Think about someone you've known forever. Maybe your best friend, more likely a sibling or parent. Think about what they looked like five years ago. Now, shake that mental Etch A Sketch and picture them 10 years ago. The mental images are probably not only similar, but also look an awful lot like the way you picture them today. (Unless they lost an eye in a wicked bar fight or something.) Of course, if you held a 10-year-old photo of them next to their face, changes would be substantial and evident.
This lack of mental accuracy isn't because you're a terrible partner or oblivious sibling. It happens all the time. A best friend doesn't always recognize the other's new facial piercing, and significant others don't always notice new haircuts. It's not that everyone's too self-involved. It's how our brains are wired.
"I have a colleague whose wife kept telling him he should shave his beard off," says J. Kevin O'Regan, the former director of the Laboratoire Psychologie de la Perception in Paris. "So, one day he was sitting at dinner with his family. And in the middle he left, shaved his beard off, and came back. Nobody noticed anything until the next day."
This is the result of change blindness. It's when we don't notice changes — even massive ones — despite them staring us directly in the face. It's the concept being exploited in those "Spot the Difference" games that used to frequent the back pages of magazines and still populate the screens of video games in the forgotten corners of sad dive bars. However, there's one vital ingredient in all cases of change blindness: Something has to momentarily obstruct the viewer.
In the beard example, the shaver left the room. That was the obstruction. Same thing when it comes to your friend's new piercing or your partner's new haircut. Bar video games have a few frames of black. In fact, there are three varieties of "obstructions" that work to cause change blindness: the flicker, the "mudsplash," and the gradual change over time. (Not noticing the changes in your friends/family over time is where that last one comes in.)
But these common obstructions aren't the only ways we miss big things. In the field of psychology, there's a similar concept called inattentional blindness. The results are the same (i.e., the viewer doesn't recognize a drastic change), but the key difference is that there's no blatant obstruction. Rather, we simply don't see the big difference because we're not looking for it. (There's an element of this happening in the shaved beard example as well; the family of the newly-shorn isn't expecting a change on that particular portion of the shavee's face, so they're not looking for one.)
Perhaps the most famous example of this is the 1999 video by psychologists Christopher Chabris and Daniel Simons. Why don't you just press play, and we'll reconvene afterwards:
In the case of the gorilla video — and if you're asking yourself "what gorilla video?" you're probably going to want to press play again — you're seeing only what the opening instructions told you to look for: the number of times that the people in white passed the ball. If you were instructed to look for the gorilla, certainly, you'd have seen that gorilla.
What's happening with these huge gaps in our ability to see obvious changes?
"When we see, we look onto the visual field and there's so much stuff out there," O'Regan says. "At any moment, you are only seeing what you are intending to. You interrogate the environment as though it's an external memory storage, as if you're extracting information about it."
To use O'Regan's external memory storage analogy, it's like having hundreds of gigs of music and movies on your computer's hard drive — to the point where the data slows down its processing power. Our brains work in the same way. If we were trying to process everything in front of us at once, it would be too much for us to handle. Rather than trying, the brain takes shortcuts by filling in the space we don't much care about. "Don't worry about noticing the beard," our brain tells us, "we all know it's right where it's supposed to be." Only when we care about noticing something particular do we focus and access the external memory storage.
"There would be an awful lot of stuff if we simultaneously activated everything that was out there outside of our brains," O'Regan says. "It's much easier for the brain to just assume."
(It's also how computer games construct the world that the player is inhabiting. At any moment, the game's only using its computing power to develop whatever scene the player's looking at, not the entire world of the game. And if you want to take this to its logical and extremely heady conclusion, let me introduce you to a NASA Jet Propulsion Lab scientist who believes that this concept proves we're all really living inside a computer simulation.)
"We labor under the illusion that seeing is seeing everything around us, when in fact, seeing is seeing mostly nothing at all," O'Regan says. "Seeing is asking yourself what is here and what is there." O'Regan uses the example of the refrigerator light. When you open it, the light's on, so you imagine the light's still on when you close the fridge, even though it isn't. Since you can't see everything at all times, your mind is filling in the blanks. "That gives you the illusion that everything is there. But actually, virtually nothing is there."
While this is all fun and low-impact nonsense for the most part — no one's getting truly hurt if you don't notice your friend's new nose piercing — the concepts do have real-world ramifications. For example, there are plenty of anecdotal accounts of inattentional blindness leading to car accidents. If you're not looking for gorillas, you'll miss them. Same thing happens if you're not consciously looking for, say, motorcycles.
"The person runs into the motorcycle, and they go to see the motorcyclist at the hospital, and the motorcyclist says, 'You were looking right at me, I could see it through your windscreen. And yet you just ran right into me,'" O'Regan explains. "And the driver says, 'Somehow I didn't see you.'"
There are other ramifications too. Film editors use these everyday blind spots to their advantage when every little hair on every actor's head isn't in the exact same place as the previous shots. (Continuity errors get spotted when filmmakers get a bit too lax.) Magicians use it all the time with their misdirection, as do their morally murky cousins, the pickpockets.
"Usually, when somebody puts his finger in your pocket, you feel stimulation on your leg," O'Regan says. "But if you have stuff in your visual field that attracts your attention, it masks the pressure on your pocket."
As far as how to train your mind to guard against this kind of thing — to always be on the lookout for gorillas, motorcyclists, and pickpockets — unfortunately, there's not much of an answer. "There will always be something I can show you that you won't be expecting," O'Regan says. "I think that it's ultimately a lost cause."
Next time your partner makes a stink about whether or not you've seen their new haircut, or are upset that you didn't notice their new beard shape, just forward them the gorilla video and wait for their apology.
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