Bet You Didn't Notice 'The Invisible Gorilla'

Gorilla And Man Reading Newspapers

The Invisible Gorilla by Christopher Chabris and Daniel Simons explores how we notice a lot less than we think we do. hide caption

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The Invisible Gorilla: And Other Ways Our Intuitions Deceive Us
By Christopher Chabris and Daniel Simons
Hardcover, 320 pages
Crown
List price: $27.00

Read An Excerpt

If you're intensely watching a ball game, and a gorilla walks onto the court, you'd notice him ... right? Believe it or not, there's actually a 50 percent chance you'd miss him entirely.

In their new book The Invisible Gorilla, Christopher Chabris and Daniel Simons explain how our brains trick us into thinking we see and know far more than we actually do.

The phrase, "the invisible gorilla," comes from an experiment created 10 years ago to test selective attention. In it, study participants are asked to watch a video in which two teams, one in black shirts and one in white shirts, are passing a ball. The participants are told to count how many times the players in white shirts pass the ball.

Mid-way through the video, a gorilla walks through the game, stands in the middle, pounds his chest, then exits.

Then, study participants are asked, "But did you see the gorilla?" More than half the time, subjects miss the gorilla entirely. More than that, even after the participants are told about the gorilla, they're certain they couldn't have missed it.

"Our intuition is that we will notice something that's that visible, that's that distinctive," explains Simons, "and that intuition is consistently wrong."

Follow-ups to the gorilla study confirmed the findings. "There are sort of whole categories of intuitions, which are not really to be relied on, and that you can go seriously astray by relying on," says Chabris.

"It's true that the kinds of faculties that our minds are filled with right now are very good at solving particular problems that they're designed by evolution to solve," Chabris allows. But today's world is a lot different from the world in which our minds evolved.

Things move much faster now, for example. "When our visual systems evolved, and when our capacities for attention evolved, we didn't move at 60 mph. down highways," so developing brains didn't need to be able to notice a lot of unexpected things approaching at high speeds.

Likewise, Chabris says, "our faculties for making decisions were able to rely on anecdotes and stories, when that was the only information that was available to us." Now that we have statistical studies and databases and all kinds of other information, we aren't as good at making sense of and using information as a guide in our decisions.

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NEAL CONAN, host:

This is TALK OF THE NATION. I'm Neal Conan in Washington.

If you're closely watching a basketball, and a gorilla walks right across the court, well, you'd think you'd notice, wouldn't you? Well, it turns out about half of us don't.

You'd think that experienced airline pilots coming in for a landing would see another plane blocking the runway, of course they would, except when they don't. And when you're stumped on a test question, you should just go with your gut, right? Well, sorry, if you're on a way to an exam right now, that snap response may not be the best idea.

Cognitive psychologists Christopher Chabris and Daniel Simons have spent their careers studying how our brains trick us into thinking we see and know much more than we actually do. Why we misremember important events but remain absolutely certain we're right and why our intuition so often fails us.

If you have a story of a snap decision gone wrong or a memory that turned out to be a little bit departed from reality, tell us your story. 800-989-8255 is the phone number. Zap us an email, talk@npr.org. You can also join the conversation on our website. That's at npr.org. Click on TALK OF THE NATION.

Later in the program, actor Bob Wisdom on the experience of landing a featured role on a weekly TV series and seeing it get canceled after week two.

But first, Christopher Chabris and Daniel Simons are the authors of "The Invisible Gorilla: And Other Ways Our Intuitions Deceive Us." Christopher Chabris is professor of psychology at Union College in New York. He joins us today from member station WGBH in Boston. Nice to have you with us?

Mr. Christopher Chabris (Co-author, "The Invisible Gorilla: And Other Ways Our Intuitions Deceive Us"): Thanks for having me.

CONAN: And Daniel Simons, also there in the studio with him in Boston. He's a professor of psychology at the University of Illinois. Thank you for being on the program.

Mr. DANIEL SIMONS (Co-author, "The Invisible Gorilla: And Other Ways Our Intuitions Deceive Us"): My pleasure. Glad to be here.

CONAN: And you both created your invisible gorilla experiment over 10 years ago to test what's called inattentional blindness. And I know I've sort of simplified the experiment a little bit, but what seems to be interesting is not that half the people don't notice it when they're supposed to be counting the number of passes made by the white team, but that indeed, even after they're certain they couldn't have missed it.

Unidentified Man #1: That's exactly right. It's both interesting because people fail to notice something that's so obviously vivid, but our intuition is that we won't notice that sort of a thing or our intuition is that we will notice something that's that visible, that's that distinctive, and that intuition is consistently wrong.

CONAN: Consistently wrong. Even when you made it, in effect, in another experiment - a red gorilla.

