Study: Emotional Stimuli ‘Color’ Different Regions of the Body

Sensation heatmaps created from physical coping responses triggered by emotions. Bodily maps of emotions/Lauri Nummenmaa, Enrico Glerean, Riitta Hari, and Jari K. Hietanen/Dec. 30, 2013/PNAS

What do lukewarm garbage juice, an intimate hug from a close friend, and the sight of a two-year-old child breathing their last breath on a hospital bed have in common? Essentially nothing, except for the fact that they all trigger emotions.

Emotions are argued by many to be at the core of the human experience, yet the scientific community can only objectively define emotions with great ambiguity. Emotions are said to be “complex reaction pattern[s], involving experiential, behavioral, and physiological elements, by which an individual attempts to deal with a personally significant matter or event.”

Emotions Are Functional

There are a number of ways in which experts further define emotions. Scientists agree that emotions are functional, and their definitions diverge from there. Despite the puzzling and subjective nature of emotions, there exists common ground upon which many can agree upon: Garbage juice is disgusting, hugs make people happy, and a dying child is saddening. Not only do these emotions trigger thoughts in our heads, but they often have physical manifestations that validate their functionality.

For example, picture yourself walking through a forest and a mountain tiger suddenly appears in front of you. The fear that you emotionally experience from seeing the beast triggers a number of physiological changes, including the release of cortisol and adrenaline, increases in blood pressure and respiration, and an elevated heart rate. The emotion of fear, therefore, functions as the initiator of a physical chain reaction that tells the body to enter a fight-or-flight mode. While different emotions trigger unique biological pathways in the body, they are also subjective in nature.

Emotions are usually triggered by external events, and often cause physical and biochemical changes in the body that function as mechanisms to cope with external stimuli. With the help of fMRI (functional magnetic resonance imaging) and EEG scanning, scientists have mapped out these changes in cerebral biochemistry that are associated with emotions, and have found that each emotion has a unique image signature.

Can We ‘See’ Emotions?

In one 2013 study, a group of Finnish scientists looked for a way to “see” the body under the effect of emotions from an alternative perspective. They knew that emotions triggered distinct reactions in the brain, so what if there were also distinct reactions in the body?

The researchers set out to examine how six basic emotions (disgust, fear, happiness, sadness, anger, and surprise) and seven nonbasic, complex emotions (anxiety, love, depression, contempt, pride, shame, and envy) stimulate the human body in different ways and to varying degrees. The study subjects were provided with stimuli (such as short stories and films) that depicted the 13 emotions in random order. The subjects were then asked to color in 2D diagrams of the human body to indicate which regions they felt were activated by the distinct emotions.

Interestingly, when shown the same emotional stimuli, most of the participants colored in the same areas on the body chart. The experiment was repeated with participants of Western European and East Asian descent, and both groups responded similarly.

Taking depression as an example, almost all participants answered consistently that their arms and legs were “deactivated” during periods of depression. Looking at envy, we can see that most participants believed the head and chest areas were most affected. Happiness is by far the most powerful emotion, as all areas of the body seem to be thoroughly activated.

Here’s how the average participant characterized body sensations for the 13 emotions:

Blue colors indicate the deactivation of a region, such as a fading/numbing or simply “not feeling that it is responding as much anymore”; red to yellow colors, on the other hand, indicate stimulation and an increase in sensations. Looking at anger, for example, the mouth and hand regions are particularly activated, since the person might be ready to start yelling or throwing fists. Fear seems to trigger a heart-pounding sensation, as that region is glowing the most. Disgust triggers something in the gut—perhaps because garbage juice can make your stomach turn. The more you look at the color maps, the more sense they make.

Sensation heatmaps created from physical coping responses triggered by emotions. Bodily maps of emotions/Lauri Nummenmaa, Enrico Glerean, Riitta Hari, and Jari K. Hietanen/Dec. 30, 2013/PNAS

Implications of the Findings

A physical or other external trigger causes emotions, which then cause physical coping responses, which can be seen in the sensation heatmaps from the Finnish study. Despite this clear correlation, fundamental differences exist in how different individuals interpret physical stimuli—meaning that a specific physical stimulus may be processed differently by different people, based on each individual’s personal experience.

One example would be putting a child and a war veteran diagnosed with PTSD in the same house on the Fourth of July. The local community begins to set off fireworks at 10 p.m., but neither the child nor the veteran knew about this in advance. When the child hears loud explosions in the evening, they might feel excited and want to rush out to see what is happening. But before they can step outside the door, the war veteran grabs the child, runs to the basement, and barricades the two of them in the laundry room.

Embodiment research focuses on how bodily feelings and perceptions influence our emotions and the decisions we make. Let’s take the example above and analyze what happened.

The child and the veteran heard some loud outdoor explosions and saw intense flashes of light. These events, accurately perceived by the two, produce an empirical series of sensations.

The child, upon seeing the flashes of light and hearing the loud explosions, and knowing that it’s July 4, recalls past experiences and assumes that fireworks are being set off nearby. Emotions like excitement and a sense of curiosity may arise that prompt the child to want to rush outside to confirm their assumptions. The war veteran, on the other hand—even though they may be aware of the date—draws from different experiences when hearing and seeing the same physical stimuli. The neurons in the veteran’s brain fire away in search of what might be happening, and might link the event to their past experiences on duty. The veteran, in the same situation as the child, assumes that bombs might be exploding nearby, and experiences fear and anxiety.

