Optical Illusion: You have eagle eyes if you can spot O among Qs in 4 seconds! In this optical illusion picture, the letter O is hidden among Qs. Only eagle-eyed individuals can spot O among Qs in 4 seconds. Can you? Attempt now. Optical Illusion: Illusion is derived from the Latin word illudere, which means to mock or trick. Therefore, the basic premise of an optical illusion is to deceive the human brain by tricking it. Optical illusions enhance cognitive abilities and stimulate the brain to think creatively. They are a fun way to challenge your mind and improve your problem-solving skills. Studies have shown that engaging in such brain-challenging activities regularly can help reduce the risk of cognitive decline in adults and improve overall brain function.