Optical Illusions Convince the Brain They're Moving

According to a growing number of international brain experts, optical illusions do not only fool the eyes as to their contents, but also the human brain, which tends to perceive everything it sees literally. For example, when looking at an illusionary trick meant to inspire movement, some people actually get motion sick, although they obviously know that nothing is moving in the image, and that everything is just a figment of their imagination.

The Association for Research in Vision and Ophthalmology has recently announced that Japanese researchers at the Ritsumeikan University in Kyoto, led by Akiyoshi Kitaoka, surveyed brain activity levels of test participants, using fMRI, a new technique that allows real-time observations of the changes that occur in the parts of the brain that usually process information. Before the study, the widespread belief was that illusions were generated by higher levels of brain activity, namely by imagination.

However, the recent study, published in the Journal of Vision, as part of a neuroimaging series, shows that when people view illusions, it's not imagination that makes them perceive movement, but rather a part of the brain from the visual cortex, which is regularly involved in detecting and interpreting real physical motion and movement. "The illusory motion percept is not just the observer's imagination," Tohoku University associate professor Ichiro Kuriki, PhD, who has also been a member of the research team, says.

For the study, the team used the Rotating Snakes illusion, which was made up of many circles, carefully drawn in such a manner that they appeared to be in constant motion when compared to each other. The drawing is very vivid, and the researchers noticed that, whenever people would move their eyes from one circle to another, their visual cortex, and especially the physical movement detection region, would "light up," denoting higher levels of activity.

Understanding how these illusions act on the human mind, and especially what shapes are prone to creating confusion may help designers of all trades create better products that do not confuse people through their highly-elaborate design. This is especially important in cars or surgical equipments, for example, as human lives are at stake.