Optical illusion, Sept. 14 -- Word-based illusions can be just as tricky as picture ones. This latest challenge to grab attention has a grid made up of 12 columns and seven rows. Every single cell carries the word Illosion. The trick is that one cell hides the real spelling - Illusion. Only those with sharp eyes will notice the odd word before the grid starts blurring together.

Many people scroll past quickly, assuming it is all the same. But spend a few extra seconds and you will see the slip. The brain tends to gloss over tiny spelling shifts when the same shape keeps repeating. That is what makes this test frustrating and addictive at the same time.

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