“As it turns out, facial EMG poses a serious challenge to the classical view of emotion. In study after study, the muscle movements do not reliably indicate when someone is angry, sad, or fearful; they don’t form predictable fingerprints for each emotion. At best, facial EMG reveals that these movements distinguish pleasant versus unpleasant feeling.”

Barrett critiques the classical notion that our facial expressions clearly reveal our feelings, pointing out that facial imaging studies show enormous variation in facial muscle movements and varied connections to our inner emotional states. Context (a person’s collective experience as well as myriad aspects of the current internal and external input) is thus an essential component of interpreting emotional response.

“None of these four meta-analyses found consistent and specific emotion fingerprints in the body. Instead, the body’s orchestra of internal organs can play many different symphonies during happiness, fear, and the rest.”

The author explains that a meta-analysis is the process of combining the results of various studies and analyzing the data they’ve produced. She clarifies that several meta-analyses failed to label certain “fingerprints” for emotions in the human body, and instead, variation was the rule. Again, this illustrates the importance of context in understanding emotions.

“This is one of the most surprising things I learned when I began to study neuroscience: a mental event, such as fear, is not created by only one set of neurons. Instead, combinations of different neurons can create instances of fear. Neuroscientists call this principle degeneracy.”

Barrett introduces the idea of degeneracy, which is the brain’s ability to create the same sensations through different combinations of neurons. Degeneracy shows that the human brain is too complex and varied to simply create the same reactions in the same ways as a response to external stimuli. Universally interpreting emotions is therefore a simplistic and inadequate approach.