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Famous ‘moon footstep’ optical illusion shows the trick our brain plays

As Tom Stafford over at the always-interesting Mind Hacks blog demonstrates this week, our brains often play visual tricks on us.  Here’s the famous photo of Buzz Aldrin’s footstep on the moon.

As Tom Stafford over at the always-interesting Mind Hacks blog demonstrates this week, our brains often play visual tricks on us. 

Here’s the famous photo of Buzz Aldrin’s footstep on the moon. Notice something strange — how the footstep appears to be rising out of the moon’s surface rather than being impressed into it?

Buzz Aldrin lunar footprint
Courtesy of NASA

“The effect,” explains Stafford, “is due to a well known visual phenomenon whereby our brains use shading to infer the perception of shape. We are wired to assume that light comes from above, so things with shading underneath, like the ridges of the footprint, are seen as sticking out towards us. Things with shading on the top are seen as sticking in, away from us.”

As Stafford notes, the optical illusion disappears when you turn the photo upside down because from this angle the photo “gels with our natural inclination to assume light comes from the top of the photo.”

Buzz Aldrin lunar footprint
Courtesy of NASA

Use this a reminder as you go into your weekend: Don’t believe everything you see — or, for that matter, read!