Daniel Wirtz thought he was watching a child prodigy at work. The 9-year-old girl on a German game show was solving complex spot-the-difference puzzles in seconds. "To my eye, both images looked exactly the same," Wirtz writes in his blog. "But it took her only a couple of seconds to call out that one coffee bean was missing."
A Redditor revealed her secret. She crosses her eyes to make the images merge. "For a moment, the images just seemed to blur over each other," Wirtz describes. "But then suddenly, the images seemed to lock together in the middle, creating a third image between the two others that I was able to focus on."
He includes some examples in his post to try out the technique for yourself.
Previously:
• I've watched this video of optical illusion drawings over and over and still get surprised
• Mr Angry and Mrs Calm optical illusion
• Take a seat before checking out this optical illusion
• I couldn't figure out this optical illusion painting until the very end
• Optical illusion: impossible anti-grav ramps
• Fantastic physical model of famous optical illusion melted my mind
• World's largest 3D painting creates nifty optical illusion
