You've probably seen this optical illusion before, and haven't thought much of it.
This image, called "My Wife or Mother-In-Law," is one of the most well-known illusions in history, and apparently, it's one that you should pay closer attention to.
It first appeared in a 1888 German postcard, and was later redrawn by a British cartoonist in 1915.
Researchers now believe that what you see in this image all depends on your age.
So the question is, what do you see?
Do you see the illustration of an older woman with a pointed chin and hooked nose looking towards the left or a young woman staring off into the distance?
The first woman that you see apparently says a lot about your age, according to a new study published in the journal Scientific Reports.
The study showed the illusion for half a second to approximately 400 participants between the ages of 18 and 68.
The participants who were able to identify that this was an image of a woman were asked to then guess the woman's age.
The people who saw a younger woman were more likely to be young themselves, while the older population were more likely to see an older woman.
How to see the two:
If you're having a hard time seeing the younger woman or older woman, the side-by-side images below will help you distinguish the two.
The image on the left shows the younger woman staring off into the distance. The older woman's eyes serve as the ear and the lips serve as the necklace.
The image on the right shows the older woman, whose lips are the younger woman's necklace and the face is the nose.
So, what does this all mean?
According to the study, we process faces that are similar to our own ages better, which tends to create a bias.
"The effect of the observer’s age on the estimated age of the woman is consistent with an own-age social group bias," the researchers explain.
"Within the respective age-groups, participants have a bias towards processing faces of a similar age."
[H/T: Live Science]