Optical illusions have long fascinated humans, with our brains constructing a simulation of reality rather than directly accessing it, according to neuroscientists Stephen Macknik and Susana Martinez-Conde. The Best Illusion of the Year contest offers researchers and participants an opportunity to explore the gaps and limits of human perception.
Studying optical illusions helps scientists understand which brain regions and processes help us interpret the world around us. One example is change blindness, where our brains fail to notice shifts in the environment, especially when they occur gradually. The illusion above highlights this phenomenon, with dozens of objects changing in a video that won second place in the contest.
The contest, now in its 18th year, reflects how much of the human brain is devoted to making sense of what we see. Dr. Macknik and Dr. Martinez-Conde run the contest annually, which initially began as a public outreach event at an academic conference. The researchers have found that people create new illusions with the intention of competing in the contest.
Illusions appear in everyday life, such as when stationary rocks on opposite banks appear to move upstream after gazing at a flowing stream for some time. This phenomenon is known as the “waterfall illusion” or motion aftereffect. Other illusions are created intentionally, like the blue rows that slant in this image, which demonstrates how certain shapes can distort appearances while electrical signals in the brain interfere with each other.
The brain’s ability to anticipate and predict illusions reveals its complex processing mechanisms. For example, Dr. Macknik accurately predicted that a center bar would disappear if outer bars came too close together. This effect is more pronounced when viewing the bars with peripheral vision, highlighting the importance of distance in perception rather than real space.
Dr. Martinez-Conde notes that our brains can generate illusions through any sense, but most submitted to the contest are related to visual perception. She attributes this to the online nature of the contest, which showcases how much processing power is devoted to making sense of what we see.
The researchers describe perception as a bag of tricks used by the brain to navigate the world efficiently. However, this approach has limits, and illusions reveal the cracks in the “plaster” of reality that our brains construct for us. The study of optical illusions offers insights into the workings of the human brain, providing a deeper understanding of its complex mechanisms.
Source: https://www.nytimes.com/2025/06/26/science/neuroscience-brain-illusions.html