We can tell how smutty your brain is based on what you see first in this two-in-one image.
The answer is probably very smutty.
The more innocent among you will have seen nine dolphins.
Those who are sex obsessed will have seen two people sharing an 'adult cuddle'.
Orginally by artist Sandro del Prete, published on his site Impossible World, the work is entitled 'Message d’Amour des Dauphins'.
The reason the brain is able to see two images almost simultaneously is because it's received equally plausible visual information.
You see one image before the other based on memory, like your brain using a short code to turn visual information from the eye into a picture that you recognise.
As such, the younger, who have probably seen fewer naked women than grown ups, bring up dolphins, whereas adults often see the naked couple first.
Cognitive psycologists study optical/visual illusions because they help to understand how the brain processes images of non-illusions.
Which did you see first?