Not being able to spot the difference in these characters could mean that you may get Alzheimer's in the future.
Known as Greebles, the little purple characters have been designed by scientists in their ongoing quest for a cure. A study found those at genetic risk of the disease struggle to distinguish a subtle difference in one of the images.
Experts say the test with Greebles can provide a cheap and effective way to identify individuals in the early stages of the disease.
Try it for yourself below: