New Delhi, Oct. 12 -- A new holiday-themed optical illusion is driving people a little cross-eyed. The image, first shared on Reddit, shows a herd of cartoon reindeer packed tightly together - each one nearly identical, except for one small detail. Somewhere in the mix is Rudolph, the red-nosed reindeer himself. Your job? Find him before your patience runs out.

At first glance, it looks easy. A sea of brown faces, white muzzles, and antlers fills the frame, and you'd think a bright red nose would pop right out. Not so fast. The artist who created this clever puzzle clearly knew how to mess with human perception. The repetitive patterns trick your brain into skipping over details, making Rudolph's shiny nose much harder to catch than you ...