Why Humans Experience Fear
We can only guess at the reason why human beings experience fear, but the brain has several mechanisms for this complex emotion. In addition to a specialized circuit that processes sensory inputs, fear processing also depends on the valence of the threat. The valence of fear determines its importance and valence in turn controls action. The process consists of three distinct psychological processes: salience, valence-attribution, and fear processing.
While fear is a normal, healthy response to perceived threats, phobias are irrational reactions that occur without any rational basis. Humans experience fear because of its adaptive function for the survival of our species. When a threat occurs, our brain releases chemicals called stress hormones that cause the body to react in a threatening way. As a result, we feel anxiety, stress, and even disgust. In some cases, fear is even a symptom of mental health disorders.
While many people have irrational fears, the exact cause of these phobias is unknown. Many people who suffer from such fears alter their lifestyles in an attempt to avoid triggers. For example, some people may try to avoid subways or regions where rare animals live. But this doesn’t work for everyone. People who are unable to swim may experience a fear of deep water, and learn to swim safely. Nevertheless, fear is healthy when it warns us of danger. In other cases, however, it can be unnecessarily strong when the situation does not call for it.
Although animal studies have helped us to understand the mechanisms behind human fear, they are not the definitive answer to why we experience fear. Animal studies of human fear tend to focus on a single species and fail to account for the differences between humans and nonhuman primates. Moreover, it ignores the role of brain parts in forming ad hoc concepts. It’s only when researchers study fear in humans that they get a clearer picture of what’s happening in the brain.