Mr. SIMONS: Well, essentially. That study was a follow-up to the original one, and rather than using basketball players and a gorilla going through the scene, we simplified it so we could have a little bit more control. And this was a study done by my former student, Steve Most(ph).

And in that study, you just following some white and black shapes moving around the scene, and as you're counting how many times, say, white shapes touch the sides of the display, a red cross goes through the middle of the scene. And there, we find that about 30 percent of people don't notice it.

In fact, when we first created that condition, it was labeled in our programming code as the cheat condition.

(Soundbite of laughter)

Mr. SIMONS: And the reason for that was we wanted to be able to make sure that the object was actually going through the display. So we figured, well, of course everybody would notice that, and we were wrong.

CONAN: And you were wrong. Indeed, one of the problems with your experiments is the fact that you suffer from these same tricks of mind, as well. Everybody does. It's the way we're wired.

Mr. SIMONS: That's right. In fact this is Dan, and I was just doing a study this past semester where I edited together a film, and we were making a change in the film, and I was fully convinced that the change was just way too big this time. And I was assuming that maybe 80 or 90 percent of people would notice it, and the study wouldn't work, and it turned out only 30 percent of people noticed it.

CONAN: And what was the change this time?

Mr. SIMONS: In this case, we were changing one person into another person across a change in view.

CONAN: The door experiment, yeah.

Mr. SIMONS: Yes, exactly, the same idea, just on video this time.

CONAN: And let me turn to Chris Chabris and say, in a lot of ways, it seems that this book is a bit of an answer to Malcolm Gladwell's book, "Blink."

Mr. CHABRIS: That's right. It didn't actually start out that way when we started writing the book, but we heard about how many people were seeing our gorilla experiment in all kinds of different contexts and it being used to make all kinds of different points.

We gradually came to the understanding ourselves, that the fact that people think they're going to see the gorilla, but they really don't, or they think they're going to see changes to people they're talking to, but they really don't remember them, is examples of a class of intuitions we have about our own minds that are sort of predictably wrong.

And we thought about it a little more, we realized that intuition, as a method of making decisions in general, has kind of been oversold a little bit lately, with books like "Blink" by Malcolm Gladwell and some others; and that there are sort of whole categories of intuitions which are not really to be relied on and which you can go seriously astray by relying on.

CONAN: Well, his fundamental thesis is that we evolved. The evolutionary psychology theory thesis - that we evolved to make rapid decisions very quickly, and that our evolutionary success suggests that, well, more often than not, we're right.

Mr. CHABRIS: Well, I wouldn't argue with that. It's true that the kinds of faculties that our minds are filled with right now, are very good at solving particular problems that they're very good at solving particular problems that they're designed by evolution to solve.

However, the world we live in today, is a lot different from the one that our minds evolved in. For one thing, things move much faster than they used to. When our visual systems evolved, and when our capacities for attention evolved, we didn't move at 60 miles per hour down highways - so we didn't really need to be able to notice a lot of unexpected things coming at us at high speeds. That's not true anymore.

Likewise, our facilities - our faculties for making decisions, we're able to sort of rely on anecdotes and stories when that was the only information that was available to us. Now we have statistical studies and databases and all kinds of other information that we're not quite as good at making sense of and using as a guide to our decisions.

CONAN: So it seems the unremarkable conclusion, Daniel Simons, is that if you're given the time to actually study the data and analyze the situation, you'd be best advised to take it.

Mr. SIMONS: For many sorts of situations, yeah. If you're making a complex decision about what stock to invest in or what car to buy, you're often going to be better off weighing all of the factors that matter, looking at Consumer Reports, for example, and looking at statistics - than in trusting your uncle Louie's recommendation.

That said, intuition's great for judgments that really don't lend themselves to that sort of analytic approach. So, for example, what kind of ice cream you like the most or who you find the most attractive. For those, no amount of deliberate analysis is really going to help much.

CONAN: Or if you find yourself in the unfortunate situation, fight or flight.

Mr. SIMONS: Absolutely. When you don't have time to react, you might as well...

CONAN: Go with the gut, right. And it's interesting that it's not merely the untrained observers that you tested on these, this attention. And this is only one of the tricks of intuition that you're talking about in the book - but the airline pilot experiment, where these were pilots being studied as they looked at the heads-up display as that was being introduced to commercial airliners some years ago.

And they were doing simulated landings on airfields and looking through the glass as opposed to glancing down at their instruments, and then every once in a while, the testers would put another airplane on the ground, right in their way, and they didn't see it.

Mr. SIMONS: That's exactly right. There was a nice study by Richard Hanes(ph), and it's been followed up over the years by people like Chris Wickens(ph) -doing exactly that.

