你的记忆也会欺骗你?

当你走进一个房间时，你是否记得你见过的所有东西？即便是我们很注意力很集中，我们还是会被我们的记忆所欺骗，这是为什么呢？本期节目中我们邀请了心理学家克里斯托弗凯伯瑞斯和和丹尼尔西门来为我们一一解谜。

FLATOW: You're listening to SCIENCE FRIDAY. I'm Ira Flatow. We're talking this hour about how our brains pay attention with my guests, Christopher Chabris and Daniel Simons, author of "The Invisible Gorilla: And Other Ways our Intuitions Deceive Us."

FLATOW: Let's talk about multitasking is everywhere in the news because people are doing, they're doing, they're tweeting at same time they're typing. They're listening to our show on the radio. They're driving. Is it a fallacy that we're able to multitask? And which one of you want to take that?

Dr. CHABRIS: It's a fallacy that we're able to multitask and do two or three or four or five things just as well as we could do them if we did them one at a time.

The problem is that we don't really get the sense of how badly we're performing these multiple tasks at once, and we think we're doing them just fine.

This is, for example, one of the reasons why some people talk on the cell phone while they're driving because they don't get the sense that they're driving less well than they actually are. They don't get the sense that they're missing unexpected things because, of course, they don't see what they're missing.

And that's part of the power of the gorilla experiment, actually, is it sort of shows you vividly what you're missing when you're focused on one task, and it gives people an insight that they don't necessarily get in everyday life when they're multitasking around and don't notice the mistakes they're making or the errors they might be making.

FLATOW: Daniel, have anything to add to that?

Dr. SIMONS: Yeah, I was going to say one of the other interesting aspects of this is that people often don't really know what they mean by multitasking. So there are different forms of multitasking.

You can have a whole bunch of things to do and be thinking about all of them and switching among them, doing one at a time, and that's very different from trying to do two things at exactly the same time.

So you can think about this like trying to talk and chew gum and whistle at the same time. You can't do all three because your mouth is necessary for all of them and in different ways.

Well, the same's true of our mind. If you're trying to do two things at the same time that require the same cognitive skill or ability, you just can't do both at the same time as well.

FLATOW: How good are we at paying attention to any one thing? Are we designed to do that, or because, you know, we have all this peripheral vision that we're always on the lookout for something else, the jungle mentality, coming out of that jungle.

Dr. SIMONS: Well, I think there's probably a range of individual differences in how well people can stay focused on one thing. But it does seem that our attention system, the way our mind works, is designed to help us focus on one thing and to filter out things that we don't care about.

It's just a side consequence of that is we sometimes filter out things that we might care about if we knew they were there.

FLATOW: Is there any one way to get you to focus better, any situation you should put yourself in? One kind of thing I have seen in this generation, meaning the last 20 years, it's certainly true of my kids, they say they focus better with music, while listening to music or doing their homework, which was, you know, absolutely the opposite. My parents would never let me have the TV on or listen to music. But is there any truth to that claim that they can focus better with that kind of distraction?

Dr. SIMONS: As far as I'm aware, there is no truth to that claim.

(Soundbite of laughter)

Dr. SIMONS: However, I'm not surprised that kids would make the claim that they can focus on lots of things at once and that music helps them and that the TV in the background doesn't distract them and so on because there's something about the way our minds are constructed, you know, teenage minds, adult minds, whatever, that keeps us somewhat out of touch with how well we're performing tasks on a moment-by-moment basis, and we very easily convince ourselves we're doing things well and that certain conditions are good for performance when in fact we don't have a lot of insight into how well we're doing things.

This leads to phenomena like overconfidence. We don't really know how well we've doing various things. So it's not surprising that people would say, oh, yeah, I can do things really well with all the stimuli I like coming at me all the time.

FLATOW: But what about soothing, classical music in the background? I mean, I know you worked with the Mozart Effect. Tell us about that.

Dr. SIMONS: Well, the idea of the Mozart Effect, which came on the scene in the early 1990s, didn't have so much to do with background music, although people may have took it that way. It had to do with listening to classical music, specifically Mozart's music, right before taking a test.

And the claim was that if you listen to 10 minutes of Mozart's music and then took an IQ test, you would score nine points higher, and that's really a lot in IQ-test terms. That's like going from, like, you know, a C student to a B-plus or something like that. Wow, 10 minutes of Mozart's music, that's all it takes.

It turns out that many people tried to reproduce that same effect and failed, and there probably is no Mozart Effect, or it's just an artifact of you hear music you like, it puts you in a slightly better mood, and it's good to be a good mood when you take a test. You don't want to be in a bad mood when you're taking a test, no evidence that it really sort of fundamentally changes the brain or re-organizes the way your neurons or anything fancy like that.

FLATOW: Talking with the authors of "The Invisible Gorilla," and let's go to the phones, to Michael(ph) in San Antonio. Hi, Mike.

MICHAEL (Caller): Good afternoon, gentlemen.

FLATOW: Hi there.

