Psychologists have found that we tend to associate our disgusting memories with smells, tastes and touches.
The findings of the study, by researchers at Macquarie University in Australia, and Karolinska Universitet in Sweden, suggest that these sensory cues elicit disgust more intensely than what we see or hear to help protect us from disease.
For the study, a total of 216 university students were asked to complete two surveys, one week apart.
In the first questionnaire, 127 participants were asked to detail their most memorable disgusting, fear-provoking, morally repulsive and gross experiences.
The second questionnaire asked 89 students to fill in the same information, but using experiences that took place in the preceding week.
After recalling these experiences, participants were asked to rate how much each sense—smell, taste, touch, sight or sound—contributed to their effect.
The results suggested that these experiences most commonly featured smells, tastes or touch—the so-called 'proximal' senses—more than sights or sounds, the 'distal' senses.
Researchers in evolutionary psychology hypothesize that the emotion of disgust supports our physiological immune system by making us averse towards sources of infection so that we avoid them. So when we are in the vicinity of something we find repulsive, such as a bad smell, we keep away and protect ourselves from potential harm.
Micheal de Barra—a psychologist at Brunel University London, who was not involved in the present study—told Newsweek: "From an evolutionary perspective, the main function of disgust seems to be to prevent infection. It motivates avoidance of things that might cause illness.
"Infectious disease is a really important selection pressure in evolution: it's shaped behavioral disease avoidance strategies in many animals with examples everything from sheep to ants," he said.
"In humans, we think disgust acts as a cognitive extension of the immune system, motivating avoidance of things that have some possibility of causing infection. It's been termed an 'intuitive microbiologist'."
The universality of disgust is such that the associated facial expressions—like wrinkling up your nose and narrowing your eyes—are widely recognizable. According to research, our ability to recognize someone experiencing disgust also helps us to protect ourselves, as we want to stay away from whatever is causing that person's reaction.
The sensory cues of smell, taste and touch may be more intense elicitors of disgust because pathogens and toxins tend to enter the body at surfaces these senses bind to—for example, the nasal passages, the mouth, or skin.
In contrast, sights and sounds often signal distant potential harms and pose a less immediate threat, the researchers of the new study suggest.
The full findings of the study were published in Royal Society Open Science.
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Update 03/20/24, 6:52 a.m ET: This article was updated with comments from Micheal de Barra.
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