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by Christopher Chabris, Daniel Simons. Reading this book will make you less sure of yourself—and that’s a good thing. In The Invisible Gorilla, Christopher Chabris and Daniel Simons, creators of one of psychology’s most famous experiments, use remarkable stories and. Reading this book will make you less sure of yourself—and that's a good thing. In The Invisible Gorilla, Christopher Chabris and Daniel Simons, creators of one. that's a good thing. In The Invisible Gorilla, Christopher Chabris and Daniel Simons, Buy the Audiobook Download: Apple · Audible · downpour · eMusic.

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the invisible gorilla And Other Ways Our Intuitions Deceive Us Christopher Chabris and Daniel Simons More Praise for the invisible gorilla "Should be required. Editorial Reviews. Review. Tom Vanderbilt Reviews The Invisible Gorilla Download it once and read it on your Kindle device, PC, phones or tablets. Use features like Kindle Store · Kindle eBooks · Politics & Social Sciences. Never doubt with our deal, since we will certainly constantly provide exactly what you require. As similar to this updated book The Invisible Gorilla: And Other.

Do you want to remove all your recent searches? Playing next. The Invisible Gorilla is a fascinating look at the unbelievable, yet routine tricks that your brain plays on you. In an award-winning and groundbreaking study, psychologists Christopher Chabris and Daniel Simons asked volunteers to watch a second film of a group of students playing basketball and told them to count the number of passes made. About halfway through, a woman dressed head to toe in a gorilla outfit slowly moved to centre screen, beat her chest at the camera, and casually strolled away. Unbelievably, almost half of the volunteers missed the gorilla.

The Invisible Gorilla is a fascinating look at the unbelievable, yet routine tricks that your brain plays on you. In an award-winning and groundbreaking study, psychologists Christopher Chabris and Daniel Simons asked volunteers to watch a second film of a group of students playing basketball and told them to count the number of passes made.

About halfway through, a woman dressed head to toe in a gorilla outfit slowly moved to centre screen, beat her chest at the camera, and casually strolled away. Unbelievably, almost half of the volunteers missed the gorilla.

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As this astonishing and utterly unique book demonstrates, exactly the same kind of mental illusion that causes people to miss the gorilla can also explain why many other things, including why: Sign in Continue with Facebook Continue with Google. No account yet? Sign up. For You Explore. George Orwell. To Kill a Mockingbird. Harper Lee. The Martian. Andy Weir. How to write a great review. The review must be at least 50 characters long. The title should be at least 4 characters long.

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Item s unavailable for purchase. Please review your cart. You can remove the unavailable item s now or we'll automatically remove it at Checkout. Remove FREE. Many people who have experienced the gorilla experiment see it as a sort of intelligence or ability test. The effect is so striking — and the bal- ance so even between the number who notice and the number who don't — that people often assume that some important aspect of your personality determines whether or not you notice the gorilla.

When Dan was working with Dateline NBC to create demonstrations, the show's producers speculated that employees in detail-oriented occupations would be more likely to notice the gorilla, and they asked most of their "subjects" what their jobs were. They assumed that how you perform on the task depends on what kind of person you are: If we could figure out whether some people consistently notice the gorilla and other unex- pected events in laboratory tasks, then we could figure out whether they are immune to inattentional blindness more generally, and potentially train the missers to become noticers.

Despite the intuitive appeal of the gorilla video as a Rosetta stone for personality types, there is almost no evidence that individual differ- ences in attention or other abilities affect inattentional blindness.

In theory, people could differ in the total attentional resources they have available, and those with more resources perhaps those with higher IQs might have enough "left over" after allocating some to the pri- mary task to be better at detecting unexpected objects. One argument against this possibility, though, is the consistency in the pattern of re- sults we obtain with the gorilla demonstration.

We conducted the orig- inal experiment on Harvard undergraduates — a fairly elite group — but the experiment works just as well at less prestigious institutions and with subjects who aren't students. In all cases, about half of the subjects see the gorilla and half don't. If you agree, you might also think that women would be more likely to notice the gorilla.

Unfortunately, there is little experimental evidence to support the popular belief about multitasking, and we haven't found any evidence that men are more prone than women to miss the gorilla.

In fact, the main conclusion from studies of multitask- ing is that virtually nobody does it well: As a rule, it is more efficient to do tasks one at a time rather than simultaneously. If indi- vidual differences in the ability to focus attention lead to differences in noticing unexpected objects, then people for whom the counting task is easier should be more likely to notice the gorilla — they are devoting fewer resources to the counting task and have more left over.

Dan and his graduate student Melinda Jensen recently conducted an experiment to test exactly this hypothesis. They first measured how well people could do a computer-based tracking task like the one we used in the "red gorilla" experiment and then looked to see whether those who performed the task well were more likely to notice an unexpected object.

They weren't. Apparently, whether you detect unexpected objects and events doesn't depend on your capacity for attention. Consistent with this conclusion, Dan and sports scientist Daniel Memmert, the re- searcher who tracked children's eye movements while they watched the gorilla video, found that who noticed and who missed an unexpected object was unrelated to several basic measures of attention capacity.

These findings have an important practical implication: Training people to improve their attention abilities may do nothing to help them detect unexpected objects.

