Noticing Illusions

And why to keep trying — no matter how challenging it might seem!

Last issue, we checked out an optical illusion video that illustrated graduate change blindness — “a phenomenon in which observers are unable to notice changes to the world around them when those changes occur gradually.” As I mentioned in that post, there is other academic research around the difficulty of noticing change, and I want to share some of that with you today.

Specifically, I want to talk about two related (short) videos related to the broader idea of inattentional blindness — basically, that refers to stuff we miss because our attention is elsewhere.

One of these videos has, over years of use in talks and spreading online, become rather famous; the other is less well-known¹. This makes them even harder to write about than last week’s video — but I’m going to try! Because I think there’s a useful point to be made about these videos as a pair.

The first one (the one that’s become famous) dates back to 1999, when Daniel Simons and Christopher Chabris conducted “the selective attention test.” This involved asking subjects to watch a short clip, in which six young people toss two basketballs around. Viewers are instructed to count “the number of passes made by the people in white shirts.”

The results became a staple in conference talks that related the “test” to an endless variety of subjects. If it happens that you’ve never heard of this experiment, it’s worth taking the selective attention test before you read any further. The video lasts about a minute and twenty seconds:

If you already have seen this clip — or even if you watched it for the first time just now — it’s worth taking the sequel “test,” which Simons created a decade or so later. It’s a minute-and-forty-second video. (If you’ve never seen either video, definitely watch the original before you watch this one.)

Obviously as I continue I’ll spoil the point of both experiments as I make a few observations below, so if you want to experience one or both, do so now. I recommend it.

Then I’ll share some of what the researchers have said about the results, along with my thoughts — and then, just for fun, a couple more short illusion/perception videos.