Concerned about your risk of Alzheimer's? A simple test asking to pick the odd image from a set of four is thought to help identify those at risk of developing the illness.
Known as 'Greebles' these little figures are used to test facial recognition. If someone has trouble identifying which of the images doesn't belong in the set, it could indicate early stages of Alzheimer's disease.
Dr Brandon Ally, of the University of Louisville is eager to stress that this is by no means a way of definitively diagnosing any condition, but it could have its uses:
'We are not proposing that the identification of novel objects such as Greebles is a definitive marker of the disease.
'But when paired with some of the novel biomarkers and a solid clinical history, it may improve our diagnostic acumen in early high-risk individuals.
'As prevention methods, vaccines or disease modifying drugs become available, markers like novel object detection may help to identify the high priority candidates.'
So which of the images below doesn't belong?
Researchers hope that tools like this will help diagnose people in the earliest stages of the disease, which will make huge differences in quality of life.
The lead author of the study, Dr Emily Mason, said:
'Right now, by the time we can detect the disease, it would be very difficult to restore function because so much damage has been done to the brain.
'We want to be able to look at really early, really subtle changes that are going on in the brain.'
So which one is it?
No. 4 is the different Greeble.
The difference is subtle, but one of its two 'arms' is flatter than the other characters. And the spikes on the 'head' are more pointy.
As always, if you have any concerns about your health and the topics raised in this article, ask your doctor.