Different sized train track optical illusion explained by Jastrow illusion (VIDEO).

This “Train Track” Optical Illusion Drove People Crazy. Here’s How It Works.

This “Train Track” Optical Illusion Drove People Crazy. Here’s How It Works.

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April 11 2016 6:40 PM

Are These Two Objects the Same Size or What?

A handy example of the Jastrow illusion.

tricks

Screenshot via Slate

On Twitter, BBC Academy trainer Marc Blank-Settle attracted more than 3,000 retweets for pointing out something strange about the pieces to a wooden train set: Apart, one track appeared larger than the other, but placed atop each other, it was clear they were actually the same size. Settle summed it up for thousands of others: “What is going on here?!”

In the video above, Slate demonstrates what’s known as the Jastrow illusion, a tricky brain teaser that may arise from how two objects’ angles are compared. (No, it isn’t the camera angle.) The objects are in fact the same size, it’s just hard for our brains to see them that way.  

Aymann Ismail is a Slate video producer/editor.

Jeffrey Bloomer is Slate's senior video producer.