New Delhi, Aug. 18 -- Optical illusions are all the rage currently. The latest puzzle making the rounds on the internet will put your eyes and focus to the test. You need to find the word HAND hidden in a grid full of HNADs. To solve the puzzle, players have only eight seconds to find the odd word out.

At first glance, every set of letters looks the same. H, N, A, D. But one word stands out - the only one spelled correctly. The challenge is simple on paper, but once you are staring at rows of jumbled letters, the pressure starts building.

Letter-grid illusions work by tricking the brain's pattern recognition system. Our eyes scan the letters, but the brain is so used to grouping familiar patterns that it sometimes overlooks small differ...