How do you see "1" in depth? 1. Left: convex, right: convex 2. Left: convex, right: concave 3. Left: concave, right: convex 4. Left: concave, right: concave (Japanese 1 yen coin)pic.twitter.com/l7s2SXt9Yo
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But rotate 90, 180, or 270 degrees, and see (perhaps) different results.
It's coz of shadow line?
Sorry I misvoted. I blame my phone. Remove me from 1 add me to 2.
I understand:D
Depends on what part of the coin you look at.
Whats a convex? (just kidding) 
I'd be curious to see how many people who voted 2 were right-handed and 3 were left-handed?
I was going to vote one way, then I rotated my head and it was different. I can manage to get them to flip convexity / concavity if I rotate my head and blink.
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