This Coca-Cola optical illusion continues to boggle minds

There are some optical illusions that continue to baffle us long after they first went viral online. One of those, and perhaps one of the best optical illusions we saw this year. is the Coca-Cola can illusion. 

We all know that a Coca-Cola can is red. Except when it's either Coke Zero or an optical illusion. Despite how it appears. That Coca-Cola can you see above is not red. I promise. (see our history of the Coca-Cola logo to learn about the development of the brand).

It's not the first time that we've seen the Coca-Cola can optical illusion. But it's resurfaced on X (Twitter to most of us), and it's boggling minds all over again. Shared by Akiyoshi Kitaoka, an experimental psychologist who studies visual illusions, the image shows a Coke can against horizontal stripes. The can appears to be red, as we'd expect because, well, it's a Coke can. But if you zoom in to focus on only a portion of the image (or just drag it into Photoshop and use the colour picker, you'll find that it's actually grey.

What happens, it seems, is that our brains get confused by what our eyes see because of how the cone and rod receptors in our eyes respond to colour and light. Surrounding grey with blue makes your brain susceptible to interpreting it as red. And knowing that a Coca-Cola can is usually red may exaggerate the effect. Intriguingly, the optical illusion also appears to trick ChatGPT.

Kitaoka has shown that a similar illusion occurs when the image is made with yellow lines. In this case, the can appears to look blue (but isn't).

The illusion works in a similar way to the woman with blue eyes optical illusion. A cyan filter only lets cyan-coloured light through, so anything else should look grey. For more mind-benders, see our pick of the best optical illusions.