Want to travel back in time? In our weekly “Retro Science” series, we’re digging up visual artifacts that capture fascinating moments from science history, including surprising studies, outdated inventions, and breakthrough achievements. By recapturing science’s impressive feats and most amusing flops, RetroScience will remind us of how far we’ve come, and how far we have yet to go.
We all know that Charles Darwin is the father of evolutionary biology. What is less known is that he was also an early experimental psychologist. In 1872, Darwin published The Expression of the Emotions in Man and Animals, in which he theorized that both humans and animals show emotion through similar behaviors. He corresponded with many scientists to develop this work, including French physician Guillaume Duchenne de Boulogne, shown in the photo above. He was particularly interested in a series of slides from Duchenne, which show him applying electrical currents to the face of an old man, stimulating different facial muscles to form emotional expressions. Don’t worry about the man – Duchenne reassured concerned critics that the subject had an anesthetic condition, which prevented him from feeling any pain from the electric shocks.
Based on his findings, Duchenne concluded that the human face expressed at least sixty different emotions, each determined by different muscle contraction combinations. However, Darwin speculated that only a select few of Duchenne’s slides expressed genuine human emotion. To test this idea, he arranged Duchenne’s slides before twenty dinner guests and asked them which emotion they perceived for each slide. Darwin’s guests agreed almost unanimously about certain emotions such as happiness, sadness, fear and surprise, but strongly disagreed about more ambiguous slides, suggesting that humans may perceive a select variety of emotions.
For a small sample size, Darwin’s experimental home test was surprisingly on point. Today, many psychologists agree that certain emotions are universal to all humans, regardless of culture: anger, fear, surprise, disgust, happiness and sadness. Darwin’s methods have also been reapplied in modern psychology experiments to study emotional recognition in psychiatric diseases, like autism and schizophrenia. To learn more about this electrifying experiment, read here.