Different theories have attempted to define and explain the construct of motivation
from diverse points of view. Some approximations share various principles, but others
differ partly or wholly in their postulates. However, they all coincide in their striving to
explain the motivations of human beings when they think and behave in particular ways.
These different theories can be grouped into three main categories. In first place,
we should mention Freud’s psychoanalytic theory and Hull’s drive theory, both of which
consider that stress reduction exerts a considerable influence on behaviour.