Just watch this video first, then read the words. Seriously. Follow the instructions and count how many times a player wearing white passes the ball:

Daniel Simons and Christopher Chabris study how the human mind works. In a series of test videos, they ask participants to perform a task, then at the end you'll learn how you stacked up.

First is their most famous video, involving basketball passing. As the video explains, you'll need to watch the players wearing white and count how many times they pass the ball (and note that there are two balls in play!). It takes a surprising amount of concentration. Concentrate and count. It only takes a minute:

How did you do?

Perhaps more importantly, would you like to try out more videos like this? Good, because Simons and Chabris have tons of them. One of my favorites is the movie perception test. Give it a shot:

If you're into this stuff, check out the authors' website, and their book about what these tests reveal.