You're in a flight simulator. These are commercial pilots, so pilots with often more than 1,000 hours of commercial flight experience, and in order to become a commercial pilot, they have to have had a lot of experience to begin with.

And in this sort of a flight simulator, if something unexpected happens, people often don't notice it. And you might think that this is a really rare event, and fortunately it actually is a pretty rare event, but this sort of example of an accident, an airline problem known as a runway incursion - a plane is on a runway where it doesn't belong - is actually the most common kind of dangerous situation in airplanes.

Mid-air collisions are extraordinarily rare. Collisions on the ground are extremely rare, but not as rare. They're the most common.

CONAN: And sadly, one in the Canary Islands was the worst aviation accident ever, when two 747s collided. Here's an email we have from Joe(ph): My brother, to this day, swears up and down, he remembers me having chicken pox when I was a baby.

He goes so far as to remember a specific time when I was taking a bath in oatmeal as a remedy for this. The only problem, this happened about a year before he was born. But beside my mother repeatedly telling him that he wasn't even alive for this, he still thinks he remembers it.

Mr. SIMONS: That's an excellent example of what cognitive psychologists call a source memory problem. So here the case is that you have a memory of the chicken box and the oatmeal bath - which sounds tasty - and you don't record correctly where this memory came from.

You think it came from your own experience, and you witnessed it with your own eyes, when in fact you heard it from someone else. And what we talk about a little bit in the book is this notion of the illusion of memory - that we think when we retrieve a vivid memory like that, and I'm sure that the listeners, you know, feels like it's very vivid and has a lot of detail to it and so on - but we sort of intuitively think when we retrieve something like that that it has to be accurate.

Where could all those details have come from, except for a true and accurate recording that was made at the time, sort of like if we pointed a video camera at that event and recorded it.

It turns our memory doesn't work that way. We can take details from lots of sources, information from lots of sources, and construct a memory out of them. And once we've retrieved it a few times and told the story, and here's one more time, he just told it to you, it's going to get stronger and stronger as a memory.

CONAN: Let's get another caller in on the conversation. This is Carolyn(ph), Carolyn calling from Akron, Ohio.

CAROLYN (Caller): Hi. I teach a forensic science course, and one of the first things we go over are eyewitness testimonies and how those can be really faulty. And one of the things that I was hoping maybe your guest could comment on, is the way we're wired, our brain likes to fill in the blanks.

So, even though we may not have witnessed something in an event, we - when we're recalling it, or depending on how we're questioned about it - we have a tendency to fill in, you know, things that maybe were just really suggestible. And one of the reasons why eyewitness testimony can be so hard to, say, you know, is it 100 percent accurate.

CONAN: Well...

CAROLYN: And oh, sorry.

CONAN: Let me just ask Christopher Chabris. One of the stories they describe in the book is a rape victim who was studying her rapist's face for the precise purpose of describing it to the police later and turned out to give utterly convincing testimony that convicted a man who didn't do it.

Mr. CHABRIS: Right. This is a famous case, now-famous case, I suppose, of Jennifer Thompson in North Carolina who was a rape victim. Her case is unusual for a number of reasons, one of them that she had the presence of mind during the attack to think about what happens if I escape, and the police need to catch this guy? I'm going to try to memorize his face and all the details of it as well as I can so that I can give them that information and they can track him down.

And she did exactly that, and they did a little bit of investigation and brought in a suspect, and she picked him in a lineup and so on. It went all the way to trial. She very confidently testified on the witness stand that he was her attacker, and he was sent to prison.

Only about 10 years later did DNA evidence conclusively exonerate him and show that it was someone else.

There are a couple of things going on in this case. One is a problem with memory, but another is a problem with confidence. She was told at the time, by the detectives in the case, that she was a model witness. They had never seen a better witness on the stand.

And the best eyewitness is a confident eyewitness because people in juries and other people involved in the case for that matter, the prosecutors, and so on, tend to believe confident people much more than unconfident people.

CONAN: Carolyn, thanks very much for the call.

CAROLYN: Thank you.

CONAN: Good luck with your class.

CAROLYN: Thanks.

CONAN: We're talking with Chris Chabris and with Daniel Simons about their book "The Invisible Gorilla: And Other Ways Our Intuitions Deceive Us." If you have an example of a story where your memory played tricks on you, you were absolutely convinced you were right, turned out you weren't, give us a call, 800-989-8255. Email us, talk@npr.org. Stay with us. I'm Neal Conan, TALK OF THE NATION, NPR News.

(Soundbite of music)

CONAN: This is TALK OF THE NATION. I'm Neal Conan in Washington.

