Friday, March 13, 2015

Inattentional Blindness

This car ad (visible here on YouTube) is less about the car than it is about visual perception. The ad shows four buildings on a street in West London. Over the course of a minute, the screen momentarily blinks to black 13 times. After each blink, elements of the scene change.

Here's what the scene looks like at the beginning of the ad....

....and here's what it looks like at the end. 

Every single window, awning, and roofline has transformed, and even the building colors alter from the start to the finish. There's even a chimp on the roof in the upper left. About the only things that remain the same are the blue car and the bit of foliage in the upper right.

How do they get away with so many major alterations without most people noticing? They use the magician's art of misdirection as the announcer talks about the car. Then, when the voiceover suggests we look for changes, we naturally look for things that we expect to change, such as parked cars. But we aren't expecting the windows to switch. 

Even when we watch it the second time knowing what's going to happen, the differences are difficult to notice, because those short black-frame transitions are just long enough to interfere with the persistence of vision. It's hard to remember how things looked just a second ago when we don't know what we're supposed to focus on. 

This phenomenon, called "inattentional blindness," or "perceptual blindness" was made famous by a video showing people in white and black shirts passing a basketball. As the viewer is distracted by the task of counting how many times the white-shirted players pass the ball, a person in a gorilla suit walks through the scene unnoticed by more than 50 percent of the viewers. 

The problem of inattentional blindness affects the performance of police officers looking for one suspected crime and missing another crime happening in plain sight. It also affects the awareness of drivers distracted by their cellphones. 

What we see—and what we don't see—has a lot to do with what our minds are focused on, and what we're looking for. 


M.A. said...

These are wonderful!

Tobias Allen Wolf said...

Interesting post. For me, one of the most dangerous aspects of this issue with perception is texting and cellphone use behind the wheel. Coincidentally, the top post at Reddit as of this moment is a story about a driver getting rear ended due to someone texting and driving. This got me thinking that there must be an app for that. Sure enough, there are several:

Although I'm sure there would be a lot of issues to consider, I wonder if some of the features built into these apps shouldn't just be a part of the Operating System to begin with. Granted, a lot of users might be inordinately inconvenienced by some of the features, but the same could be said of seat belts as well and those have doubtlessly saved millions.

Logically you would think that large groups of people would be less susceptible to this type of blindness due to the "wisdom of crowds" phenomenon. Although if that were true, I don't think that we would have celebrity magicians playing before large audiences. So it would seem that there is a social dimension to this phenomenon as well and I don't think this has been lost on those in the world of Public Relations, Advertising, or Politics. Which is no doubt why it's pretty important to be aware of our common human weaknesses like this on a societal level, lest we be taken advantage of without even knowing what happened.

Anyway, sorry for the digression into some potentially thorny behavioral/social issues. I think there are obvious advantages to this aspect of attention as well. Like when you're out in public painting or sketching and there are a million different things going on, but somehow you're able to focus on what you need to in order to complete the work. It feels almost like meditation in that sense sometimes as you have to work so much harder at staying focused.

Evan said...

I think what the commercial is demonstrating is actually Change Blindness. "Change blindness is a surprising perceptual phenomenon that occurs when a change in a visual stimulus is introduced and the observer does not notice it. For example, observers often fail to notice major differences introduced into an image while it flickers off and on again." (

Inattentional blindness is a result of being overwhelmed to the point where you are unable to pay attention to all the stimuli in a situation. In the example video with the ball, viewers are focused so hard on counting the number of throws, that they miss everything else that is going on in the video.

James Gurney said...

Evan, I think you're right. That's a better description of what's going on. Unlike inattentional blindness, when the viewer is distracted by being overwhelmed with input, the viewer here is really focused on the task, but it's still difficult for all the reasons discussed.