Taking your coffee black in the morning, or ordering a gin and tonic at happy hour, can reveal a lot more about you than just your drink preferences. According to a recent study published in the journal Appetite, a liking for bitter-tasting foods and drinks can be a sign of dark personality traits, including Machiavellianism, sadism, and narcissism.

Eating preferences can be a doorway to your personality. Smell and taste is processed in the brain’s limbic system, which consists of a network of connected structures near the middle of the brain within the central nervous system. These structures work together to affect a wide range of behaviors, including emotions, motivation, and memory. It specifically deals with instinctive or automatic behaviors.

Christina Sagioglou, study author and psychologist at the University of Innsbruck in Austria, and her colleague Tobias Greitemeyer, sought to investigate how bitter taste preferences may be associated with antisocial personality traits. Approximately 1,000 people with an average age of 35 were analyzed in two separate experiments.

In the first experiment, 500 men and women were shown a long list of foods with equal numbers of sweet, salty, sour, and bitter foods, such as chocolate cake, bacon, vinegar, and radishes. They were asked how much they liked each of them on a six-point scale ranging from "dislike strongly" to "like strongly." Then, the participants were told to complete four separate personality questionnaires that measured their levels of aggression by asking them to rate statements that resonated with them, such as “Given enough provocation, I may hit someone.”

For the second half of the experiment, participants were asked to rate how strongly they agreed or disagreed with statements that assessed personality traits of Machiavellianism, psychopathy, and narcissism. For example, these sections included “I tend to manipulate others to get my way,” “I tend to be callous or insensitive,” and “I tend to want others to pay attention to me.” The participants were also asked to answer questions relating to the “big five” personality traits: extraversion, agreeableness, conscientiousness, and emotionality stability. Everyday sadism was assessed by the Comprehensive Assessment of Sadistic Tendencies.

Similar to the first, the second experiment assessed their preferences for food tastes, except the list was reduced to 20 items — sweet and bitter. The participants also had the choice to choose “I don’t have an option” to each of the food items. This was done to investigate divergence from the food-specific preferences and general taste category ratings. For example, drinking coffee with sugar and milk successfully masks most of its bitterness.

Based on both experiments, the researchers concluded bitter taste preferences were linked to malevolent personality traits. “General bitter taste preferences emerged as a robust predictor for Machiavellianism, psychopathy, narcissism, and everyday sadism,” wrote the researchers.

They also found that for people with sadistic traits, the consumption of bitter foods was comparable to a rollercoaster ride, where they enjoyed things that induced fear, according to Sagioglou. This concept was first introduced by psychologist Paul Rozen in the 1980s, who described everyday sadism to benign masochism, or the enjoyment of painful activities.

Similarly, a 2013 study published in the journal Food Quality and Preference, found personality plays a significant role when it comes to your lust for heat or spice in your food. People who were more likely to enjoy movies or seek adventure were about six times more likely to enjoy the burn of a spicy meal. As previously described by Rozen, there’s a correlation between liking roller coasters and liking spicy food because of the thrill.

So, perhaps our favorite food and drink order says a lot more about our personality than we think.

Sources: Sagioglou C and Greitemeyer T. Individual differences in bitter taste preferences are associate with antisocial personality traits. Appetite. 2015.