learning through reinforcement (operant)
dollard + miller (1950) claimed infants feel discomfort when hungry and therefore want food to get rid of their discomfort. infants find that if they cry, their mother will come and feed them - therefore discomfort is removed.
this is called negative reinforcement. the infant associates the mother with food and the infant therefore wants to be close to the mother, to keep food close. this produces attachment behaviour (i.e. distress when separated)