Man from Germany can change his pupil size on command


In a rare case, a 23-year-old can “tremble” with his eyeballs

According to an extremely unique case report, a 23-year-old student from Germany has the ability to shrink and enlarge his pupils on command. This is something that till this case study was thought to be completely impossible. However, some studies have shown that some people can change their pupil size by using indirect methods. Researchers are already familiar with the fact that thinking about the sun can constrict the pupils. Whereas thinking about a dark room or calculating something mentally can dilate them. This was outlined in a study by Christoph Strauch. For example, researchers already knew that just thinking about the sun could constrict the pupils and that thinking of a dark room or mentally calculating something could dilate them, said Christoph Strauch, senior author of the case report and an assistant professor in the experimental psychology department at Utrecht University in the Netherlands. 

In this scenario the two opposing muscles in the eye act as puppeteers for the pupils, dilate and enlarge them in the dark environment to allow more light. In addition, constrict them in a bright environment, limiting the amount of light flowing in. This process is otherwise, completely automatic. For example, you do not have to tell your pupils to change size when you are in a dark room or in response to increases in arousal. But changing the size of the pupil by controlling it like a muscle was never thought to be possible. Until this student of psychology at Ulm University in Germany was able to.

When he was about 15 or 16 years old, he realised he could change the size of his pupil

“I showed a friend that I can ‘tremble’ with my eyeballs, and he noticed that my pupils became small,” D.W. told Strauch and his colleagues at Ulm University. However, he was unaware of this ability of his till he played computer games for long time periods.

“Constricting the pupil feels like gripping, tensing something; making it larger feels like fully releasing, relaxing the eye,” D.W. told the researchers. At first, he would change his pupil size by focusing in front of or behind an object, but with practice, he learned how to do it without focusing on objects. He told the researchers that, to change his pupil size, all he has to do is concentrate on the eye; he doesn’t have to imagine a bright or dark environment. 

He has the ability to dilate his pupils 0.09 inches (2.4 millimeters) in diameter and constrict them to 0.03 inches (0.88 mm) in diameter.

Currently there aren’t any studies to explain this phenomenon. Although, according to Strauch, “Quite some people have reached out who believe that they might be able to do the same thing — this is really cool.”

Source: International Journal of Psychophysiology

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Dr. Aiman Shahab is a dentist with a bachelor’s degree from Dow University of Health Sciences. She is an experienced freelance writer with a demonstrated history of working in the health industry. Skilled in general dentistry, she is currently working as an associate dentist at a private dental clinic in Karachi, freelance content writer and as a part time science instructor with Little Medical School. She has also been an ambassador for PDC in the past from the year 2016 – 2018, and her responsibilities included acting as a representative and volunteer for PDC with an intention to make the dental community of Pakistan more connected and to work for benefiting the underprivileged. When she’s not working, you’ll either find her reading or aimlessly walking around for the sake of exploring. Her future plans include getting a master’s degree in maxillofacial and oral surgery, settled in a metropolitan city of North America.


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