A team of biomedical engineers has mapped the bodily reactions to emotions in 700 individuals and found that patterns were the same, whether the candidate was from Western Europe or East Asia.
The study, carried out by a team from Finland, relies on descriptive feedback provided by candidates from Finland, Sweden and Taiwan. Brain mapping or external sensors could have been used to measure neurological changes and physiological outputs such as sweat and body temperature, but by providing subjects with two silhouettes of the human body and asking them to point out exactly where they felt activity increasing or decreasing, the team could gather intimate data otherwise impossible. It does, of course, mean the study relies on candidates self-assessing accurately and without bias. However, the correlations that arose across cultural and linguistic boundaries provide a strong argument that the subjects did indeed report without bias.
"Different emotions were consistently associated with statistically separable bodily sensation maps across experiments," writes the team in a paper published in the Proceedings of The National Academy of Sciences of The United States of America. "We propose that emotions are represented in the somatosensory system as culturally universal categorical somatotopic maps. Perception of these emotion-triggered bodily changes may play a key role in generating consciously felt emotions." The authors are here suggesting that these bodily impulses, when felt, drive the emotional reaction to the surface more forcefully -- as we begin to associate a rapid heartbeat with fear, for instance, that rapidity makes us fearful.
The team carried out a series of experiments during which candidates were subjected to words, movies, facial expressions and short stories online, all designed to instill different basic and complex emotions. The emotion was never directly uttered in the medium used, so as not to bias the results. The subjects were then asked to colour in the silhouettes in the areas of the body where they experienced an increase (in red and yellow) or decrease (in blue or black) in sensitivity. They were not asked to identify places where they felt a physiological output, such as a rapid heart rate or a rising temperature. Instead, the team was looking for an instantaneous reaction that could be consciously identified by the participant.
They found that certain emotions could be grouped together, in terms of bodily reactions. For instance, as is clear in the picture, anger, fear and anxiety were each associated with increased activity in the chest area and upper body. A tightness in the chest can be associated with these negative emotions, as well as an increased heart rate. Pride, however, inspired increased activity in this area but also in the head.
Anger centred partially on the arms, perhaps indicating the fight response. In direct contrast, feelings of shame, sadness and depression are linked to decreased sensitivity in the limbs, suggesting the individual feels a sense of weakness that typifies those emotions. With depression in particular, the chest is black and the limbs blue -- the physical image painted by the candidates is one of an emotional powerlessness represented by physical powerlessness. With surprise, the arms and legs are also black and blue suggesting the individual temporarily feels frozen to the spot, while contempt is typified by a mainly black body from the upper chest down and increased activity in the neck is clear for disgust. As one might expect, happiness is represented as total increased activity across the whole body, with love is depicted very similarly, aside from the apparently numb legs.
All emotions triggered a sensation in the head area, the authors explain, "reflecting probably both physiological changes in the facial area (i.e., facial musculature activation, skin temperature, lacrimation) as well as the felt changes in the contents of mind triggered by the emotional events".
The team found that basic human emotions correlate to reactions in certain parts of the body in a "categorical manner", in line with results from prior brain imaging and behavioural studies and across the Finnish, Swedish and Taiwanese candidates. The study featured subjects from three different countries partially in order to rule out linguistic associations that could temper the results -- something that could yet still prove a problem for the findings. For instance, the authors point out that phrases such as "cold feet" or "heartbreak" could provide a conceptual groundwork for individuals who then adopt -- or perceive their bodies to adopt - the same physical attributes when they experience the corresponding emotion. This argument would make sense, considering the above findings -- decreased activity in the legs for love may correspond to the expression "legs go to jelly"; decreased activity in the limbs for fear (depcited as black) may correspond to the expression "frozen in fear".
The fact that the results across all three nationalities highly corresponded with one another is however, according to the authors, proof that this argument is incorrect: "Bodily sensation maps likely reflect universal sensation patterns triggered by activation of the emotion systems, rather than culturally specific conceptual predictions and associations between emotional semantics and bodily sensation pattern." If they are wrong, the authors note, then they ask where these conceptual associations originated from, considering they can cross linguistic and cultural boundaries. Did the phrases perhaps arise because the sensations were commonly prevalent?
Understanding the link between bodily sensations and emotions could open the door for treating a whole range of emotional disorders. The authors suggest for instance that the map could help in developing biomarkers for different disorders. It is possible it could also play a role in recovery -- the facial feedback hypothesis, for instance, suggests emotions can be modulated by changing our physical reactions. It's why some believe smile therapy can ease symptoms of anxiety.
"Unravelling the subjective bodily sensations associated with human emotions may help us to better understand mood disorders such as depression and anxiety, which are accompanied by altered emotional processing, automatic nervous system activity and somatosensation," write the authors.
They recognise that the sensations are only part of the story, but could play a part in unravelling emotional experience. To do that, they would need to eventually rely on more than self-reporting. They suggest that in the future we could try measuring whole-body prefusion, recording changes in blood flow in subjects when they feel particular emotions. This would enable us to separate actual physiological changes from our own bodily perceptions, perceptions that could be subject to bias the Finnish team could not possibly measure or account for.