Every year the Neural Correlate Society makes a list the best illusions of the year. These aren't the tricks that got Gob thrown out of The Alliance of Magicians. They're optical illusions that push the brain's ability to process "perceptual experiences that do not match the physical reality."
The organization looks at optical illusions as a form of discovery. "How we see the outside world―our perception―is generated indirectly by brain mechanisms," the organization writes, "and so all perception is illusory to some extent. The study of illusions is critical to how we understand sensory perception, and many ophthalmic and neurological diseases."
The puzzling illusions they select make that whole blue dress/gold dress thing look pretty tame. Below are the top four illusions of 2016, as judged by the Neural Correlate Society.