What Color Is That Fire Truck? The Mind-Bending Illusion Tricking Your Brain
Mind-Bending Optical Illusion Makes a Grey Fire Truck Look Red
From the infamous “blue vs. gold dress” to hidden objects in brick walls, optical illusions continue to fascinate. Now, a new puzzle from biologist and BBC presenter Dr. Dean Jackson has stunned viewers: a fire truck that appears red—even though it’s actually grey.
[Image 1: Red fire truck on a road (Caption: The original image shows a bright red fire truck.)]
In a TikTok video, Dr. Jackson starts with a red fire truck image before applying a cyan filter. “What color is the truck now?” he asks. Despite the filter, the vehicle still seems red. But the trick? The cyan filter blocks red light entirely, leaving the truck devoid of red hues.
[Image 2: Fire truck under cyan filter (Caption: The cyan filter removes red wavelengths, turning the truck grey—but viewers still perceive red.)]
Why Does This Happen?
Our eyes use rods (detecting motion) and cones (detecting color) to process light. The cyan filter only allows cyan light through, so the truck should appear grey. However, our brains override reality. “Your brain overcompensates because it knows fire trucks are red,” explains Dr. Jackson. It fills in the missing red, creating the illusion.
To prove no red exists post-filter, he overlays a grey square onto the truck. The colors match perfectly, yet viewers insist the square “turns red” when placed on the vehicle.
[Image 3: Grey square comparison (Caption: Dr. Jackson proves the truck and square are the same grey shade, but context fools the brain.)]
Viewers React
The TikTok sparked disbelief. Comments ranged from “The square changed color!” to debates about flickering hues. Dr. Jackson clarified: “The square doesn’t change—your brain does.”
The Science of Illusions
This trick hinges on color constancy—the brain’s ability to perceive consistent colors under varying lighting. Even when red light is absent, prior knowledge (fire trucks = red) alters perception.
Such illusions reveal how vision isn’t just about the eyes. “Brains are remarkable organs,” says Dr. Jackson, highlighting how they interpret ambiguous signals using context. Next time you see a puzzling image, remember: reality might just be in your head.
[Image 4: Side-by-side of Café Wall Illusion (Caption: Other illusions, like the Café Wall, use contrasting tiles to warp perception.)]
Credit: Dr. Dean Jackson/TikTok
Final Word
Whether it’s a dress or a fire truck, optical illusions remind us that seeing isn’t always believing—sometimes, it’s your brain filling in the blanks.
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