Fear

• 1. Introduction

  ›

  Fear is an unpleasant subjective emotional state that arises when something feels dangerous or threatening. A person in its grip may hyperventilate, feel their heart race, feel choked, dizzy, lightheaded, or notice butterflies in the stomach. In extreme cases the body simply locks up, a reaction researchers call the freeze response. There is one feature that separates human fear from the fear of nearly every other animal. Humans can feel afraid not only of something present or expected, but of events that exist only in the imagination. A child can dread the next ten years, the hereafter, or even just tomorrow. So where does fear come from, and why are some of us so afraid of snakes and heights yet untroubled by flowers and clouds? Why can a parasite turn a rat into a creature that seeks out the smell of cat urine? And why do a handful of people, around 400 of them ever recorded, walk through life unable to feel afraid at all? Those questions lead into the strange machinery of one of the most studied emotions in science.

• 2. A Contested Evolution

  ›

  Fear is often described as a clean product of evolution, but that story is getting harder to defend. The psychological, neurophysiological, and behavioral signs of fear keep turning up in other negative, highly arousing states too, in anger, sadness, disgust, and anxiety. A more scientifically defensible product of evolution may be flexibility itself. That is the capacity to shift bodily states and meet bodily needs through varied behaviors, and later, for humans, through language, by using categories like the word fear. Labeling animal behavior as fear runs into the same trouble. The human observer is always the one imposing the label, and an animal showing something akin to fear is fundamentally exhibiting reflexive defensive behavior. What you read as its fear may simply be its withdrawal, avoidance, or defensiveness. Human fear is therefore bound up with culture, social context, and trait-level differences. Cultural and historical context shapes it directly. In the early 20th century, many Americans feared polio, a disease that can lead to paralysis.

• 3. The Body's Alarm

  ›

  Many bodily changes accompany fear, gathered together under the name fight-or-flight response. This innate mechanism speeds up breathing and heart rate, narrows the peripheral blood vessels so blood pools inward, and dilates the pupils. Muscles tense, including the tiny ones attached to each hair follicle, which contract to produce goosebumps, known more clinically as piloerection. The same surge raises blood glucose, raises serum calcium, and increases a type of white blood cell called neutrophilic leukocytes. Several hormones drive this state. Epinephrine regulates heart rate and metabolism and dilates blood vessels and air passages. Norepinephrine raises heart rate, blood flow to skeletal muscles, and the release of glucose from energy stores. Cortisol increases blood sugar and circulating neutrophilic leukocytes. This primitive system exists for a single purpose, to help an organism survive by running away or fighting the danger. Only after that cascade does the conscious mind register the emotion itself. The physical signs also serve as a message, telling the individual they are afraid and should get away from whatever is causing it.

• 4. Learning To Be Afraid

  ›

  John B. Watson's Little Albert experiment in 1920 showed how precisely fear can be taught. Inspired after he observed a child with an irrational fear of dogs, Watson conditioned an 11-month-old boy to fear a white rat in the laboratory. The fear then generalized to other white, furry things, including a rabbit, a dog, and even a Santa Claus mask with white cotton balls in the beard. A frightening accident can plant fear just as effectively. A child who falls into a well and struggles to climb out may come away afraid of wells, of heights, of enclosed spaces, or of water. You do not even need to suffer the trauma yourself. In a study by Andreas Olsson, Katherine I. Nearing, and Elizabeth A. Phelps, the amygdala lit up both when subjects watched someone else undergo an aversive event they knew awaited them, and when they were later placed in a frightening situation themselves. The capacity to fear, even so, is part of human nature. Certain fears, of animals or heights, are far more common and far easier to induce in the lab than fears of flowers or clouds, a phenomenon called preparedness.

