How This Year's Best Optical Illusions Trick Your Brain

Have you ever looked at something and been sure of what you saw — only to find out your brain was wrong? Every year, the Best Illusion of the Year Contest shows off the most mind-bending visual tricks from around the world. This year's winners were announced Tuesday by the Museum of Illusions, which is based in Zagreb, Croatia, and has more than 70 locations worldwide. Scientists, artists, and everyday people all voted to pick the top illusions from dozens of entries.

The first-place winner is called 'Cogs in a Machine,' created by Jacky Z.J. Yueh and Joan Danielle K. Ongchoco of Canada. The illusion uses two identical gears, each with eight teeth, spinning at the exact same speed with their teeth touching. When you look directly at one gear, the other gear — seen out of the corner of your eye — appears to spin faster, even though both are moving at the same speed. This happens because of how your peripheral vision, or side vision, processes motion differently than your central vision.

Neuroscientist Susana Martinez-Conde, from SUNY Downstate Health Sciences University in Brooklyn, explained that the brain uses different types of nerve cells, called neurons, for different jobs. The neurons in your peripheral vision are especially good at picking up movement. Meanwhile, the neurons in your central vision are better at detecting shapes and fine details. This division of labor is what makes the gear illusion possible.

The illusion gets even stronger when the teeth of the two gears are offset, meaning they weave between each other instead of touching directly. Instead of the brain processing eight pairs of teeth per rotation, it now has to handle 16 separate events. Martinez-Conde believes this higher number of quick changes tricks the brain into thinking the motion is even faster. Our brains respond especially strongly to sudden changes, which is why this version of the illusion feels so powerful.

This isn't just a fun trick — it connects to real life. Martinez-Conde noted that when you walk or drive, how fast something seems to move depends on whether you're looking right at it or catching it out of the corner of your eye. That difference in perception can really matter when you need to stay safe on the road. Understanding this helps scientists learn more about how the brain interprets the world around us.

The second-place illusion is called '9 Purple Dots,' created by Hinnerk Schulz-Hildebrandt, a doctor who teaches at Harvard Medical School. He got the idea while looking at a flight-tracking website, where a purple line seemed to change color as he moved his eyes. In his illusion, nine purple dots sit on a bluish background. Whichever dot you look at directly appears purple, but all the others seem to shift toward blue.

This color-switching effect comes down to how your eyes are built. Inside the eye is a part called the retina, which has special cells called cones that detect color. There are three types of cones — ones sensitive to red, green, and blue light — but the very center of your retina has very few blue-sensitive cones. So the dot you look at directly actually appears less blue than the ones around it, making it look more purple by comparison.

Martinez-Conde used this illusion to share a surprising idea about color. 'We often think of colors as objective properties of the world, and this is not true,' she explained. 'The world does not have color. Color is always a brain construct.' In other words, your brain creates the colors you see — they don't exist on their own 'out there' in the world.

The third-place winner, 'The Hole Truth,' was made by Matt Pritchard from Britain. It features a 3D sign with letters that have holes cut out of them, and when viewed in a mirror, the sign spells a completely different — and opposite — word. This type of object is called a 3D ambigram, because it looks different depending on your angle of view. The brain is tricked into grouping parts of the cutout letters with the dark background, creating a false impression of what the shapes spell.

Martinez-Conde said illusions like this one remind us that our brains don't always get things right, even when we feel completely certain. 'It can be very hard or even impossible to overcome our neural wiring,' she said. She hopes that exploring illusions encourages people to pause and question their own assumptions. Asking yourself 'Am I absolutely sure this is the complete truth?' is a habit that scientists — and everyone — can benefit from.