We're talking with Chris Chabris and Dan Simons, co-authors of the book "The Invisible Gorilla." There's a story in the book that gives us insight into the way our memories work, or don't in some cases.

About 10 years ago, at a party Dan hosted, a colleague named Ken Norman(ph) told us a funny story about sitting next to the actor Patrick Stewart at a restaurant in Cambridge. Ken told us that Stewart had been dining with an attractive younger woman, who based on snippets of overheard conversation, appeared to be a publicist or agent.

For dessert, Stewart order baked Alaska. Toward the end of the meal, two members of the kitchen staff asked for his autograph, which he readily granted, but moments later a manager appeared and apologized, explaining that the Trekkie cook's action was against restaurant policy.

All those specific details remembered by their colleague, but they write: The only problem with that story was that it had actually happened not to Ken but to Chris.

(Soundbite of laughter)

CONAN: Chris, you were there in the restaurant?

Mr. CHABRIS: That's right. I was there. At least as far as my memory tells me, I was there, and Patrick Stewart was sitting at the next table over from me, and I'm not embarrassed to admit that I watch enough "Star Trek" to immediately recognize who he was and to pay attention to him, and I guess I must have told Ken this story later, and he liked it so much and liked Patrick Stewart so much that he sort of incorporated it into his own memory.

CONAN: Adopted the story as his own, and in total belief. If you'd given him a lie detector test, he would have sworn up and down he was telling the truth.

Mr. CHABRIS: I don't know about a lie detector test, but he told the story right in front of me at a party and quite proudly. So I think that if he had suspected that it might not be true, he wouldn't be spouting it off all over town.

CONAN: In front of the source, in front of the original source.

Mr. CHABRIS: Yeah, exactly, exactly. He seemed to be oblivious.

CONAN: We want our listeners with stories that turn out to be a little bit departed from reality or snap decisions gone wrong to give us a call, 800-989-8255. Email talk@npr.org. J.C. is on the line from San Antonio.

J.C. (Caller): Yes, thank you guys for taking my call.

CONAN: Go ahead.

J.C.: I had a similar source memory story gone awry. I was telling a friend a story about a dog that was walking down our street with a dead chicken in his mouth, and I told the story about where the dog was coming from, where it was heading to, the way the chicken looked.

And afterwards my girlfriend, who was standing next to me, said, um, you weren't there, I told you that story over the phone. You were out of town. And sure enough, I was. I had not actually been there when she saw this.

And my question for the psychologist is: Does the phone have anything to do with it? Did the fact that I heard the story through a non-visual means have any impact on my memory?

CONAN: You can ask your psychiatrist as well, but you're going to have to pay for that. This will be free.

J.C.: Oh good, good, yes.

Mr. SIMONS: This is Dan. It's actually an interesting insight. I don't know if the phone specifically has that much to do with it, but this sort of memory distortion was first studied, I think, most systematically by Bartlett(ph) in the 1930s, and he used a variant of the operator the telephone game, where you pass a message on to the next person, and then they pass it along to the person after that, and by the time you get through five or six people, the message is completely distorted.

His insight was that the same thing happens in our own minds, just on our own. Every time we tell a story, it gets slightly changed. It incorporates things that make sense. It incorporates it gets rid of things that didn't really make sense until the memory we're left with is a more coherent and meaningful version to us that makes sense to us. We're re-creating it each time we recall it.

I don't know whether hearing the story on the phone would actually amplify that, but certainly thinking about it and retelling it can lead you to incorporate it into your own memories and have you lose the source of the memory.

CONAN: It does suggest that maybe a red flag ought to go up every time you hear the phrase in the good old days.

(Soundbite of laughter)

Mr. CHABRIS: It also it makes you it should make you think also a little bit about how many times have you told a story as though it happened to you, when the person who it actually happened to wasn't standing there to tell you that that wasn't actually the case.

We only rarely find out that our memories are actually false. Most of the time we think they are entirely true, and nobody contradicts them.

CONAN: J.C., what was the moment like when you realized you'd been busted?

J.C.: Well, you know, it wasn't the first time that my girlfriend's kept me in shape, and it probably won't be the last either. So I was a little red-faced, but otherwise it was actually a better story being caught because now I have that story to tell you guys.

CONAN: All right.

(Soundbite of laughter)

CONAN: J.C., thanks, and make well, you might want to write this one down, give some documentation. Thanks very much for the phone call.

J.C.: I'll get the podcast.

CONAN: All right, bye-bye. Let's see if we can go next to this is Jeff, Jeff with us from Denver.

JEFF (Caller): Yes. Having a brother-in-law who's a psychiatrist who didn't trust repressed memories and having a lot of friends going through the repressed memories being brought up in the '90s, I decided to see what it was like with my own mind. I decided to plant memories deliberately, just to see if they felt real.

