Fear conditioning is the method by which organisms learn to fear new stimuli. It is a form of learning in which fear is associated with a particular neutral context (e.g., a room) or neutral stimulus (e.g., a tone). This can be done by pairing the neutral stimulus with an aversive stimulus (e.g., a shock, loud noise, or unpleasant odor). Eventually, the neutral stimulus alone can elicit the state of fear. In the vocabulary of classical conditioning, the neutral stimulus or context is the "conditioned stimulus" (CS), the aversive stimulus is the "unconditioned stimulus" (US), and the fear is the "conditioned response" (CR). Learned redirects here. ... Fear is an unpleasant feeling of perceived risk or danger, real or not. ... Classical conditioning, also called Pavlovian conditioning or respondent conditioning, is a type of learning found in animals, caused by the association (or pairing) of two stimuli. ...

In humans, conditioned fear is often measured with verbal report and galvanic skin response. In other animals, conditioned fear is often measured with freezing (a period of watchful immobility) or fear potentiated startle (the augmetation of the startle reflex by a fearful stimulus). Changes in heart rate, breathing, and muscle responses via electromyography can also be used to measure conditioned fear. Galvanic skin response (or GSR), also known as electrodermal response (EDR) or psychogalvanic reflex (PGR), is a method of measuring the electrical resistance of the skin and interpreting it as an image of activity in certain parts of the body. ... A reflex action or reflex is a biological control system linking stimulus to response and mediated by a reflex arc. ... The heart rate is the number of contractions of the heart in one minute. ... For the play Breath by Samuel Beckett, see Breath (play). ... Electromyography (EMG) is a medical technique for measuring muscle response to nervous stimulation. ...

Fear conditioning is thought to depend upon an area of the brain called the amygdala. Ablation or deactivating of the amygdala can prevent both the learning and expression of fear. Some types of fear conditioning (e.g. contextual and trace) also involve the hippocampus. Fear conditioning is used to study the formation of fear memory and to investigate the processes that may lead to pathological conditions such as phobias and post-traumatic stress disorder. Location of the amygdala in the human brain Located in the brains medial temporal lobe, the almond-shaped amygdala (in Latin, corpus amygdaloideum) is believed to play a key role in the emotions. ... Learned redirects here. ... The location of the hippocampus in the human brain. ... Memory is a function of the brain: the ability to retain information. ... The term phobia, which comes from the Greek word for fear (φόβος, fobos), denotes a number of psychological and physiological conditions that can range from serious disabilities to common fears to minor quirks. ... Post-traumatic stress disorder (PTSD) is a term for the psychological consequences of exposure to or confrontation with stressful experiences, which involve actual or threatened death, serious physical injury or a threat to physical integrity and which the person found highly traumatic. ...

See also:

• classical conditioning
• eyeblink conditioning