Fear is a state induced by perceived danger or
threat that occurs in certain types of
organisms, which causes a change in metabolic and organ functions and ultimately a change in behavior, such as fleeing, hiding or freezing from perceived traumatic events. Fear in human beings may occur in response to a specific
stimulus occurring in the present, or in anticipation or expectation of a future threat perceived as a
risk to body or life. The fear response arises from the
perception of
danger leading to confrontation with or escape from/avoiding the threat (also known as the
fight-or-flight response), which in extreme cases of fear (
horror and terror) can be a freeze response or
paralysis. In humans and animals, fear is modulated by the process of
cognition and learning. Thus fear is judged as
rational or appropriate and
irrational or inappropriate. An irrational fear is called a
phobia.