Barrett explains that, historically, people have understood emotions to be “built-in from birth,” which she refers to as the “classical view of emotion” (iii). According to this perspective, external events prompt our emotional neural circuits to activate, which then subjects us to experiencing particular emotions. The classical view of emotion posits that emotions are primal traits that we evolved to aid our survival and that they’re universally present in all people. Barrett notes that Western civilization perceives emotions as primitive impulses that work in contrast to rationality; this view is a recurring theme in our society.

Barrett claims that while this view may be popular, it’s not founded in concrete evidence. She acknowledges that many studies have demonstrated that the classical theory is accurate, but points to hundreds of other studies that show the opposite. The author writes that no study has conclusively proven the existence of a biological “fingerprint”—that is, specific neural pathways, or physical responses, to each emotion. Instead, people can experience the same emotion but have different brain and body reactions. For example, one angry person may experience increased blood pressure and make an angry facial expression, while another equally angry person may not.