Witches, ghosts and ghouls of all kinds will be prowling the streets of Madison this Halloween in a celebration of spookiness. Whether you’re planning to dress as a fairy princess or spend the night watching horror movies, we can all expect to be spooked in one way or another. But what exactly is fear? When we feel that spike of terror, what’s happening to our bodies? Are humans the only ones that feel fear?
The definition of fear is contested, but for our purposes, fear is a state of being influenced by both our surroundings and our response to them. For example, in a haunted house, our state of fear is influenced by both the thing that scares us (the evil clown popping up from behind the wall) and our reaction, which can include fight (punching the clown in the face), flight (running out of this creepy haunted house) and freeze (you are now stuck in the haunted house forever).
An important fear factor is what parts of our brain are processing the experience. The difference between feeling truly terrified and getting a rush of fear from a horror movie has to do with our “thinking” brain and “feeling” brain. Fear is first processed by the amygdala, an almond-sized region in your brain that starts sending signals to the rest of your brain and body. The amygdala also releases stress hormones and begins preparing for a defensive response.
The amygdala is connected to the hippocampus, which, in combination with the prefrontal cortex, processes the situation and greatly influences your fear response. For example, there’s a difference between seeing a clown at a haunted house and seeing a birthday clown. In the circumstances of the haunted house, the hippocampus and the prefrontal cortex register the situation as dangerous, and you’ll likely feel the effects of fear. In the case of a birthday clown, the hippocampus and the prefrontal campus dampen your fear response, making sure you don’t run away from (or tackle) the birthday clown, unless it’s a murderous terrifying horror birthday clown.
Humans are not unique in the experience of fear. Herbivores living on the savannah show heightened fear responses during the full moon. This is an adaptation to the fact that lions have greater visibility on bright nights, giving them an advantage when stalking prey across the grasslands. Or maybe werewolves.
We know that mammals and vertebrates feel fear, but what about bugs? There isn’t a clear answer. There’s no reason bugs and invertebrates don’t, but our understanding of their emotions is fuzzy. Because these creatures are built so differently than us, we often struggle to decipher their responses. It is very funny, however, to imagine a terrified spider running away from a clown. Scuttle! Scuttle away from the clown, ye eight-legged fiend.
Feeling fear can sometimes make us upset — it’s not always a fun feeling to have. But, just like all negative emotions, fear exists in our bodies to serve a purpose. It keeps us safe. So, the next time you see a sock that looks a little too much like a giant rat and jump out of your skin, thank your amygdala and its buddies — they’re doing you a service.