In the study, 500 participants were asked how much they enjoyed different examples of sweet, sour, salty, and bitter foods. Then, they were asked to take a series of personality assessment quizzes to evaluate their aggression, each of the Dark Triad measures (narcissism, psychopathy, and Machiavellianism), everyday sadism (verbal, physical, and vicarious), as well as Big Five personality traits, which include extraversion, agreeableness, conscientiousness, emotional stability, and openness. The researchers found that people who liked bitter foods were also more likely to score highly in measures of psychopathy, sadism, and aggression. In fact, they write, an affinity for bitter foods was a better predictor of personality than any of the other tastes. “Taken together, the results suggest that how much people like bitter-tasting foods and drinks is stably tied to how dark their personality is,” the study authors write. This study adds valuable information to the little-explored question of how personality relates to taste preferences (though researchers have already found that people who are open to new experiences eat more vegetables and fiber, and those who are “sensation-seeking” drink more caffeine). But as the researchers themselves point out, understanding what makes a person like a particular food is a complex knot of biology and psychology, influenced by her sensitivity to tastes and odors as well as past experiences. The researchers even had trouble deciding which foods to use as examples for bitterness because different people describe the tastes differently. And although the study makes a good case for a correlation between “dark personalities” and a preference for bitter flavors, it doesn’t provide any information about what might cause that preference—is it biology or psychology, or both? Though the researchers don’t mention any intention to conduct any future studies to explore the cause of these preferences, that information might be even more valuable than the study at hand.