MICHAEL: I'm a police captain, and when I was an instructor at the academy, of course you want police officers to be very aware of everything that's going on around them. And we used to use the gorilla test for our cadets the very first week of training.

And they were always shocked and amazed at how little they were able to see when someone else came into the room to speak to the instructor. For maybe 30, 60 seconds, the individual left the room, and then the instructor would turn to the class, start asking questions about identifying the person that just left the room.

And in most cases, well over 90 percent of the class couldn't tell you what color hair he had, whether he was six-foot tall or four-foot tall. And it really comes as a shock to them for them to realize how little they were aware of the individual, and it kind of shocks them into a situation where they become hypersensitive, after that class, of everything that's going on around them.

FLATOW: Gentlemen, do you have a comment?

Dr. SIMONS: Yeah, this Dan. I think it's fantastic that you're using this sort of video and this sort of demonstration for that purpose. And I think you tapped into exactly what's interesting about this sort of effect, which is that it's counterintuitive.

When you realize what you've just missed, it's jarring because it forces you to confront the fact that you actually aren't noticing everything. And that's particularly true for professions like police work, where the people who are going into police work kind of pride themselves on being attentive and noticing and looking very carefully and being able to spot everything.

And the reality is nobody can. It's just a limit of our minds work.

FLATOW: What about the eyewitnesses who supposedly can remember what happened at the scene?

Dr. SIMONS: Well, that's the real danger, that we tend to assume that we're going to see things and remember them accurately, and that when we recall those details that they're just as accurate as if we were replaying the event for ourselves like a videotape.

FLATOW: Michael, did you do the second part of the test on our website today?

MICHAEL: Yes, yes we do.

FLATOW: Don't give it away. Did you notice the difference?

MICHAEL: I did.

(Soundbite of laughter)

Dr. SIMONS: You're among the rare few.

MICHAEL: I was looking for something, and I knew it had to be there. So I was probably more attentive than your average individual.

FLATOW: Do you find with your officers that you can train them to be more attentive after they see that test?

MICHAEL: Oh, absolutely, yeah. And we find that they practice it, especially during their time at the academy. We're talking about a 16-week course, and of course, every once in a while, you know, you get a little surprise test based on their acuity.

Yeah, each and every one of them, when questioned individually, you can see an improvement from week to week because they are very much paying attention where they hadn't been before.

FLATOW: Well, thank you very much for calling, Captain. Have a good weekend.

MICHAEL: My pleasure.

FLATOW: Bye-bye.

Dr. CHABRIS: That's a really interesting point. There's actually surprisingly little evidence that you can train these abilities to the point that you can actually notice everything.

What you can do, and that's likely what's going on in this sort of training, is you can train people to look for particular kinds of things.

So script supervisors, the people who work on movie sets, know how to look for particular kinds of mistakes that might end up into a movie that would be noticed, and they look for specifically, and they ignore the other stuff that's never going to matter or the stuff that's never going to end up across a cut.

What they know that most people don't is that their memory is lousy, that they can't rely on their memory, and they know to take all sorts of notes and keep careful track of the things that are likely to matter.

FLATOW: Let's see if we can get one more question from Ray(ph) in Sacramento. Hi, Ray.

RAY (Caller): Hi, I was going to ask you to speak about the small number of people who actually can pass the test consistently.

FLATOW: Yeah, that's a good question, Dan?

Dr. SIMONS: Let's let Chris do that one.

FLATOW: Okay, Chris?

Dr. CHABRIS: If you mean the small number of people who actually notice the gorilla, it turns out, as far as we've been able to figure out, and Dan has done research on this and so have others, there is no thing that predicts consistently who is going to notice and who isn't going to notice.

That's one of the most common questions that we get after people see this video is, if they notice, they say, well, what does that say about me? Or if their brother didn't notice, then they say, well, am I smarter than him or something? And the answer is, as far as we can tell, no.

It's circumstance and chance and the particular environment and background and what's going on in your head when you see it.

It's not an intelligence test. It's not that much of a personality test, and we don't believe that there are people who consistently always notice these things. It's basically a feature of the human mind that we all share, and we might miss this stuff at any given point.

FLATOW: So is there a general overall theme or message of your research or you book, "The Invisible Gorilla"?

Dr. SIMONS: Yeah, I think the overall theme of our book is that the intuitions we have about the workings of our mind, they're based on our experiences. They're based on our day-to-day experience of the world. But that day-to-day experience of the world and of our own minds is misleading, and it can lead us to conclusions about how our minds work that isn't right.

So if you're multitasking, you don't realize how distracted you are. You don't realize the impact it has on you. If you're driving and talking on the cell phone, you don't realize how distracted you are, and that applies to memory and confidence and reasoning and our beliefs about how we think and decide.

FLATOW: Interesting book, gentlemen. I want to thank you for taking time to be with us today.

Dr. CHABRIS: Thanks for having us.

FLATOW: Good read, "The Invisible Gorilla: And Other Ways Our Intuitions Deceive Us," Christopher Chabris and Daniel Simons. Thanks again.

Dr. SIMONS: Thanks.