Instinct is the word used to describe inherent dispositions towards particular actions. Instincts are generally an inherented pattern of responses or reactions to certain kinds of situations. In humans, they are most easily observed in responses to emotions. Instincts generally serve to set in motion mechanisms that evoke an organism to action. The particular actions performed may be influenced by learning, environments, and natural principles. Generally, instinct is not used to describe an existing condition or established state.

Examples can be observed in the behavior of animals, which perform various activities (sometimes complex) that are not based upon prior experience (such as reproduction and feeding by insects). Other examples include animal fighting, animal courtship behavior, and internal escape functions.

Some sociobiologists and ethologists have attempted to comprehend human and animal social behavior in terms of instincts. Psychoanalysts have stated that instinct refers to human motivational forces (such as sex and aggression). This use of the term has mainly been disregarded. The motivational forces among humans are now generally referred to as instinctual drives.

See also: Animal psychology, Ego, Superego and Id, Psychology, Ethology, Sociobiology, Reason, Unconscious mind, Culture theory