The Neuroscience of Fear: What Happens in Your Brain When You're Afraid

What happens in our brain when we are afraid? Plus, is fear innate or learned?

Sabrina Stierwalt, PhD
5-minute read
Episode #212

In 1920, psychologists found empirical evidence that fear can be learned in what is known as the Little Albert experiment. An otherwise emotionally stable 9 month old baby referred to as “Albert” was conditioned to be afraid of furry objects in much the same way Pavlov experimented with dogs. Every time the child was given a white rat to play with, the experimenters banged loudly on a steel bar with a hammer from a position out of the baby’s sight. The poor child, who was previously unafraid of the rat, soon became very distressed every time the rat was reintroduced. Little Albert even appeared to transfer this fear to other furry objects, including a rabbit, a seal-skin coat, and the beard on a Santa Claus mask.

If you are appalled by the idea of terrifying a baby in the name of science, rest assured that such an experiment would never pass an ethics test now. Modern standards do not allow tests with such a high risk of long term psychological damage. Also, although of course less importantly, the experiment was not designed to include a control subject for comparison, nor did any follow up occur with Little Albert after the experiments ended when he was ~ 1 year of age.

Our fears can also depend on personal childhood experience. For example, a child who has been attacked by a dog at a young age may continue to be afraid of dogs later in life. When our emotions run high, the chemicals released by our brain can work to build stronger memories of the situation, like vivid snapshots of our surroundings at the time. This is the same effect at work when we remember exactly where we were or what we were doing the moment we hear at item of bad news.

So if we can be conditioned to fear certain things, our cultural upbringing must dictate to some extent what we are afraid of. Fears often play on the same theme, like the unnatural, but those unnatural beings may take on different forms, whether it be the undead, demons, or ghosts and will vary with geography and over time.

For example, in Central and South America stories of the chupacabra, a beastly creature that feeds off the blood of livestock, have been common since the first reported sighting in Puerto Rico in the mid 1990s, but the spiny, reptilian creature is not well-known in other countries.

Culturally influenced fears change over time as well. Earlier horror films, for example, would have been considered frightening due to subtle use of confused perspective (like The Cabinet of Dr Caligari in 1919) or shadow and light (as in Nosferatu in 1922. Now that directors have many more tricks up their sleeve including CGI and, well, color, audiences demand a lot more from their scary visual effects. Dating back even farther, freak shows were also once considered scary. Audiences were dared to look upon human oddities like bearded ladies or so-called “living dolls”.  Thankfully, the idea of gawking at someone because they are different is pretty appalling by today’s social norms.

What are people's top fears?

A now dated 2001 Gallup poll of > 1,000 adults in the US found that the most commonly held fear (51% of participants) was the fear of snakes. (I agree!) Public speaking, heights, confined spaces, and spiders/insects rounded out the top five fears. Responses also varied by gender, with women being more likely to be afraid of reptiles and insects but men being more likely to fear going to the doctor, and by race, with white people being more afraid of public speaking than people of color, for example.

A more recent (but less controlled) crowd-sourced survey conducted by Yahoo of > 20,000 volunteers amongst its users found slightly different results 14 years later. The top three phobias were acrophobia (fear of heights), arachnophobia (fear of spiders), and claustrophobia (fear of enclosed spaces). Also in the top ten: thalassophobia (fear of deep water), glossophobia (fear of public speaking), and trypanophobia (fear of needles).  Trypophobia (the fear of objects with irregular patterns of holes) and lepidopterophobia (the fear of butterflies) were also in the top 20.

Whether you enjoy being scared or not, have a happy and safe Halloween and check out my earlier episode on what experiments you can do with all of that leftover candy!

Until next time, this is Sabrina Stierwalt with Ask Science’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Ask Science on Facebook or follow me on Twitter, where I’m @QDTeinstein. If you have a question that you’d like to see on a future episode, send me an email at everydayeinstein@quickanddirtytips.com.

Images courtesy of shutterstock


Please note that archive episodes of this podcast may include references to Ask Science. Rights of Albert Einstein are used with permission of The Hebrew University of Jerusalem. Represented exclusively by Greenlight.

About the Author

Sabrina Stierwalt, PhD

Dr Sabrina Stierwalt earned a Ph.D. in Astronomy & Astrophysics from Cornell University and is now a Professor of Physics at Occidental College.