Every Halloween, millions of people do something that makes no sense on paper. They queue, pay, and walk into a dark building full of strangers whose job is to make them scream. Then they come out laughing and say: let's do that again.
A group of scientists in Denmark decided to measure exactly what's going on.
The experiment
The team from the Recreational Fear Lab at Aarhus University, led by Marc Malmdorf Andersen, worked with Dystopia Haunted House in Vejle, Denmark. It's a horror attraction with nearly 50 rooms and plenty of jump scares: actors, sudden noises, things that grab you in the dark.
They sent 110 visitors through it, each wearing a heart rate monitor. Cameras followed them through the house, and independent observers scored how each person reacted to each scare. Afterwards, the visitors rated every encounter twice: how scared they were, and how much they enjoyed it.
The answer is a curve
When the researchers put fear and fun on the same chart, they got an upside-down U. Too little fear, and people were bored. Too much, and it stopped being fun and became just unpleasant. In the middle there was a peak.
"If people are not very scared, they do not enjoy the attraction as much," Andersen said, and the same happens when they are too scared. In his words, a "just-right" amount of fear is central for maximizing enjoyment.
The heart told the same story. Big swings in heart rate tracked how scared people were. But enjoyment was linked to smaller ups and downs, again with a sweet spot in the middle. Andersen noticed that this pattern is "strikingly similar" to what scientists see in human play. In other words, a good scare is a kind of game: the body acts as if there's danger, while the brain knows it's safe.
Fear as a vaccine
Mathias Clasen, co-director of the lab, likes to describe frightening entertainment as "a kind of fear vaccine." A small, controlled dose of fear lets you practise staying calm when your heart is pounding, so real-life stress feels a little more familiar.
In 2023, the Swedish amusement park Liseberg teamed up with the same scientists for a 'Peak Fear' experiment. Halloween at Liseberg started in 2015 and has welcomed almost two million visitors. The researchers there described three types of horror fans: people who chase the adrenaline rush, people who are scared but want to beat the fear, and people who use scary experiences to cope with a scary world.
So, how scared should you be tonight?
Just enough. Pick the horror film that makes you grab the cushion, not the one that keeps you awake until Tuesday. If you're dragging a friend through a haunted house, watch their face: a scream followed by laughter means you've found the sweet spot.
And if someone in a white sheet and sunglasses sits next to you at the cinema, stay calm. Science says you're having fun.