NEEDS or DRIVES.In this theory, Hull proposed a person's behaviour is an external display of his desire to satisfy his physical deficiencies.Hull BASED his theory on the earlier theories that correlate to the concepts of motivation.His theory is grounded on the principle of homeostasis, believing that behaviour is ONE of the ways in which a person can maintain the state of homeostasis or balance.The theory was further developed by Kenneth Spence as it began to be a major theory of motivation in the late 1940s.A “drive" is a state of arousal or tension triggered by a person’s physiological or biological needs. These needs include hunger, thirst, NEED for warmth, etc. In this theory, Hull stated that drives give origin to an individual’s motivation.When a person’s drive emerges, he will be in an unpleasant state of tension and the person will behave in such a way that this tension is reduced.