This is NPR's life kit, I'm Elise Hugh.

Most of us have probably never taken a class that's just about thinking, or more specifically

thinking traps.

But U-Kyoung-An teaches on these, and her role as a psychology professor at Yale.

Her class focuses on the common cognitive biases we fall into, sometimes without realizing

them.

She likes to start out one of her lectures by showing them a BTS dance clip.

Alright, what I'm going to do is I will play the original version first, okay?

And then we'll get to the slow down version, okay?

See whether you can do it.

So her students watch this short clip over and over again, trying to remember all the

basic steps.

The one that I use is supposed to be the easiest one, and I only got the six seconds of that

video.

And I played that like 10 times to the student, and I warned them that they can come out

and show the dance for the whole class, and they will be a prize for it.

You feel like you can do it.

Even I feel like I could not dancer at all.

But after that, they come out and don't look at the screen anymore.

I only play the music, they face the audience, and then of course none of them could do it.

The experiment with her students illustrates the fluency effect.

One of the many cognitive traps U-Kyung-An warns us about.

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