“The Invisible Gorilla” – Daniel Simons on the Limits of Perception

I’ve said it here before: the human mind is not infinite. We can’t perceive everything. Even those of us who realize this can still be surprised by just how limited our perception really is.

Daniel Simons has explored how our brain sifts through reality for the important bits, and how this can sometimes end up backfiring. Together with Christopher Chabris, he wrote The Invisible Gorilla: How Our Intuitions Deceive Us.

The book is based on an experiment he conducted, in which people failed to see a woman dressed up in a Gorilla costume.

Why? Here’s what he had to say on the subject.

The Interview

Thanks so much for talking to me, Daniel.

My pleasure.

I already know the answer, but I’m sure my readers would love to know why you called this book The Invisible Gorilla.

The book is named after a study I conducted with my co-author Christopher Chabris. In the study, we asked people to watch a video and to count how many times people wearing white shirts passed a ball while ignoring players wearing black shirts.

After about 30 seconds, a woman wearing a gorilla suit entered the scene, walked to the center, turned to face the camera, thumped her chest, and walked off. We found that approximately 50% of the participants in our studies failed to see the gorilla.

This phenomenon, known as inattentional blindness, illustrates the limits of perception and attention. When we focus attention, we often fail to notice other unexpected events. Although the video was created for our research, it went viral over the ensuing years. When Chris and I thought more about why it had gone viral, we realized that it was because the result is counterintuitive. People assume that they would notice something unexpected like a gorilla, and the video forces people to confront that mistaken belief.

The more we thought about that study and some of our other ones, we realized that people hold many mistaken intuitive beliefs about their own minds. That became a theme of our book: Our intuitions about the workings of our own minds are often wrong. The goal of our book was to explain why.

It’s easy to understand why that would have gone viral. Not only does it point out some surprising limits of our perception, it’s also pretty funny.

I’d like to hear about some of your research into the subject of “change blindness.” Besides your book, you’ve captured quite a bit of attention in the scholarly world for this research. How do we go about studying this, and what have we learned?

Change blindness is the surprising failure to notice a large change from one moment to the next. Like inattentional blindness, it reveals the limits of awareness. Unlike inattentional blindness, it reveals limits on our memory for what we’ve experienced and our ability to keep track of our world over time.

In order to detect a change, we have to remember how the world looked before the change and then compare that trace in memory to whatever came later. But we don’t see and remember everything around us, and we can’t compare all details over time automatically. The consequence is that we can miss large changes.

These limits are the reason why we often fail to detect continuity errors in movies, for example. As with inattentional blindness, most of us have the wrong intuitions about our memory. We tend to assume that we remember our world in much more detail and with much greater accuracy than we actually do.

That’s an interesting effect. Your mention of movies reminds me of something I was thinking about a few days ago. You would think that the way movies just cut from one angle to another, or even from one scene to another, without a transition should be jarring for the audience.

Instead it actually seems pretty natural. Perhaps that’s part of the reason we have change blindness, so that we’re not thrown off by every small change in our environment.

My colleague Daniel Levin and I have written on exactly that theme. To a large extent, movie perception capitalizes on the strengths and the limits of our visual system.

Very interesting.

So I’m always a bit fascinated about the ways that technology effects our behavior, both as individuals and as a society. You’ve done some research into the way that video games affect our perception of the world. I’d love to hear more about that.

My colleagues and I have been exploring the possibility that training with video games might improve other aspects of cognition. Most of the cognitive training literature shows that training typically doesn’t transfer to other tasks; you improve on the trained task, but the training doesn’t improve your performance on other tasks.

For example, doing crossword puzzles will make you better at crossword puzzles and might improve your vocabulary, but it won’t help you remember your friend’s name when you encounter her on the street.

Some early reports suggested that video games might be different. Ten hours of video game training improved performance on several basic cognitive tasks. We set out to replicate and extend those results, but we haven’t had much success.

We find that training on video games improves your performance on those games but the improvements don’t transfer to other measures of cognitive ability. Game training still holds promise because, unlike many other forms of training, games can be fun. But, they shouldn’t be viewed as a panacea for our cognitive limits.

Interesting. I recently came across a paper suggesting that video games are linked with creativity. I didn’t get a chance to see the actual peer reviewed literature, but from the article it did sound more like a correlation. In other words, it could just be that creative people are more likely to play video games.

Anyway, your book explores a lot of interesting subjects that don’t seem obviously related. You certainly wouldn’t think that chess masters had anything to do with criminals, or that this would be at all related to corporations who launch a product even when their own analysts know it’s going to flop. These mental issues are so ubiquitous that it’s easy to forget none of us are quite living in “reality.”

I wouldn’t draw that conclusion. We are living in reality. If we weren’t, our species never would have survived. Our brain evolved to help us accomplish what we need to (or, what we needed to at the time we evolved), and most of the time it gives us just the information we need.

The problem isn’t so much how we interact with the world or even with the limits on our cognition, but with our intuitions about those limits. If you think you’ll notice everything around you, you will put yourself in danger. However, if you realize that you have such limits, you can take steps to avoid the consequences.

That’s a great point. I overstepped a little.

Is there any way we can harness this knowledge and use it to our benefit? Or are we pretty much doomed to make these mistakes?

We’re stuck with these cognitive limits, but by learning about them, we can overcome some of our mistaken intuitions and compensate for our shortcomings.

So, at least when it comes to perception, improvement isn’t about our abilities, it’s about recognizing our limits.

Here’s something that interests me. A while back I discussed the nature of trade-offs, and how a “smarter” brain wouldn’t necessarily be a “better” brain. Do you think these limitations of perception are part of a trade-off?

They absolutely are a tradeoff. The reason we don’t notice the gorilla is that our minds are built to focus our limited attention resources on exactly what we are trying to do and see. Focused attention allows us to filter distractions and to work effectively.

The consequence is that we sometimes filter distractions that we might want to see. The problem comes not from the filtering, but from our mistaken belief that we aren’t filtering. More broadly, the brain is remarkably efficient given its limits. The vast majority of the time, it would be of little use to notice and remember everything.

Perception helps us to make sense of the world, and memory helps us use our experiences to predict the future. Both of those abilities are essential, and neither depends on seeing and remembering everything.

Again, the problem comes not from our capabilities or limits, but from our mistaken beliefs about those abilities and limits.

Take a look at Daniel’s book

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