• 5. Fears Of Different Ages

  ›

  From an evolutionary psychology perspective, individual fears may be separate adaptations that arose in different eras. Acrophobia, the fear of heights, may be common to all mammals and may date back to the Mesozoic period. The fear of snakes may belong to all simians and may have developed in the Cenozoic, the still-ongoing era covering the last 66 million years. The fear of mice and insects may be unique to humans, emerging during the Paleolithic and Neolithic, when those creatures became carriers of infectious disease and threats to crops and stored food. Psychologists have sorted the triggers of fear in several ways. Jeffrey Alan Gray named intensity, novelty, special evolutionary dangers, stimuli arising during social interaction, and conditioned stimuli. Archer grouped fear-evoking stimuli into pain, novelty, and frustration, and added looming, an object rushing toward a subject's visual sensors. Russell offered a more functional scheme of six categories, ranging from predator stimuli and physical environmental dangers to stimuli from members of one's own species. Surveys of what people actually fear turn up demons and ghosts, cockroaches, spiders, snakes, needles, social rejection, examinations, and public speaking, with regional fears of terrorism, nuclear war, flying, and clowns.

• 6. Inside The Amygdala

  ›

  The two amygdalae sit behind the pituitary gland, and they are the center of most neurobiological events tied to fear. The thalamus gathers sensory data, the sensory cortex interprets it, and the information flows on to the hypothalamus, the amygdalae, and the hippocampus. When a threat appears, the amygdalae trigger the secretion of hormones that drive fear and aggression and put the body on alert. Once the danger passes, they send the memory to the medial prefrontal cortex for storage, a process called memory consolidation, with the hippocampus recording the surrounding details. In some cases this forms permanent fear responses such as post-traumatic stress disorder or a phobia. MRI and fMRI scans show that in people with disorders including bipolar or panic disorder, the amygdalae are larger and wired for a higher level of fear. The structure can be hijacked. Rats infected with the toxoplasmosis parasite become less fearful of cats and may even seek out their urine-marked areas, behavior that gets them eaten, after which the parasite reproduces inside the cat. The parasite appears to concentrate in the amygdala. Rats with lesions there showed no fear, pulling levers for food even when those levers sometimes delivered electric shocks.

• 7. The Scent Of Fear

  ›

  When threatened, insects, fish, birds, reptiles, and mammals release odorant substances once called alarm substances and now known as alarm pheromones, chemical signals that warn others of the same species. After pheromones were discovered in 1959, alarm pheromones were first described in 1968 in ants and earthworms, then found in mice and rats four years later. In 1985, researchers linked odors from stressed rats to pain perception, finding that unstressed rats exposed to them developed opioid-mediated analgesia. In 1997, bees became less responsive to pain after being stimulated with isoamyl acetate, a chemical that smells of banana and is part of bee alarm pheromone, an effect mediated by an endorphin. By 2004, the location mattered. Pheromone from a rat's face made the recipient sniff or move, while pheromone from the anal area triggered autonomic stress responses such as a rise in core body temperature. Humans appear to send these signals too. A German study from 2006 pooled anxiety-induced and exercise-induced sweat from a dozen people, and some participants could tell the two apart by smell, with the anxiety sweat producing a larger acoustic startle reflex. A 2013 brain imaging study suggested the response can be gender-specific, with female stress sweat producing markedly stronger arousal in women than in men, traced to the right amygdala.

• 8. When Fear Cannot Be Felt

  ›

  Urbach-Wiethe disease is a rare genetic condition that destroys both amygdalae in late childhood, leaving the person unable to feel fear. Since the disease was discovered, there have been only about 400 recorded cases, and a life without fear can carry someone into dangers they would otherwise have avoided. For everyone else, fear can be managed. Cognitive behavioral therapy helps people overcome fear by having them repeatedly confront it in a safe manner, and exposure therapy has helped up to 90% of people with specific phobias to significantly decrease their fear over time. Systematic desensitization replaces the fear response with relaxation through conditioning. Simpler tools exist as well, such as writing down rational thoughts, keeping journal entries, or building a fear ladder by scoring each fear from one to ten and confronting the lowest first. Fear also shapes culture at the largest scale. The Yale philosopher Shelly Kagan, in a 2007 open course, argued that for fear to make sense the feared thing must be something bad, must have a non-negligible chance of happening, and must carry some uncertainty, and that death fails the first two tests. The Roman poet Statius put it more bluntly in the Thebaid, suggesting that fear first made gods in the world.