Fear, as generally described, is an emotional response to a perceived threat from the environment. From an evolutionary perspective, fear is understood as a mechanism that keeps an organism safe from a threat to its existence. As such, fear and the reactions that fear triggers are both innate and learned. In other words, an organism is born with the ability to react to a threatening situation and learns though experiences to fear certain stimuli.

This entry provides an overview of what fear is and how it is functionally understood, followed by a discussion of how fear affects individuals posttrauma, specifically in regard to theoretical conceptualizations and the relationship of fear and posttraumatic stress disorder (PTSD). This entry focuses on understanding the posttraumatic fear reaction from a ...