Given I knew what the test was before seeing one of these videos (yes, there is more than one), I find it extra weird that I still didn't see the gorilla the first time.
A spoiler for a fifteen year old news story that describes this in the middle of the article, explaining what was already at the time a ten year old video, where my anecdote demonstrates that even prior warning isn't sufficient to see it?
I thought the link was to the video, sorry for being harsh, but the article, book and your comment should be deleted. The video is too great and spoilers make it less great.
Now, I see it every time.