In the past, it was said that the eyes were the mirror of the soul. In fact, even today many people try to uncover a lie by asking the other person to look them directly in the eyes. However, is this just a popular myth or can our eyes really speak for us?
Science has discovered that our pupils can send many signals to our interlocutor, we just need to know how to scrutinize those black spots.
What signals do the pupils send?
- You are thinking about something complicated
In 1964, psychologists at the University of Chicago recruited a group of people and asked them to solve different problems. The key was that the problems became increasingly more complex. As the people solved the problems, the researchers analyzed their pupils. They discovered that the more difficult the task we were faced with, the more our pupils dilated.
- Your brain is oversaturated
In 1973, psychologists at the University of California wondered whether pupils could indicate when we were reaching the limits of our cognitive capacity. They recruited a group of volunteers and asked them to solve a problem that appeared on a computer screen as quickly as possible. They only had to choose one answer from four options. The trick was that the problems went by faster and faster, until a point was reached where people felt overwhelmed and could not continue. This showed that when our brain is overloaded, the pupils decrease considerably in size.
In 1977, psychologists at the University of California conducted a very interesting experiment: they recruited a group of people and asked them to listen to an erotic book, a story about mutilation and neutral content that did not arouse any particular emotion. The curious thing was that the pupils dilated at the beginning of each story, but only remained dilated during the erotic and violent stories, quickly returning to their normal state during the neutral story. Therefore, when someone really captures our interest, the pupils dilate and stay that way.
- You feel disgust
In 1960, a group of psychologists at the University of Chicago prepared a series of images that could trigger different reactions. While people were watching them, a camera recorded their pupils. It was found that when people saw violent images, mutilations or people hurting children, they reacted with deep disgust. The curious thing is that at first their pupils dilated but immediately afterwards they decreased considerably in size, in an unconscious attempt to avoid the images that aroused disgust.
- You experience pain
In 1999, psychologists at the University of Washington recruited a group of people to participate in a painful experiment for a good cause: science. They applied small electric shocks to the tips of these people’s fingers, and while doing so, they recorded their pupils. They were able to observe that when we feel pain, our pupils dilate a lot, which is a response of the autonomic nervous system that prepares us to flee from danger and, obviously, demands that our vision be 100% sharpened in order to detect any potential threat in the environment.
- Reveal your political position
In 1969, one of the most curious studies was conducted regarding what our pupils communicate. On that occasion, psychologists from Louisiana State University recruited people who had very distinct political positions and were sure of them. Thus, they presented them with photos of great personalities, traditionally liberal or conservative. At this point, the researchers noticed that our pupils dilate when we see people who share our political ideas, and contract when they belong to opposite parties.
This time it’s not about constricted or dilated pupils but about the lines of the iris. According to researchers at Karolinska Institutet, if we look closely enough at someone’s eyes, we can discover some characteristics of their personality. When the crypts found in the iris (wavy filaments) radiate outwards from the pupil, people tend to be more sensitive, honest, friendly and experience more positive emotions. When concentric folds appear around the iris, people are more nervous and impulsive. The key lies in the gene Pax6, which is not only involved in the growth of eye tissue but also in the development of the anterior cingulate cortex, which is involved in mood regulation and self-control.
Changes too small to notice?
Right now you’re probably thinking that these details are too small to notice. However, according to a study conducted at Dartmouth College , we probably don’t notice many of these changes consciously, but they don’t go unnoticed by our subconscious.
These neuroscientists analysed the brain activity of dozens of people as they looked at others, with their pupils dilated, normal or contracted. They were able to see that our brain reacts differently, especially the amygdala, which is our emotional sentinel. In fact, when another person’s pupils dilate, the amygdala increases its activity, perhaps to tell us that we should be alert.
References:
Demos, KE et. Al. (2008) Human Amygdala Sensitivity to the Pupil Size of Others. Cerebral Cortex ; 18(12): 2729-2734.
Larsson, M. et. Al. (2007) Associations between iris characteristics and personality in adulthood, Biological Psychology ; 75(2): 165–175.
Chapman, C.R. et. Al. (1999) Phasic pupil dilation response to noxious stimulation in normal volunteers: Relationship to brain evoked potentials and pain report. Psychophysiology ; 36(1): 44-52.
White, GL & Maltzman, I. (1977) Pupillary activity while listening to verbal passages. Journal of Research in Personality ; 12: 361-369.
Poock, G. (1973) Information processing vs. pupil diameter. Perceptual and Motor Skills ; 37: 1000-1002.
Barlow, JD (1969) Pupillary size as an index of preference in political candidates. Perceptual and Motor Skills ; 28: 587-590.
Hess, EH & Polt, JM (1964) Pupil Size in Relation to Mental Activity During Simple Problem-Solving. science ; 143(3611): 1190-1192.
Hess, EH & Polt, JM (1960) Pupil Size as Related to Interest Value of Visual Stimuli. science ; 132(3423): 349-350
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