Eye-tracking and selective perception

In 1999, an experiment was conducted at the Harvard School of Psychology, which was then included in all textbooks. The students were shown a video in which two teams in black and white T-shirts were throwing a basketball to each other. The task was simple: count how many times the team threw the ball in white T-shirts.

If you have not heard anything about this experiment, then stop reading for a moment and watch the following video. Try the above task.
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The trick was that in the middle of the video a man in a gorilla suit passed through the entire screen, made faces ... but a very large number of respondents simply did not notice him! And they were very surprised when they were asked whether they had noticed something unusual ...
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We decided to repeat this experiment using an itracker, and see how the respondents' eyes are moving. We immediately say that out of 10 tested respondents, only two of them noticed the gorilla from the first time.

Here is what the video viewer looks like:



But what happens when, after questioning, “have you noticed something unusual?” The video is shown a second time:



Interestingly, an effect similar to this “invisible gorilla” is often observed in real life. The militia, for example, knows well that it is necessary to treat eyewitness accounts very carefully. Methods of checking the operator's attention are embedded in various tracking systems (for example, scanners at the airport), and several operators are used in sensitive areas.

Yes, and each of you, for sure, may recall cases when you stubbornly searched the page with a description of the program “Download” link and after some time, I was surprised to find it “in the most visible place” ... It is interesting to observe such cases during usability testing . Our favorite example is the “online demo” button on the UMI CMS website: a little less than half of the respondents who are looking for this demo site do not notice it, despite the fact that the button itself is done completely according to the textbook - and in the right place is highlighted in color ...