Riddles that challenge us to spot differences between 2 similar images activate our concentration power to the maximum: they put our eyes and brain to work. This is great because training our minds is as important as exercising our muscles. Which tank will get full first?

Sometimes we look at an image and something immediately catches our attention because it is not where it should be. Other times we feel that something is wrong, but we don’t understand exactly what it is and so we have to look more closely.