New Delhi, Sept. 6 -- Optical illusions and brain puzzles have become a favorite pastime on the internet, with thousands of people taking up the challenge to test their observation skills. The latest puzzle that is grabbing attention asks viewers to spot the hidden word "Toxic" in a grid full of the word "Taxic."

The puzzle looks close to impossible at first sight. All the boxes have the same 5-letter words, and because of repetitive letters, our eyes often get confused. But if you slow down and carefully scan row by row, you'll notice a small but important difference.

Our brain is used to spotting patterns. When the same letters keep repeating, it quickly assumes they are all the same and skips over tiny changes. That's why small diffe...