What we don’t notice…

by Chris Bertram on May 6, 2004

There’s “a nice little piece in today’s Telegraph”:http://www.telegraph.co.uk/connected/main.jhtml?xml=/connected/2004/05/05/ecfgorilla05.xml&pos=portal_puff1&_requestid=347199 about the psychology of visual perception and how we fail to notice all kinds of things because our attention is directed in particular ways (of course conjurors have always exploited this). The article refers to the striking gorilla-suit experiment:

bq. Working with Christopher Chabris at Harvard University, Simons came up with another demonstration that has now become a classic, based on a videotape of a handful of people playing basketball. They played the tape to subjects and asked them to count the passes made by one of the teams.

bq. Around half failed to spot a woman dressed in a gorilla suit who walked slowly across the scene for nine seconds, even though this hairy interloper had passed between the players and stopped to face the camera and thump her chest.

bq. However, if people were simply asked to view the tape, they noticed the gorilla easily. The effect is so striking that some of them refused to accept they were looking at the same tape and thought that it was a different version of the video, one edited to include the ape.

There’s also a link to a “page where you can watch the gorilla video”:http://viscog.beckman.uiuc.edu/media/dailytelegraph.html . (For that video on its own go “here”:http://viscog.beckman.uiuc.edu/grafs/demos/15.html .)



Motoko Kusanagi 05.06.04 at 9:19 am

That reminds me of this (slightly silly) article on luck. (“I gave both lucky and unlucky people a newspaper, and asked them to look through it and tell me how many photographs were inside. I had secretly placed a large message halfway through the newspaper saying: “Tell the experimenter you have seen this and win £250.” This message took up half of the page and was written in type that was more than two inches high. It was staring everyone straight in the face, but the unlucky people tended to miss it and the lucky people tended to spot it.”) So my question is: are gorilla suit-spotters luckier in life than others?


Chris Lightfoot 05.06.04 at 9:51 am

For those whose browsers don’t find the video on the above page (there’s some talentless bit of Javascript there), the URL
works for me.


John Quiggin 05.06.04 at 11:57 am

I tried it out on my son (age 14) and he noticed as soon as the gorilla faced the camera. Just one data point, of course.


LTH 05.06.04 at 12:27 pm

I noticed the gorilla immediately when I was shown this some time ago.


Chris Bertram 05.06.04 at 1:28 pm

I’m not surprised that people find that one easy to spot: I can’t believe that having a little QuickTime window is the optimal way of showing the movie. When I saw the experiment on British tv, though, with a camera trained on an audience watching a similar film on a big screen, the effect was very marked – with only 3 or 4 people (out of 50 odd) noticing the gorilla.


Nat Whilk 05.06.04 at 2:26 pm

Possible explanation: It’s not unusual to see a gorilla at a basketball game (see, e.g., this), but it is unusual to see people playing basketball so poorly. (Have they never heard of double dribble? Traveling?)


DJW 05.06.04 at 3:32 pm

Why the hell would a team called the Suns have a Gorilla as a mascot?

My British friends tell me about a museum of perception in London that has the following exhibit. It’s a seemingly interactive slice of urban life, where through a series of video screens you experience a series of ostensibly typical moments walking around London. At one point, an angry, rude man berates you for a 20-30 seconds for bumping into him or some such thing. Later, you witness a hit and run, and you get a good several second look at the face of the guilty party. However, in a mock line-up after the fact, most people misidentify the rude man as the hit and runner, even though they don’t look similar at all.

Or at least that’s how i remember it being told, if someone knows more about the museum/exhibit, and I’ve got something wrong about this, I’d be curious to see it.


Nat Whilk 05.06.04 at 3:49 pm

Why the hell would a team called the Suns have a Gorilla as a mascot?

The guy who had to wear the flaming-ball-of-gases suit kept complaining about the heat.

BTW, here’s a demonstration of the power of concentration that I found impressive, but YMMV.


jdsm 05.06.04 at 8:17 pm


I’m not sure what YMMV stands for but I assume it has something to do with the fact that none of the cards you are originally shown come up the second time. I worked it out almost immediately.


Nat Whilk 05.06.04 at 8:48 pm

I’m not sure what YMMV stands for

Your mileage may vary.

“but I assume it has something to do with the fact that none of the cards you are originally shown come up the second time.”

Oh, great. Ever hear of the word “spoiler”?


Hal 05.06.04 at 9:39 pm

You might want to check out Inevitable Illusions by Massimo Piattelli-Palmarini, which describes similiar things in our reasoning process.


bza 05.06.04 at 10:07 pm

It’s crucial to the experiment that viewers not only be ignorant of the gorilla but that they be primed to attend to another part of the scene. I suspect that John Quiggin didn’t prime his son forcefully enough. (When I’ve seen the experiment demonstrated, the priming has been along the lines of “It’s crucial that you count the number of passes; nothing else about the scene matters. Remember: count the passes.”)


Jonathan Dursi 05.07.04 at 2:16 am

I spent all day today looking for things like this (or, more generally, the lack of reliablity of eyewitnesses) for a class I’m teaching tomorrow. After finding nothing much worth using, I finally gave up and caught up on my blog-reading, and ta-dah!

Moral of the story: do less research, do more blog reading.

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