First "The Dress," then "Guess the Mommy" and now this — nothing quite capture's the country's attention like a photo that makes you stop and look twice (or three, four, five times). The latest viral sensation is this snap taken by Swiss photographer Tiziana Vergari. The optical illusion makes it nearly impossible to tell how many girls are actually in the photo. 
Two? Four? Fifteen? Take another close look below and try to figure it out:

Stumped? You're not alone. The photo has been shared more than 12,800 times since Vergari posted it one week ago, with debates raging in the comments about what we see. Ready for the answer?
Wait for it...

According to Vergari, there are only two girls in the photo. In all likelihood, they're her daughters.

 (Photo: Tiziana Vergari via Instagram)