#rabbithole
Origins of the Six Basic Emotions
August 10, 2024
For decades, we have entertained the sidea that humans have 6 basic emotions: anger, disgust, fear, sadness, surprise, and happiness.
This concept has heavily influenced emotion-related science and innovation, but it seems too simplistic a model of human emotions. Surely we have a lot more emotions than six?
I found it curious that this theory had such widespread appeal in tech, especially in emotion AI. Naturally, I wanted to find out where this theory came from, why it has been so compelling, and the extent of truth it encapsulates.
To save you the trouble, charming reader, I went down the rabbithole myself.
Here is what I found:
Mind as a Sum of its Parts
Humanity's earliest concepts of emotion - and its sister entities such as cognition and perception - are influenced by foundational paradigms of the mind.
Our 18th century understanding of the human mind was quite simplistic. Back then, we thought of the mind as composed of distinct and modular faculties, each responsible for specific mental functions. This “faculty psychology” approach was first put into the collective consciousness by philosophers such as Immanuel Kant (1724-1804), Christian Wolff (1679-1754) and Thomas Reid (1710-1796), but it has trickled all the way into the 21st century as a dominant theoretical framework.
With enhanced neuroimaging technology at our disposal, research advancements, and an incoming paradigm of complex systems thinking, it is becoming more evident that the brain is not made of distinct modules with distinct roles, but instead comprised of distributed networks.
But we still find it deeply tempting to ask questions of the form, “Where in the brain does X emotion exist?". As you can tell, the form of the question implies that the brain functions in a modular way, and that Xₙ emotions exist in n parts of the brain.
As of 2024, we have failed to find sufficient evidence mapping emotions onto brain faculties in any meaningful way. It more so happens to be the case that most parts of the brain light up in some configuration during all of our emotional experiences, supporting the distributed network paradigm.
Universalism and the Evolution of Emotions
Did you know that the first ever recorded emotion recognition study was conducted by Darwin? In fact, Charles Darwin was the first person to use photographs in a scientific publication to illustrate emotional expressions. These photos are bizarre, but they lead to pioneering research in emotion science. Basically, Darwin argued that emotional expressions are evolutionarily adaptive, and that there are certain core facial/bodily expressions that are innate across cultures and species.
In order to demonstrate this, he obtained 11 photographs where people’s faces are electrically stimulated to produce certain human emotions. He then hosted a dinner party with 20 of his friends, and let them discuss how many different emotions they can detect in these faces. While the guests unanimously agreed on a small number of emotions, such as sadness, fear, surprise, and happiness, they strongly disagreed on the more subtle expressions. There are some methodological issues with this experiment, but for 19th century en Darwin’s work goes on to inspire Silvan Tomkins, a psychologist and philosopher who came up with his own theory on the universality of emotion.
And, uh, why do we care about this Tomkins dude?
We care about Tomkins because Tomkins ends up mentoring Paul Ekman, who is the notorious psychologist that goes on to popularize the six-basic-emotions theory.
Feast of the Dead
Paul Ekman hypothesized that if there are universal emotions across cultures, then an isolated people who had never seen emotions of the outside (Western) world will be able to recognize them regardless. In 1960s, Ekman visited a small indigenous community - the South Fore - on the highlands of Papua New Guinea, that had stayed largely untouched by the Western world. Ekman was meticulous in ruling out any possibility of Western influences. His screening criteria for the study subjects included people who did not speak English, never saw movies, never lived in Western settlements or government towns, and never worked for any western missionaries, U.S. scientists, government workers, traders e.t.c.
Ekman was able to gather about 189 adults and 130 children from the South Fore community for his study. His first visit was not too successful due to a lack of proper planning and understanding of the cultural context, but the second time he went, he struck a chord with the locals. Ekman would show the Fore people three photographs and tell them a story, after which they were to pick the photos that they thought fit the story best. In return, Ekman would present them with cigarettes or a bar of soap, which they liked. At the end of the experiments, the locals expressed their heartfelt respect to Paul Ekman in the way that they thought was most honorable, which was to let him know that if he died, they would be happy to eat him. Did I forget to mention? The South Fore people practiced ritualistic cannibalism as part of their funeral customs, whereby women and children would eat deceased relatives as a sign of respect.
As for the results of the experiments, the Fore matched emotional expressions to stories in a similar way as people in Western cultures would do. The only emotion that they did not differentiate between was surprise and fear. Ekman also reversed this experiment slightly, by asking the Fore people to demonstrate facial expressions for certain emotions. These emotional expressions were videotaped and sent to college students in the US, who were able to, for the most part, accurately detect the emotions.
Ekman published his findings in influential journals, and it inspired hundreds of more studies like it. With more and more replicated findings, there came about a widespread consensus that humans display six basic and universal emotions via their facial expressions.
Whether this is actually the case or not is heavily contested in the centuries old universalist vs constructionist debate. Darwin, Tomkins, and Ekman are proponents of the idea that emotions are innate and universal, whereas psychologist James Russell and neuroscientist Lisa Feldman Barrett argue that emotions are socially constructed. Many psychologists and neuroscientists also take strong issue with Ekman's theoretical assumptions and scientific methodology.
Ekman’s theory specifically has received criticism for:
- Using the forced choice paradigm to limit and bias participants responses (James Russell)
- Ignoring the social communication aspect of emotional expression and perception (Alan Fridlund)
- Oversimplifying emotions (Robert Levenson)
- Ignoring the role of language and discourse (Margarett Whetherell)
- Implying/assuming that emotions are universal and biologically fixed reactions rather than constructed when needed (Lisa Barett)
Regardless, Ekman’s theory won the popularity context. The basic emotions theory caught fire and seeped into the public consciousness as an even more simplistic belief. Remember that the basic emotions theory is restricted to the realm of static facial expressions. Sadly in folk psychology, the theory distorts into a generalized statement of the form “there are n basic, universal human emotions.”
A key project that Ekman goes on to develop using this theory is the Facial Action Coding System (FACS), which is an anatomy-based system for describing all visually discernible facial movements. It associates combinations of facial muscles with Action Units (AUs), which are mapped onto emotion states based on muscle contraction and relaxation patterns. It is one of the most widely used system for measuring facial expressions. For example:
- TSA used it to screen passengers in 2007 as part of the SPOT program.
- Pixar used FACS to create more realistic facial expressions in their 2001 film "Monsters, Inc." and subsequent productions.
- It has been used in multiple autism studies since 1990s.
- In 2014, researchers used FACS to study facial expressions in patients with Parkinson's disease to aid in diagnosis and treatment.
- The game "L.A. Noire" (2011) used FACS-based technology to create realistic character expressions.
- Unilever employed FACS-based facial recognition technology in 2011 to analyze consumer reactions to advertisements.
It is clear that Ekman’s theory and the FACS project put order onto the complex and chaotic phenomenon of human emotion. It is certainly not the only theory of emotion out there, but it is one that is simple to explain, and convenient to systemize. In fact, it perfectly fits the supervised machine learning framework and comes at a time when we have facial expression data widely available in image format, which has lead to fueling a lot of early emotion recognition AI.
Sources
The expression of the emotions in man and animals, Charles Darwin (1872)
How emotions are made, Lisa Barrett (2017)
The structure of emotions: Evidence from neuroimaging studies, Lisa Barrett (2006)
Universal Facial Expressions of Emotions, Paul Ekman (1970)
Constants across cultures in the face and emotion, Paul Ekman (1971)
Emotion Experiment: Darwin Correspondence Project (2015)
A functional architecture of the human brain, Lindquist, A., & Barrett, L. (2012)