Mystery Surrounds Optical Illusion Perception: Only 80% of Individuals Can Decipher It, Remaining Reason Unclear
In a groundbreaking study published in the journal Frontiers in Human Neuroscience, researchers from the University of Oslo in Norway have delved into the intriguing world of optical illusions. Specifically, they focused on the "expanding hole" illusion, a visual phenomenon that has left many puzzled.
The study involved 50 participants with normal vision who were asked to rate the strength of the illusion they perceived. The illusion is presented on a white background with a black dot at the center, which appears as a hazy black hole. Gazing deeply at the black splodge may cause the shape to appear as if it's expanding.
Not all participants were able to perceive the illusory expansion. 14% didn't perceive any illusory expansion when the hole was black, and 20% weren't sure if the hole was in color. However, about 80% of people experienced the full effect of the illusion, but the reason for this remains a mystery.
The researchers found that the illusion can deceive the brain's automatic visual reflexes. Pupil dilation and constriction are not solely guided by real changes in the physical environment. They also respond to our own perceived and imagined light conditions.
When the "hole" is colored instead of black, the pupils constrict, as if adapting to brighter light. Conversely, when the hole is black, some people's pupils dilate, mimicking a response to moving into a dark area. The intensity of the illusion was correlated with the change in pupil diameter: stronger individuals rated the illusion more intensely, and their pupil diameter tended to change more.
Dr Bruno Laeng, a professor at the Department of Psychology of the University of Oslo, described the illusion as "highly dynamic" and evoking an impression of optic flow. He concluded that the "pupils' dilation or contraction reflex is not a closed-loop mechanism."
The study also measured the eye movements and unconscious constrictions and dilations of the participants' pupils during the experiment. The researchers hope that their findings will shed light on how our brains process visual information and how optical illusions can influence our perceptions.
Despite the advances made in understanding this fascinating illusion, the specific name of the research group studying optical illusions strong enough to deceive automatic visual reflexes in the brain remains unclear. Nonetheless, the study provides a compelling insight into the complex interplay between our eyes, brains, and the illusions we perceive.
