Inside 7 Of The Most Horrific Psychological Experiments Ever Performed

Published June 20, 2023
Updated December 23, 2024

The Landis Facial Expression Experiment (1924)

Landis Facial Expression Experiment

RedditCarney Landis’ psychology experiments took a dark turn when he had his subjects decapitate rats.

In the early 1920s, psychologist Carney Landis found himself wondering if all humans made the same facial expressions when responding to the same emotions. He wanted to find an answer to this question, but there was one major hangup: Landis didn’t believe that people could intentionally replicate the faces that they make when they’re truly experiencing certain emotions.

So, according to Gizmodo, Landis sought to evoke genuine emotions in his test subjects, and then photograph their faces to analyze their expressions.

But rather than evoking positive emotions in his subjects — say, happiness, laughter, or curiosity — Landis wanted to capture the expressions that they made when they felt negative emotions in his psychology experiments.

He drew lines on his subjects’ faces in marker, and then created situations in which they would experience fear, pain, disgust, and sadness. For example, he would shock his subjects to capture a photograph of them in pain or disgust them by making them stick their hands into a bucket of live frogs.

But these experiences paled in comparison to Landis’ final test. At the end of the psychology experiment, Landis would give the subject a rat and instruct the person to behead the rodent. Naturally, some subjects assumed that he was joking or testing for some other expression, such as confusion.

But Landis was not joking. He again ordered his test subjects to decapitate the rat in front of them. If they refused, he would do it for them while they watched — as their horrified expressions were captured on camera.

Not only was this incredibly cruel, but it also didn’t yield any particularly groundbreaking results. His conclusion was that the natural expressions people made “showed great differences among themselves. In some cases where it was expected, no expression of emotion was present at all.”

author
Austin Harvey
author
A staff writer for All That's Interesting, Austin Harvey has also had work published with Discover Magazine, Giddy, and Lucid covering topics on mental health, sexual health, history, and sociology. He holds a Bachelor's degree from Point Park University.
editor
Maggie Donahue
editor
Maggie Donahue is an assistant editor at All That's Interesting. She has a Master's degree in journalism from Columbia University and a Bachelor's degree in creative writing and film studies from Johns Hopkins University. Before landing at ATI, she covered arts and culture at The A.V. Club and Colorado Public Radio and also wrote for Longreads. She is interested in stories about scientific discoveries, pop culture, the weird corners of history, unexplained phenomena, nature, and the outdoors.
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Harvey, Austin. "Inside 7 Of The Most Horrific Psychological Experiments Ever Performed." AllThatsInteresting.com, June 20, 2023, https://allthatsinteresting.com/psychology-experiments. Accessed February 28, 2025.