Disgust Learning

One line of research in our lab asks the question, "How do we learn and unlearn disgust?" In one sense, all disgusts are learned. As much as feces, vomit, or gore might seem intrinsically disgusting, we require years of socialization to become disgusted by these stimuli.To the horror of parents around the world, children lack an innate tendency to avoid gross things, in particular, to avoid putting them in their mouths (which is the primary thing disgust keeps us from doing). Anthropologists have found that feral children exhibit virtually no disgust, because there is no one around to teach them which substances are offensive and should not be put in their mouths.

Our research is focused on pinning down one mechanisms by which disgust spreads, associative learning, which can be studied using variants of Pavlov's classical conditioning procedure. In particular, we are interested in how a trait known as disgust sensitivity, which encompasses how easily one is grossed out, determines how easily one acquires (and how stubbornly one retains) new disgusts. This research has implications for a broad range of important human phenomena, ranging from eating (e.g., intolerance of foods in food neophobia) to discrimination and prejudice (e.g., intolerance of immigrants in xenophobia) to anxiety-related disorders (e.g., intolerance of germs in OCD).

If you would like to know more about this research, check out these papers:

Armstrong, T., McClenahan, L., Kittle, J., & Olatunji, B. O. (2014). Don’t look now! Oculomotor avoidance as a conditioned disgust response. Emotion, 14, 95–104.

Armstrong, T., & Olatunji, B. O. (2017). Pavlovian disgust conditioning as a model for contamination-based OCD: Evidence from an analogue study. Behaviour Research & Therapy, 93, 78–87.

Disgust habituation

In conducting our research on disgust learning, we stumbled over an interesting finding. With repeated exposure to a disgusting image, participants actually look less and less at the image. This increasing 'oculomotor avoidance' (which we measure with an eye tracker) goes against the psychological principle of habituation, which holds that a stimulus should evoke a weaker response as it becomes less novel. Our lab believes in habituation--it's one of the few law-like principles in the aspiring science of psychology. In fact, you can see habituation at work in much simpler organisms that probably don't have a psyche (no offense, sea slugs). Thus, we set out to see how many repetitions of a disgusting image it would take to observe the law of habituation. We have now grossed out over 100 participants with a total of over 5000 disgusting image presentations, and we are yet to observe a decline in oculomotor avoidance of disgust! What's going on? We're still trying to figure that out, but we think this finding has important implications for understanding disgust and its distinction from other negative emotions, like fear. Also, it might have implications for why exposure therapy is less successful in some patients with disgust-based aversions. Finally, we might need to rethink our understanding of oculomotor avoidance. Perhaps it's not a passive response, but instead an instrumental behavior, and thus it might not undergo habituation. We often take terms like "response" and "behavior" for granted, but they were once the site of epic battles in behaviorism. To figure out what's going on, we're taking a deep dive into old school learning theory.