies felt. This element was the dilemma of choosing between something similar to physical contact related to affection and warmth, or food.