Fear, Posttraumatic

Overview

In general, fear is considered a basic and crucial reaction in complex organisms. The fear response evolved as an adaptive behavior to keep organisms safe from a predatory threat. Organisms that were the quickest to react to the threat ultimately survived and preserved their right to reproduce. Depending on the species, a variety of different behaviors are triggered by the fear response. In humans, among other species, the fear response can trigger the fight, flight, or freeze response. Each of these responses has its own significance and adaptive quality.

Fear is also considered a basic, learned emotion. How an individual learns to fear a stimulus can be understood in terms of Ivan Pavlov's classical conditioning. As such, a previously neutral conditioned stimulus—for example, a bell—is paired with an aversive unconditioned stimulus, such as a shock. After pairing the two together several times, the conditioned stimulus is enough to elicit a conditioned response—for example, of fear—on its own. With intense experiences such as trauma, this can occur after one pairing.

The fear response includes a physiological reaction that occurs via the sympathetic and autonomic nervous systems. In humans, this reaction includes arousal symptoms such as increased heart rate, tightening of muscles for quick movement, dilation of pupils to allow for clearer vision, increased sweating, and heightening of senses to fully perceive the situation. This physiological response prepares the individual to behave in an appropriate fashion, which most likely leads to avoiding the threat by the “flight” response. However, an individual may also freeze when encountering a threatening stimulus.

Fear differs from anxiety insofar as anxiety is typically a response to a situation that is uncontrollable, less intense, and does not involve the immediate necessity for escape or avoidance behavior. In addition, fear is typically a present-oriented reaction, and anxiety is future-oriented.

When a traumatic event occurs, an individual will react with intense fear. Fear responses in humans, particularly the flight response, consist of avoidance, hypervigilance, and a startle response and can help preserve physical integrity in a life-threatening situation. According to learning theory, the avoidance of stimuli associated with trauma will prevent [Page 265]exposure to similar events. Hypervigilance and exaggerated startle responses also increase the possibility of detecting dangerous situations. Individuals who experience a traumatic event often suffer from a dysregulated fear response, specifically in relation to fear inhibition. In other words, they are unable to distinguish between safe and dangerous environmental cues. Furthermore, the fear response will often be associated with situations that are not dangerous and do not pose a risk. As such, the inability to inhibit the fear response in the presence of a safe environment can affect the functioning of the individual in interpersonal and social contexts. Fear can also lead to a variety of other emotions in humans, including anxiety, horror, panic, and terror—all of which can depend on the individual experience of the fear-evoking situation. These other emotions often add to the complexity and compound the response, especially with the inability to inhibit the fear response.

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