And it was bizarre. After just a few days they felt just like I had been there, even though I knew I was doing it to myself.

CONAN: This was the situation where children were recalling pretty much sexual abuse when they were at various daycare centers, and they were telling psychiatrists about this, and afterwards there was a lot of concern about what they felt might have been prompting, and the children might not have experienced this, were just telling the psychiatrist what they thought the psychiatrist wanted to hear.

But your experiment in planting, what kinds of memories did you plant in your own mind?

JEFF: It would be just something simple like an event with friends, sitting by a pool or something like that.

CONAN: And a couple of days later, even though you knew you'd planted it, it started to feel real.

JEFF: Exactly, yes. It was a very deliberate experiment, and it's really scary because, yeah, I hadn't trusted what a lot of friends were coming up with their repressed memories anyway. They just didn't feel right.

CONAN: Dan Simons, is that valid?

Mr. SIMONS: Sure. I haven't heard of people actually being able to successfully do it to themselves, but there's actually an extensive body of research. Probably the best-known person doing that is Beth Loftis(ph), and in her work she'll suggest something that might not have actually happened, and if you do it over and over again and ask people to kind of recall it as if it had happened, they gradually start to incorporate it into their own memories.

And there have been a number of great examples. The most recent one that I like a lot is giving people the suggestion that they went on a hot air balloon ride as a kid. And they make it even more vivid by doctoring a photograph, in which they insert the subject in the study as a child in a hot air balloon ride and ask them to recall it.

And over time people start to incorporate it and actually have more vivid memories. They recall details that weren't part of the photograph because they make them consistent with what would have happened.

CONAN: Jeff, thanks very much.

JEFF: Thank you.

CONAN: Dan, you were about to say something, or Chris?

Mr. CHABRIS: Oh, this is Chris, actually. I was going to say one thing our minds do seem to strive for is consistency. So one way that memories often change is to sort of make the whole story more consistent and sometimes also to make ourselves more at the center of the action: It happened to me instead of happening to somebody else.

CONAN: Let's go next to this is Ally(ph), Ally with us from Spanish Fork in Utah.

ALLY (Caller): Hi, how are you?

CONAN: I'm good, thanks.

ALLY: Good to be on the show. I wanted to tell you about my sister. I -frequently this happens with her, where she'll take on stories that I've told or that other people in the family have told or friends have told and retell them as if they're her own, as if it was her original knowledge or memory.

And at first it used to infuriate me, but now that we're having this discussion, I wonder if there are types of people, like physiologically, who are more susceptible to taking on other people's memories.

CONAN: Got any suggestions for that?

Mr. SIMONS: Well, there are a number of studies that look at suggestibility. I don't particularly know differences in personality that would lead some people to be suggestible than others. There's some evidence that young children can be particularly susceptible, which is partly why I think a lot of the repressed memory debate happened in the '90s, that many of those cases where children who were given leading questions and leading suggestions and very quickly incorporated those into whatever they were reporting; whether or not they incorporated them into their memories is hard to say. But at least what they were telling people happened - they took on the suggestions that they were being given. But everybody is subject to this to some degree.

ALLY: Is that a function of like, what's going on in the brain when that happens? Is there something that could be overdeveloped or underdeveloped in the brain?

Mr. SIMONS: Well, I would say that this actually a general process that happens to everybody, and we don't realize that it's happening. So we tend to think that memory works like a video camera, that we record everything in perfect detail and that our memory when we're recalling something is the same as playing it back from a tape. So what we're seeing is accurate and vivid. So it must be real.

And that's an illusion. It's not actually that detailed. We're reconstructing our memories based on what makes sense, what's consistent, what's coherent, what sorts of things we kind of would like to remember in that context. And our memories aren't a vivid record in absolute precision.

So just because we recall something vividly doesn't necessarily mean that it's any more accurate than something that we recall in a more sparse way.

ALLY: Do you think it has any connection to dreaming, like how the mind works when we dream?

Mr. CHABRIS: This is Chris talking. I have to say, first of all, I'm not an expert on dreams. So I don't want to go too far. But I think it's true that there's a lot of reconstruction and reconsolidation of memories and thoughts that's going on all the time that we're not really aware of.

Part of the process, part of the function of sleep is to consolidate memories and to help us learn new things. So I wouldn't be surprised if sleep and dreams were related somehow to that.

I would like to say one other thing, which is something you said very early in the call, was that you used to get infuriated when you heard these kinds of things, and now you don't.

That's kind of one of the messages we have in our book, is that when you're upset at the way someone else is behaving or when you notice something like this in your own behavior, it's best to first think that maybe it's some normal process of how the human mind works rather than deliberate lying and so on.

