People with psychopathy have difficulty empathizing with other people and often harm other people emotionally and physically. Past research has shown that people with psychopathy do not label another person’s facial expressions – for example, “this person is afraid” or “this person is angry” – in the same way that healthy people do.
Could this be because people with psychopathy do not automatically mimic another person’s facial expressions or do not feel other bodily responses to facial expressions?
According to some past research, most people automatically mimic another person’s face when interacting with them. This “mimicry” is sometimes visible to the naked eye. For example, you may copy your friend’s wide-eyed, open-mouthed look as you see and hear them yelping in surprise. But sometimes this “mimicry” is not visible to the naked eye. To measure very small changes in facial muscle activity, scientists use a method called electromyography.
Past research has also found that people tend to momentarily decrease their heart rate and increase the sweatiness of the palms when confronted with another person’s dramatic facial expression. Scientists are interested in changes to heart rate and palm sweatiness (also called “skin conductance”) because they are rough measures of activity in the autonomic nervous system, which regulates the body. The autonomic nervous system can be divided into two branches: the sympathetic nervous system and parasympathetic nervous system. While skin conductance is controlled mostly by the sympathetic nervous system, heart rate is controlled by both branches.
(Some scientists might argue that we can use measures of heart rate and skin conductance as measures of emotion. If you agree with this, then you would want to know if psychopathic people show less change in heart rate and skin conductance when looking at another person’s facial expression, because you would want to know if the psychopathic person is not resonating emotionally with the other person. Some scientists have even called this “affective empathy.” I don’t agree with this, though. We cannot use measures of heart rate, skin conductance, or any other bodily signal as a measure of emotion. The nature of emotion is too complex for us to accurately guess a person’s emotion based on bodily signals. Instead, bodily signals like heart rate and skin conductance tell us something simpler. They tell us how the brain is regulating the body in the moment. But back to the main story.)
In fact, previous studies have found that psychopathic people show less change in skin conductance and heart rate when looking at another person’s facial expression. However, the data are not always consistent, making it hard to draw strong conclusions. And very few studies have tested whether people with psychopathy mimic faces less.
So do people with psychopathy mimic less or feel other bodily responses less so than relatively healthy people?
We tested this question in a sample of 88 incarcerated people with varying levels of psychopathic traits.
We showed participants 6-second long videos of a person making a dramatic, stereotypical facial expression. Stimuli were designed (by another research group) to portray 5 “basic emotions,” including anger, disgust, fear, sadness, and joy. (Note that the idea about basic emotions is hotly debated. Most likely there are not “basic emotions.” And while sometimes people make the expressions below when they are angry, disgusted, and so on, often they do not.)
While participants watched these videos, we recorded their facial muscle activity (using electromyography), heart rate, and skin conductance. After each video, we asked participants what emotion the other person felt, how pleasant or unpleasant the other person felt, and how intensely the other person felt the emotion.
We predicted that psychopathy would be related to lower accuracy for labeling the basic emotion expressions, lower ratings of the other person’s experience of pleasantness, facial mimicry, and reactivity of the autonomic nervous system (changes in heart rate and skin conductance).
But, contrary to our predictions, we found psychopathic traits were unrelated to how people labeled facial expressions, judged the degree of pleasantness the other person felt, mimicked the other person’s face, or experienced changes in heart rate or skin conductance.
Perhaps more surprisingly, we observed that on average the participants in our incarcerated sample did not mimic the other person’s facial expression, regardless of psychopathy. Since we were unable to replicate the basic finding that most people (low in psychopathy) automatically mimic faces, it was difficult to draw strong conclusions about the relationship between psychopathy and facial mimicry from our study.
Our findings did not align with prior studies that found less change in heart rate and skin conductance. Although, if you consider that those prior findings were inconsistent and included several null findings like ours, then our study fits right in.
So, unfortunately, this study does not provide a satisfying answer to the question in the title of this post. But, a single study rarely provides a satisfying answer to such a complex question.
This study has led me to ask new questions about how people with psychopathy integrate information from their own bodies with information from their social environment in order to guide their behavior.
Read the full paper here.
Deming, P., Eisenbarth, H., Rodrik, O., Weaver, S.S., Kiehl, K.A., & Koenigs, M. (2022). An examination of autonomic and facial responses to prototypical facial emotion expressions in psychopathy. PLoS ONE, 17(7),e0270713.