The picture above is one of my favorite optical illusions because it looks so simple. I don’t remember where I first encountered it, but the question it poses is not complicated: which of the two figures representing roads above are identical?

We’ll give you a bit of space here to consider before we continue

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Most people say that the two figures on the left are identical, and the figure on the right is the odd one. But that is incorrect. The two end figures are alike and the middle picture is different. It’s difficult to believe, but I did a little experiment with Photoshop that will help to convince you.

Using Photoshop, I cut the figure on the right, leaving only its outline behind, and moved the figure over to the left, overlapping the leftmost figure. Here’s what it looks like:

You can see that the two figures are identical, and surprisingly even the road division lines line up, something not so apparent in the top picture.

Now let’s try the same thing, only this time we’ll cut the leftmost figure, and let it overlap the middle figure:

You can immediately see that the middle figure does not match the leftmost figure as it appeared to do so in the top picture.

Now that you know what’s going on, go back to the top picture. Does it change your perception? Not mine. It’s one of the most disheartening things to me about optical illusions—even though we know exactly what is going on,  our perceptual apparatus is still fooled.

Magicians like to summarize this kind of realization by the simple statement: “Misdirection works.”

Apply to advertising and propaganda at your leisure. It works even when you know what they are doing.