If people had thought that when Hillary Clinton said that she was under sniper fire in Bosnia rather than thinking oh, that must mean she's a liar, her campaign might have gone differently a couple of years ago.

CONAN: Ally, it may be those most susceptible to this sort of thing are siblings.

ALLY: Yeah.

(Soundbite of laughter)

ALLY: Great. I'm in for it.

CONAN: Okay. Thanks very much for the phone call.

ALLY: Thank you.

CONAN: Let's see if we can go next to Cleveland, and this is Andrew on the line.

ANDREW (Caller): Hi, Neal. Thanks for taking the call. I heard a very interesting bit of popular culture use of altering perception. It was an interview with James Cameron about his filmmaking process around about the time "Avatar" came out. And he said that he does a lot of his editing himself. So after finishing an editing sequence, in order to see the film as the average moviegoer will see it, he will sit down for - and watch the entire film, start to finish, in what he called a flop screen in which he takes the film that would have been left to right and flips the entire image of the film so he's watching it right to left. And what that does is it allows him to see the action sequences and the whole film basically with virgin eyes because he hasn't been watching it that - he's seeing like the mirror image of it and it tricks his brain into watching all those sequences come together for the first time.

CONAN: That's the way, of course, they got Gary Cooper as Babe Ruth to bat from the other side of the plate, as a left-hander. So anyway, that's an old story.

But this is the continuity problem and, indeed, one of the things you guys write about is the fact that most of us don't notice the continuity problems.

Prof. SIMONS: That's exactly right. So we feel like we do notice movies - movie mistakes, so I often would tell people who come into the lab when we're doing studies of motion picture perception and they would tell me, oh, I always notice errors in movies. And I can guarantee you that they don't because then they'd sit down and watch one of the videos that I or my colleagues and I made and not notice any of the changes.

The key is that we think we notice all the changes because we're only aware of the ones we've noticed. And we, of course, haven't noticed the ones that we missed. It's only when somebody calls attention to them that you can go in and spot them. But most of the time, we don't notice errors in movies. And, in fact, even the people who are on set and responsible for catching these sorts of mistakes, the script continuity or script supervisor...

CONAN: Mm-hmm.

Prof. SIMONS: ...what difference between them and the rest of us, for the most part, is that their intuitions are better. They know that they don't notice everything, so they focus attention on the things that actually matter in the scene, the things that people are likely to notice, and they take copious notes and use videos of the scenes to try and match things up. But...

CONAN: Used to be Polaroids in the old days, yeah.

Prof. SIMONS: Exactly. And handwritten notes and anything you could get as a prop for your memory because what script supervisors know is that memory is fallible. It's not going to be a precise record of what happened. You can't rely on it in the same way that you think you can.

CONAN: And my memory was clearly fallible. It was Gary Cooper who played Lou Gehrig in "Pride of the Yankees," not Babe Ruth. Anyway, both left-handed hitters. Andrew, thanks very much for the call.

We're talking with Dan Simons and Christopher Chabris about their book, "The Invisible Gorilla: And Other Ways Our Intuitions Deceive Us."

You're listening to TALK OF THE NATION from NPR News.

And one of our intuitions is, indeed, that we do try - our minds do try to make sense of things so that if A - if B follows A, then clearly A had something to do with B. You call that the narrative fallacy.

Prof. CHABRIS: Yeah. We also call it the illusion of cause, the idea being that we see things as causally related, one thing causing the other when we see them go together. And one of the ways things go together commonly is in sequence. One thing happens before another.

CONAN: Mm-hmm.

Prof. CHABRIS: And storytellers exploit this quite nicely by stringing together a series of facts and leading the reader to automatically infer that they're happening in some causal sequence, that they happen for a reason and filling in the blanks, in fact, between them to make up a coherent story. Those things are very powerful and they stick in our memory much better than let's say statistics or other kinds of information that people use to persuade, which don't really work nearly as well as stories, especially stories with emotional content.

CONAN: As somebody in the storytelling business, you're talking about my bread and butter here. You're explaining that, indeed, a lot of the times that A did not in fact cause B, in fact had nothing to do with it; nevertheless that this can seem very real.

Prof. SIMONS: Yeah, that's right. And in some ways it's an effective way to communicate. We communicate by remembering and telling stories. That's what the visual system and what our memory systems are designed to do, is make sense of what's happening around us, make it all meaningful, extract what's important around us and to make it coherent. And stories have that effect, particularly if they have a causal relationship. If they have one factor causing another, that's something that we can - kind of allows us to consolidate two facts into one.

CONAN: Mm-hmm.