Emotional Responses Are Based on Past Experiences

Emotions are subjective, and although research continues to debate which cortex of the brain is involved in which emotion, it is easy to see that emotional responses are underpinned by an individual’s past experiences. The emotional capacity of a baby—rather monotone in their expression—resembles a clean sheet of paper. If external stimuli, such as exploding fireworks, disturb them, then they will likely cry. If they see something that amuses them, such as a rattle, they will likely giggle.

Dr. Paul Ekman, a pioneering psychologist who studies emotions and facial expressions, has theorized that emotions transcend most barriers such as culture and geography, and “prepare us to deal with important events without having to think about them.” Ekman posits that emotions are a coping mechanism for various external and internal events; many are automatic, or “hardwired,” and can’t easily be prevented.

Scientists take many approaches to defining emotions. Dr. Lisa Feldman-Barrett, a distinguished Northeastern University professor in the field of emotional and psychological research, summarizes her findings regarding emotions in the following way: Humans start off with intuitive feelings, such as the state of being calm or agitated, comfortable or uncomfortable, and our emotional capacity increases as we have more experiences. These experiences serve as references for which emotions we should feel in order to best handle certain situations. According to Feldman-Barrett, the child feels excitement because they predict that this state can best prepare them to handle the above situation, and the same goes for the veteran who is fearful, because both are drawing from past personal experiences.

In her TED presentation, she illustrated drawing on past experiences with a seemingly abstract black-and-white image of some seemingly random blobs. No matter how hard the audience tried to make sense of this image, many people were still in the dark. She described the state they found themselves in as “experiential blindness,” where one has no idea how to link the image to a past experience—a process that gives physical or other phenomena a certain meaning. For example, even though the latest smartphone looks like something from outer space, its brand name, its functions, and the mechanical skills required to operate it are still similar to those of previous smartphones, so you can quickly identify that this new object is a phone.

The same is true with emotions. When you see someone smile, with a specific facial structure, you know that they are happy because their face looks a certain way. If you see a close relative smile quite widely but know that they are very sad, it is because you can deduce from past experiences that this person’s face, posture, and expression are combined and iterated in such a way that an intricately nuanced emotion is expressed. These complex perceptions based on experience cannot easily be explained in words because this information is processed by billions of neurons firing simultaneously.

Conversely, if you look at someone and “can’t read their face,” it might be because it is not familiar or you don’t have any related experiences to draw upon. It takes time to learn something new without previous building blocks—like how Feldman-Barrett’s audience struggled with that monotone image. When she showed the same image in color, it became clear what the blobs were—a curled python—and the audience was relieved from their “experiential blindness.”

Her visual demonstration nicely illustrates how emotions are generated. Perhaps you’ve already forgotten when you first experienced fear. However, your experiential neural network has built a foundation over time, so that when you again meet with this emotion, it knows what to do with it; your brain knows which emotion to generate and which signals to send based on experience.

Universal Emotions Trigger the Same Responses

Since humans have certain universal values, we know that a hug from a friend or loved one generates happiness, and that the smell of garbage juice generates disgust. The experiment with the sensation heatmaps illustrates this point, showing us that universal emotions trigger the same responses in the body—although there are no universal brain pathways that trigger emotions. Rather, emotions are generated by processing external stimuli and associating those stimuli to past experiences to see how we reacted then, and the results of those responses. Emotions can therefore be described as a reflex, and they are, ironically, quite logical.

The Finnish study’s mapped-out emotion diagrams are not only pretty to look at, but they also serve as universal indicators of emotions. These colorful maps of the emotional body can also indicate what one doesn’t normally experience. Since the participants in the study had no known emotional disorders, one could take the sensations as a norm. Then, if one experiences emotions differently, it may indicate some form of psychological and physiological anomaly. The researchers note that “topographical changes in emotion-triggered sensations in the body could … provide a novel biomarker for emotional disorders.’

Dr. Robert Backer, with over a decade of experience in research and psychotherapy, says that he has “worked with some people as a therapist who couldn’t describe [their emotions] well … [but] they felt things can allow us to develop vocabulary … [to] more intelligently take action, versus only having a few maladaptive responses.”

This is an important point because the complexity and nuance of emotions often surpass people’s ability to clearly express them in spoken words. Speech contributes to human expression, and while the so-called 7-38-55 rule of verbal and nonverbal communication is perhaps exaggerated and often misinterpreted, spoken language sometimes fails to fully express emotions. Many people visit therapists because they don’t know how to relate or react to unprecedented emotions in their lives.

Suppressing Emotions Is Unhealthy

It is important to note that suppressing and repressing emotions is unhealthy and can cause stress and anxiety. Suppressed and repressed emotions are different in that suppression is voluntary, and repression is involuntary or somewhat subconscious. However, they are both not good for the human body and require appropriate attention. Some people handle this by having a talk with a close friend, other people process emotions by writing in a journal, and some need therapy, depending on what an individual is going through.

Something encouraging drawn from Feldman-Barrett’s work is that the process that generates emotions is not fixed, and there are ways to change one’s thoughts and emotions. She says that “emotions which seem to happen to you are actually made by you. You are not at the mercy of mythical emotion circuits,” meaning that to a large extent, you have the power to change how you feel.

Emotions and thoughts are like dark matter in space, the depths of the ocean, or the quantum realm in physics: We know that they exist, yet understand astonishingly little about them to agree on standard definitions. Perhaps it is not within the reach of today’s science to define emotions, hence the plethora of theories surrounding them. We do know that we don’t have to succumb to powerful emotions because they are, ultimately, generated by us. Knowing that one has the power to change how one feels can be quite empowering for many, especially in these times.