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The Science of Fear

What makes up the "fear system"?

The parts of the brain that are responsible for creating your physical reaction to fear are referred to as the “fear system.” It includes the amygdala, the brain stem, the hippocampus, the hypothalamus, the prefrontal cortex, and the thalamus. 

How does your brain interpret a scary event?

While experiencing a fearful situation, your brain first has to decide what is the appropriate reaction. The hippocampus is responsible for interpreting the event and comparing it to past experiences in order to determine how you should react by establishing context. By processing the stimuli around you, the hippocampus tells the amygdala whether or not this is this a situation that requires a fight-or-flight response or if it is simply a false alarm. 

What is responsible for the fight-or-flight response?

“Fight-or-flight” is your body’s instinctive physiological response to a threatening situation. It prepares it to either put up a fight against the threat or flee by freezing the muscles, increasing the heart rate and blood pressure, and pumping stress hormones into the blood stream to prepare your body to run. Though many parts of the fear system play a part in triggering this response, the hypothalamus is responsible for turning on the fight-or-flight response, which involves the sympathetic nervous system and the adrenal-cortical system. 

What signals your adrenal glands to start pumping?

Adrenaline is a hormone that is responsible for most of your physical reaction to fear. When facing a stressful or fearful situation, your hypothalamus signals the adrenal gland to start pumping, which leads to an increase in blood circulation, breathing, and metabolism—all of which is to prepare your muscles for exertion. 

What makes you "frozen" with fear?

Fear also affects different species in similar ways; in fact, we can learn a lot from animals about how we respond when we are frightened. When an animal such as a deer is in fear, its body freezes. This is helpful in the animal kingdom, since most potential predators will not be able to see prey that isn’t moving. Thanks to evolution, humans have a similar response, and the feeling of being “frozen in fear” is triggered by the brain stem. Because of a sudden flood of adrenaline and other stress hormones, your muscles automatically tense up. This reaction is also responsible for causing the hair on the surface of your skin to stand on end. 

Are there different types of fear?

Watching the stock market drop and killing a spider require different responses. While both elicit fear, one requires a physical reaction, while the other will just make your stomach turn. The thalamus receives input from the senses and decides to send information to either the sensory cortex for conscious fear or the amygdala for fear used as a defense mechanism. Conscious fear would be more appropriate for witnessing an event that you don’t have any control over, while defensive fear physically and mentally prepares you for action against the threat at hand.

Is fear contagious?

While a certain degree of fear is instinctual, we learn how to exhibit it through experiences with fear-inducing events and from the people around us, such as our family and friends. Phobias often originate as a learned behavior by children from their parents. Simply witnessing fear in others also has the power to elicit fear in ourselves. According to a recent study, emotions such as fear and disgust can be conveyed via the smell of hormones found in sweat. The results of this study found that when people unknowingly smelled the sweat produced by someone who was in fear, they in turn produced facial expressions that are consistent with being scared.  

Is fear addicting?

Though we come into this world knowing how to be afraid because our brains have evolved to deal with nature, the threats we respond to could be wildly different. Some people are terrified to watch scary movies, while others are afraid of heights. Since fear and adrenaline are so closely linked, some people enjoy the “adrenaline high” that comes from being scared, while others avoid feeling fear as much as possible. Researchers are learning that the reason some people are drawn to intense, fear-inducing thrills while others avoid them at all costs could be due to personality traits that are formed at the most fundamental level. High-sensation seekers tend to be more stimulated by any sort of arousing stimuli, and they might even be at a higher risk for other behaviors such as drug and alcohol abuse. 

Is fear harmful?

Just like oil and water or toothpaste and orange juice, fear and learning simply do not mix. While in a state of fear, the stress hormones that are released into our bloodstream have a negative effect on learning and memory. Low and medium levels of the stress hormone cortisol are actually able to improve learning and enhance our memory, but high levels induced by fear have the opposite effect. 

Is fear useful?

Without fear, we probably wouldn’t live for very long, because we would be carelessly jumping off of roofs, walking into oncoming traffic, and staring into the face of deadly animals. The way our body responds to fear is a meant to bring an evolutionary advantage, since fear promotes survival. Additionally, our response to fear makes our body more equipped to handle the situation at hand. Adrenaline dilates our pupils, allowing us to take in more information; it tenses our muscles in case we need to run; and it increases our heart rate and breathing, readying us for action. However, in reality, the way fear affects our body could potentially be either helpful or harmful in stressful situations. It depends on how well we are able to focus when overcome with fear. Some people are able to thrive when filled with stress and adrenaline, while others simply shut down with anxiety.