Prof. SIMONS: And it makes it a really powerful way of telling stories. If instead of telling stories you just listed all the facts, it wouldn't be terribly interesting. It wouldn't be very memorable.

CONAN: Be Wikipedia. Anyway, let's go next to Gary, Gary with us from Athens in Ohio.

GARY (Caller): Yeah. Thanks for taking my call. I've got a question about - I do sports betting from time to time. And I've noticed that in the past that if I have an emotional attachment to the team, regardless of how much I feel, the - you know, the opposing team is going to win, I will still bet for the team that I like. And I was wondering if the emotional attachment - is that normal for it to outweigh the rational thought?

CONAN: Hmm. Did that come into your studies at all?

GARY: I'm sorry?

CONAN: No, I'm talking to the psychologist.

GARY: Oh.

Prof. CHABRIS: I think it's - as far as I know, it's entirely normal, and that's one of the problems in making good decisions, is separating out emotional tendencies and other sort of impulses, intuitive feelings we obvious - we automatically have about the situation or the gamble we're about to take from logical analysis.

And this is one thing when you're betting, you know, in a football pool or something like that. It's quite another thing when you're making million or billion dollar investments as a money manager, a hedge fund manager and so on. Then you really want to try to separate those things out and not rely on intuition as much and rely more on logical analysis and whatever solid information you can get. And professionals ought to be able to do that.

CONAN: And Professor, you examined a couple of different games, Dan Simons, chess and indeed poker. There's a poker aphorism: think long, think wrong. You suggest maybe people ought to take as much time as they can get.

Prof. SIMONS: Well, certainly for things like chess and poker, that makes a lot of sense. So a grandmaster chess player, somebody who's a true expert chess player, will be able to come up with very good decisions very quickly. But that's partly because through the amount of practice they've had, they've made - those intuitive judgments have become, or those deliberative judgments have become automatic so that what looks like a gut instinct to you or me is actually the result of automating a lot of deliberate careful thinking and recognizing patterns that have occurred over and over and over again that they had thought about over and over again. But I would trust a grandmaster's intuition about what to play in a chess position much more than my own.

CONAN: Mm-hmm. Gary, I hope you have an emotional attachment for the Lakers tonight.

GARY: I do.

CONAN: All right. Well, then I think you might be in good hands. Thanks very much for the phone call.

Simply an observation, not a recommendation. Dan Simons and Christopher Chabris, co-authors of the "Invisible Gorilla: And Other Ways Our Intuitions Deceive Us." You can read an excerpt from the book at npr.org. Click on TALK OF THE NATION. Thanks very much for your time today.

Prof. CHABRIS: Thank you.

Prof. SIMONS: Thank you.

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Excerpt: 'The Invisible Gorilla'

Cover Of 'The Invisible Gorilla'
The Invisible Gorilla: And Other Ways Our Intuitions Deceive Us
By Christopher Chabris and Daniel Simons
Hardcover, 320 pages
Crown
List price: $27.00

Chapter 1: "I think I would have seen that"

Around two o'clock on the cold, overcast morning of January 25, 1995, a group of four black men left the scene of a shooting at a hamburger restaurant in the Grove Hall section of Boston. As they drove away in a gold Lexus, the police radio erroneously announced that the victim was a cop, leading officers from several districts to join in a ten-mile high-speed chase. In the fifteen to twenty minutes of mayhem that ensued, one police car veered off the road and crashed into a parked van. Eventually the Lexus skidded to a stop in a cul-de-sac on Woodruff Way in the Mattapan neighborhood. The suspects fled the car and ran in different directions.

One suspect, Robert "Smut" Brown III, age twenty-four, wearing a dark leather jacket, exited the back passenger side of the car and sprinted toward a chain-link fence on the side of the cul-de-sac. The first car in pursuit, an unmarked police vehicle, stopped to the left of the Lexus. Michael Cox, a decorated officer from the police antigang unit who'd grown up in the nearby Roxbury area, got out of the passenger seat and took off after Brown. Cox, who also is black, was in plainclothes that night; he wore jeans, a black hoodie, and a parka.

Cox got to the fence just after Smut Brown. As Brown scrambled over the top, his jacket got stuck on the metal. Cox reached for Brown and tried to pull him back, but Brown managed to fall to the other side. Cox prepared to scale the fence in pursuit, but just as he was starting to climb, his head was struck from behind by a blunt object, perhaps a baton or a flashlight. He fell to the ground. Another police officer had mistaken him for a suspect, and several officers then beat up Cox, kicking him in the head, back, face, and mouth. After a few moments, someone yelled, "Stop, stop, he's a cop, he's a cop." At that point, the officers fled, leaving Cox lying unconscious on the ground with facial wounds, a concussion, and kidney damage.

