New Finding: Differences Between Facial Expressions and Emotion in Frontotemporal Dementia and Related Disorders
“Suit the action to the word, the word to the action…”
-Hamlet to the players
When you experience an emotion, several parts of you react at once. Emotions usually involve automatic, synchronized coordination of facial expressions, physiological changes, and subjective experience.
Let’s say you bite into a delicious apple—your eyes close, a smile spreads across your face, the parts of your nervous system associated with pleasant digestion kick in, and you think something like, “oh, yum.” Bliss.
Now you look at the exposed white of the apple and see half of a green worm wriggling in the part you just chomped. Your nose crinkles, your gut twists, and you say something like “blech!” Disgust.
We also rely on this when interacting with other people. Except in unusual circumstances, we tend to assume someone crying feels sad and someone smiling feels happy, and we respond to them accordingly. Sometimes, though, what someone seems to feel and what they truly feel is disconnected. Play acting is one example, as is a deliberate lie.
Neurological diseases can also disconnect how we appear and how we feel. A well-known example is pseudobulbar affect, also known as pathological laughing or crying, when someone laughs or cries for little or no reason. This can be caused by several illnesses, including multiple sclerosis or amyotrophic lateral sclerosis.
Working with the Berkeley Psychophysiology Laboratory, we recently investigated the connection between facial expressions and self-reported emotional experience in frontotemporal dementias. Frontotemporal dementias can be associated with social dysfunction, and we wondered if a disconnection between emotional appearance and experience might play a role in that dysfunction.
We did find such disconnections between facial expression and self-reported emotional experience—for example, people with the behavioral variant of frontotemporal dementia (bvFTD) move their faces less in the way one might expect when shown a sad, amusing, or disgusting film clip, despite reporting a similar emotion to people without any known neurological condition.
There are several possible explanations for this. Possible explanations could include less ability to move the face appropriately, less awareness of their own internal state, or less ability to accurately report on their own true internal state. However, exploratory analyses of each of these possibilities were unrevealing.
This reminds us that bvFTD symptoms widely vary from person to person. While collectively this disconnection may be present, each person may have it for a slightly different reason, and some may not have a disconnection at all. Whatever the cause, these results suggest a need for caution when interpreting how someone with bvFTD “really” feels.
Results were recently published in The Journal of Neuropsychiatry and Clinical Neurosciences. You can access the paper here.