Why Do We Love Whodunits Like "Glass Onion"?

Riding high on Rotten Tomatoes with, at the time of writing, a 94 percent critics and 93 percent audience score, “Glass Onion: A Knives Out Mystery” was written, produced and directed by self-confessed Agatha Christie superfan Rian Johnson. Crime fiction fans and writers have long known that there is a formula to creating a good whodunit mystery, proven by Christie—who to this day has sold more books than anyone other than Shakespeare and the Bible.

In other words, Johnson must be getting something right. Some recent psychological studies may offer some real insight into why people go mad for a mystery.

It is not offering a spoiler to point out that, like Agatha Christie’s stories, Johnson's story offers his audience characters to love, including the New Orleans-accented Daniel Craig as world famous detective Benoit Blanc, and characters we love to hate, which include nearly every other character in “Glass Onion.” You could say most of the characters play off of stereotypes of the more odious public figures in Western culture, including a billionaire character based on a real-life rich man everyone knows. Johnson very smartly knows that the audience will find these characters' behavior gross—and according to studies, disgust is exactly what drives audience interest in mysteries.

Many psychologists consider disgust to be one of the basic emotions coming from our evolutionary core (though this theory is actively being challenged). The evolutionary psychology story of the feeling is that it serves the purpose of protecting us from spoiled food and poisonous items with a visceral feeling that moves us to reject, avoid, get away.

A fun new study demonstrates that if crime TV episodes open with "gross-out" graphic images of the murder victim, a majority of viewers will find the story more compelling, and therefore more rewarding and enjoyable when the killer is caught. Marcus Wardley based his research on psychological theories of disgust, including the most well-known evolutionary argument that disgust comes out of a self-preserving aversion to tasting dangerous, bitter items that are poisonous.

The study picks up an old question: Why do people like getting horrified or grossed-out? At least with crime shows, according to the study, the answer is: It feels so good when the hurting stops, and justice is served.

Study participants viewed clips of the TV show "Bones," some watching a full serving of disgusting clips while others watched the same story clips, but with the disgusting images edited out. Based on viewer questionnaires, Wardley was able link initial feelings of disgust to greater pleasure with the story’s resolution.

In other words, according to Wardley, the more you are initially disgusted with crime scene imagery, the more serious and threatening you take the crime, and the more pleasure you feel when the bad feelings stop. From these results, Wardley was even able to offer some advice to crime writers: “I recommend that scenes eliciting physical disgust be directly related to the crime, and if the crime is not resolved, any scenes involving disgust should be omitted.”

Moral Disgust and Gross Characters in Mystery Stories

You’ll notice that Wardley confines the scope of his research to content that is physically disgusting—the visceral, gross-out feeling that comes from seeing a decomposing corpse. But what role, if any, does disgust play in crime fiction that isn’t graphic at all, such as the “cozy” mystery or whodunits like Agatha Christie’s work, or "Glass Onion"?

One of the rules of story established from the Golden Age of Detective Fiction is to never show blood and gore—precisely the disgusting stuff of Wardley’s study. But there’s another kind of disgust that likely plays a role in whodunits: moral disgust, or the repulsive reaction the audience feels toward those off-putting elements of characters who are selfish, mean, greedy, immoral, and generally unkind.

Taylor and Uchida, in a recent study, explored the differences among horror, fear, and moral disgust. They find that horror is a particular emotional response we have to graphic depictions of harm, which we then follow with a “moral disgust with the harm’s causal agent.” They define moral disgust as a strong emotion, explaining that we react with moral disgust to “potentially harmful people” who show “traits associated with bad character” which may harm “other people (or) society” (p. 347).

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We can infer from this that moral disgust is more emotion based, than a body- based feeling like visceral disgust. Moral disgust is an emotion we feel about potential harm, and how we perceive others in our group to be acting in potentially harmful ways.

Now imagine a group of unsavory characters, each a suspected murderer, stuck together on a remote island—as Christie wrote in her novel And Then There Were None and Johnson gave us in “Glass Onion”—and you’re getting the idea. Whodunits may be neurologically compelling to us when they have elements in common which pull on our moral strings, including:

1. A likeable detective who may play slightly naïve to the suspects.
2. A sympathetic loved one or friend of the victim who seeks justice.
3. A group of suspects who show character traits including being selfish, mean, or greedy.
4. Combine everyone into a confined space, such as a remote country mansion on a stormy night, or a train stuck in the snow, on a yacht, or on a rich man’s remote island with no boat access. Shake and serve.

By working with the conclusions of these studies, we can venture to say that there are compelling psychological explanations for why we love to hate unkind characters, and how we are driven to see justice served—so much so, that we just can’t look away until the fun over.