Meanwhile, the pursuit of the suspects continued as more cops arrived. Early on the scene was Kenny Conley, a large, athletic man from South Boston who had joined the police force four years earlier, not long after graduating from high school. Conley's cruiser came to a stop about forty feet away from the gold Lexus. Conley saw Smut Brown scale the fence, drop to the other side, and run. Conley followed Brown over the fence, chased him on foot for about a mile, and eventually captured him at gunpoint and handcuffed him in a parking lot on River Street. Conley wasn't involved in the assault on Officer Cox, but he began his pursuit of Brown right as Cox was being pulled from the fence, and he scaled the fence right next to where the beating was happening.

Although the other murder suspects were caught and that case was considered solved, the assault on Officer Cox remained wide open. For the next two years, internal police investigators and a grand jury sought answers about what happened at the cul-de-sac. Which cops beat Cox? Why did they beat him? Did they simply mistake their black colleague for one of the black suspects? If so, why did they flee rather than seek medical help? Little headway was made, and in 1997, the local prosecutors handed the matter over to federal authorities so they could investigate possible civil rights violations.

Cox named three officers whom he said had attacked him that night, but all of them denied knowing anything about the assault. Initial police reports said that Cox sustained his injuries when he slipped on a patch of ice and fell against the back of one of the police cars. Although many of the nearly sixty cops who were on the scene must have known what happened to Cox, none admitted knowing anything about the beating. Here, for example, is what Kenny Conley, who apprehended Smut Brown, said under oath:

Q: So your testimony is that you went over the fence within seconds of seeing him go over the fence?

A: Yeah.

Q: And in that time, you did not see any black plainclothes police officer chasing him?

A: No, I did not.

Q: In fact, no black plainclothes officer was chasing him, according to your testimony?

A: I did not see any black plainclothes officer chasing him.

Q: And if he was chasing him, you would have seen it?

A: I should have.

Q: And if he was holding the suspect as the suspect was at the top of the fence, he was lunging at him, you would have seen that, too?

A: I should have.

When asked directly if he would have seen Cox trying to pull Smut Brown from the fence, he responded, "I think I would have seen that." Conley's terse replies suggested a reluctant witness who had been advised by lawyers to stick to yes or no answers and not volunteer information. Since he was the cop who had taken up the chase, he was in an ideal position to know what happened. His persistent refusal to admit to having seen Cox effectively blocked the federal prosecutors' attempt to indict the officers involved in the attack, and no one was ever charged with the assault.

The only person ever charged with a crime in the case was Kenny Conley himself. He was indicted in 1997 for perjury and obstruction of justice. The prosecutors were convinced that Conley was "testilying" — outlandishly claiming, under oath, not to have seen what was going on right before his eyes. According to this theory, just like the officers who filed reports denying any knowledge of the beating, Conley wouldn't rat out his fellow cops. Indeed, shortly after Conley's indictment, prominent Boston-area investigative journalist Dick Lehr wrote that "the Cox scandal shows a Boston police code of silence … a tight inner circle of officers protecting themselves with false stories."

Kenny Conley stuck with his story, and his case went to trial. Smut Brown testified that Conley was the cop who arrested him. He also said that after he dropped over the fence, he looked back and saw a tall white cop standing near the beating. Another police officer also testified that Conley was there. The jurors were incredulous at the notion that Conley could have run to the fence in pursuit of Brown without noticing the beating, or even seeing Officer Cox. After the trial, one juror explained, "It was hard for me to believe that, even with all the chaos, he didn't see something." Juror Burgess Nichols said that another juror had told him that his father and uncle had been police officers, and officers are taught "to observe everything" because they are "trained professionals."

Unable to reconcile their own expectations — and Conley's — with Conley's testimony that he didn't see Cox, the jury convicted him. Kenny Conley was found guilty of one count each of perjury and obstruction of justice, and he was sentenced to thirty-four months in jail. In 2000, after the U.S. Supreme Court declined to hear his case, he was fired from the Boston police force. While his lawyers kept him out of jail with new appeals, Conley took up a new career as a carpenter.

Dick Lehr, the journalist who reported on the Cox case and the "blue wall of silence," never actually met with Kenny Conley until the summer of 2001. After this interview, Lehr began to wonder whether Conley might actually be telling the truth about what he saw and experienced during his pursuit of Smut Brown. That's when Lehr brought the former cop to visit Dan's laboratory at Harvard.

Excerpted from The Invisible Gorilla And Other Ways Our Intuitions Deceive Us, by Christopher Chabris and Daniel Simons. Published by Crown. Copyright Christopher F. Chabris and Daniel J. Simons.

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