HealthTalk: Emotions

Cognitive and biological bases of generating emotion are still debated. (credit: Courtesy of Wikimedia Commons) Cognitive and biological bases of generating emotion are still debated. (credit: Courtesy of Wikimedia Commons) Credit: Maria Raffaele/Art Editor Credit: Maria Raffaele/Art Editor

Happiness, sadness, fear, pride, curiosity, and empathy: These are all examples of emotions that, in many ways, show who we are. They influence our decisions and give us a personality that is distinct from anyone else’s. As a result, many theories attempt to describe and explain emotions. However, because the cause, duration, and intensity of emotions can vary greatly, it has previously been hard to create a unifying theory.

According to, the concept of an emotion can be broken down into three component parts: Subjective feelings, physiological responses, and expressive behavior. Because subjective feelings are just that — subjective — these can be difficult for scientists to quantify. In contrast, physiological responses can be measured as increases in heart rate or the release of chemicals in the body.

Studies in neurobiology have shown that the limbic system of the brain is involved in producing emotions, which are responses to either pleasant or unpleasant stimuli. The brain produces certain chemicals that cause the physical effects of emotion. One chemical, for example, is adrenaline, which causes increased heart rate, breathing rate, and blood flow and prepares people for stressful situations. Another is serotonin, which has been observed to increase when a person is experiencing feelings of happiness and love.

In addition, emotions are expressed outwardly in the face — the limbic system controls the subconscious movement of facial muscles that express certain emotions. As a result, we do not have to think about smiling when we are happy; we just smile.

Emotions likely evolved to improve our survival ability. According to, the purposes of emotions are motivation to act, generating internal signals, and generating social signals. The emotion of fear is an example of motivation — when we feel fear, we move away from whatever unpleasant stimulus is causing the fear, while physiological changes in our bodies facilitate this movement.

Internal signals can be created when making decisions — if the decision contradicts knowledge gained from experience, an unpleasant emotion may be triggered, which will compel us not to make that decision. For example, if a certain restaurant caused a person to get food poisoning, making the decision to eat at that restaurant again will generate a negative emotion in that person.

Social signals arise from the effect that emotions have on our body language. Seeing someone with an expression of happiness will make him or her seem more approachable than someone displaying outward anger or disgust. In this way, emotions dictate how people behave towards each other.

When trying to connect emotion with physiology, one of the most accepted models of emotion is the “two-factor theory,” which was proposed in 1962. This model states that generating emotions requires both a physiological stimulus as well as an understanding of that stimulus. For example, to be afraid, we must understand that the stimulus may be dangerous. Arriving at this model did not happen quickly, however. One of the earliest theories on emotion is the James-Lange theory of emotion, which was proposed in 1884. It states that emotions happen as a result of experience, according to However, scientific experiments have shown evidence that contradicts this theory. This theory was challenged by the Cannon-Bard theory, which proposed that emotions and physiological reactions occur in conjunction. However, many criticized this theory because it made it seem as if emotions were generated spontaneously, without any biological mechanism.

The difficulty in arriving at a theory that explains emotion reflects its complexity. To generate an emotion, we must understand the stimulus that caused it and compare it to our past experiences to determine if the stimulus is harmful or not. Then, the brain must secrete the correct chemical to produce the correct response in our body. The study of emotions is ongoing, and discoveries will lead to further insight in the mechanisms of the brain.