In the center of our eyes, the pupils are located – holes responsible for the passage of light from the external environment to the retina. They regulate the entry of light from movements that are involuntary to us: the iris muscles decrease or increase the size of the pupil, depending on the greater or lesser amount of light in the environment.
We have no direct control over pupil dilation or contraction. But now a young man is making some researchers rack their brains: he can voluntarily shrink and enlarge his pupils.
The 23-year-old is a psychology student at the University of Ulm, Germany, and has not been named. He is identified only by the initials DW, and his case was reported recently in the magazine International Journal of Psychophysiology.
Until now, scientists know that some people can purposely change pupil size using indirect methods. For these people, just thinking about a very bright or very dark environment, for example, or making a great mental effort to concentrate would be enough to dilate or contract the pupils.
But DW’s case challenges what is known so far: it does not appear, from what the researchers have investigated, that the young man is resorting to some indirect method to control the “girl with the eye”. DW realized he could change the size of his pupils when he was about 15 years old. He claims that he feels the iris muscles directly and that, to make these movements, he only needs to focus on the eye – he doesn’t imagine a light or dark environment, for example.
“Contracting the pupil is like holding, tensing something; making it bigger is like releasing it completely, relaxing the eye,” DW told the team of scientists who investigated the case.
A series of tests were carried out, using pupillometry and optometry techniques, to verify indirect mechanisms that can mediate the phenomenon, according to write The researchers.
One of the tests, for example, consisted of measuring the electrodermal activity of the student – a property of the human body that causes continual variations in the electrical characteristics of the skin. In this test, it would be possible to see if, while controlling his pupils, DW was under intense mental effort. But that was not the case.
The researchers confirmed that the student did indeed have the ability to control pupils, and found no indication that he was using any of the known indirect methods.
From observation and investigation of this rare case, scientists believe that possibly direct voluntary control of the pupils’ muscles is possible.
Christoph Strauch, senior author of the study, he said to the portal Live Science that probably other people can learn to do this.
Now, finding and studying more individuals with this ability could help researchers understand the phenomenon and find out if there really are techniques to control pupil size at will.
“Some people got in touch [com a equipe] and believe they’re capable of doing the same thing – that’s really cool,” he said Strauch.
And you, reader, can you control your pupils?