The Jastrow Illusion Moment We Can All Relate

Henry Cheng
2 min readFeb 4, 2018

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Take a look at the picture below, which one is longer?

First Picture

Yes. B appears to be longer.

Now, which one looks longer in the following picture?

Second Picture

This time, the upper one, A, looks longer.

In fact, they are the same (stop rubbing your eyes.)

This is known as the Jastrow illusion, discovered by psychologist Joseph Jastrow, who found that when two identical figures are placed next to each other, they appear to be different in size. The cause is still unknown, but the most common explanation is because our brain is confused by the difference in length between the small and the large radius.

Our brain compares the longer radius of B to the shorter radius of A. Thus, B appears to be longer (Sorry for the terrible trace)

So, you may wonder what about Jastrow illusion that has anything to do with your life?

Background story:
I was busy cooking and laying out two same size plates, with the exact same position as the first picture, to fit my stir-fried veggies and teriyaki chicken, and I saw the illusion. Boom!

This is not about how I learned how to cook, but it’s about the similarities to the “grass-is-greener-on-the-other-side” mindset.

Imagine if you were “A” in the first picture, you would think B is larger and longer. However, If you were “A” in the second picture, voila, seems like you’ve won the race.

Fact is, there’s no race.

You think the person has a better life and career from your perspective, but the person actually thinks you are the one in the front. If you are comparing your weaknesses to others’ strengths, of course you feel defeated. But if you compare strengths with each other (I doubt if it’s comparable since we all have unique backgrounds and strengths), you all might just be on the same page.

Where you are doesn’t define who you are.

Ask yourself if you’re making the wrong comparison, or is there even a meaning in comparison. Sometimes we just need to pull ourselves away and examine the Jastrow illusion from afar.

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Henry Cheng

I love studying techniques that make people say YES! Sometimes I write about careers and sometimes I write in Chinese. English as a second language :)