If an object is truly unexpected, people are unlikely to notice it no matter how good or bad they are at focusing attention. As far as we can tell, there are no such people as "noticers" and "missers" — at least, no people who consistently notice or consistently miss unexpected events in a variety of contexts and situations.

But it is not a simple trait of the individual or a quality of the event; it is the combination of a fact about the individual and a fact about the situation in which the unexpected event occurs. Only seven people out of more than one thousand stopped to listen to Joshua Bell playing in the L'Enfant Plaza subway station.

One had been to a con- cert Bell had given just three weeks earlier. Two of the remaining six were musicians themselves. Their expertise helped them recognize his skill — and the pieces he was playing — through the din. The other, John Picarello, said, "This was a superb violinist. I've never heard anyone of that caliber.

He was technically proficient, with very good phrasing. He had a good fiddle, too, with a big, lush sound. Experienced basketball play- ers are more likely to notice the gorilla in the original basketball-passing video than are novice basketball players. In contrast, team handball players are no more likely to notice unexpected objects even though they are experts in a team sport that places demands on attention com- parable to those of basketball.

Put experts in a situation where they have no special skill, and they are ordinary novices, taxing their attention just to keep up with the primary task.

And no matter what the situation, experts are not im- mune to the illusory belief that people notice far more than they do.

Gene Weingarten described John Picarello's behavior as he watched Bell play: It just wasn't registering. That was baffling to me. Even within their field of specialty, experts are not immune to inatten- tional blindness or the illusion of attention.

Radiologists perform this visual detection task under controlled conditions every day of their careers. In the United States, their train- ing involves four years of medical school, followed by up to five years in residency at a teaching hospital.

Those who specialize in specific body systems spend another year or two in fellowship training. In total, they often have more than ten years of post-undergraduate training, followed by on-the-job experience in studying dozens of films each day. Despite their extensive training, radiologists can still miss subtle problems when they "read" medical images.

Consider a recent case described by Frank Zwemer and his colleagues at the University of Rochester School of Medicine. Doctors attempted to insert an intravenous line in a pe- ripheral vein, but failed, so they instead inserted a central line via a catheter in the femoral vein, the largest vein in the groin.

Getting the line in correctly requires also inserting a guidewire, which is removed once the line is in place. The line was introduced successfully, but due to an oversight, the physician neglected to remove the guidewire.

She was intubated for respiratory support, and a chest x-ray was taken to confirm the diagnosis and make sure that the breathing tube was placed correctly. The ER doctor and the attending radiologist agreed on the diagnosis, but neither of them noticed the guidewire.

The patient went next to the intensive care unit for several days of treatment, and after she improved she went to a standard unit.

There she developed shortness of breath, which was caused by pulmonary embolism — a blood clot in her lung. During this time she received two more x-rays, as well as an echocardiogram and a CT scan.

The patient then made a full recovery. It was determined later that the guidewire probably didn't cause the embolism because it was constructed of so-called nonthrombogenic material spe- cifically intended not to promote blood clotting. When the various medical images were examined afterward, the guidewire was clearly visible on all three x-rays and on the CT, but none of the many doctors on the case noticed it.

Their failure to see the anom- alous guidewire illustrates yet again the dangers of inattentional blind- ness. The radiologists and other physicians who reviewed the chest images looked at them carefully, but they did not see the guidewire because they did not expect to see it. Radiologists have a tremendously difficult task. They often review a large number of images at a time, typically looking for a specific problem — a broken bone, a tumor, and so on.

They can't take in every- thing in the image, so they focus their attention on the critical aspects of the image, just as the subjects in the gorilla study focused on counting the passes of one team of players. Due to the limits of attention, radiolo- gists are unlikely to notice aspects of the image that are unexpected, like the presence of a guidewire. But people assume that radiologists should notice any problem in a medical image regardless of whether it is ex- pected; any failure to do so must therefore be the result of the doctor's negligence.

Radiologists are regularly sued for missing small tumors or other problems. If you tell radiologists to find the guidewire in a chest x-ray, they will expect to see one and will notice it. But if you tell them to find a pulmonary embolism, they may not notice the guidewire. It's also possible that when searching for the guidewire, they will miss more pulmonary embolisms.

An unexpected tumor that was missed during the original reading might seem obvious in hindsight. Unfortunately, people often confuse what is easily noticed when it is expected with what should be noticed when it is unexpected. To reduce the effects of inattentional blindness, one can deliberately reexamine the same images with an eye toward the unexpected.

When participants in our studies know that something unexpected might happen, they consistently see the gorilla — the unexpected has become the target of focused attention. Devoting attention to the unexpected is not a cure-all, however. We have limited attention resources, and devoting some attention to unexpected events means that we have less attention available for our primary task.

It would be imprudent to ask radiologists to take time and resources away from detecting the expected problem in an x-ray "Doctor, can you confirm that this patient has a pulmonary embolism so that we can begin treat- ment?

A more effective strategy would be for a second radiologist, unfamiliar with the case and the tentative diagnosis, to examine the images and to look for secondary problems that might not have been noticed the first time through. So it turns out that even experts with a decade of training in their medical specialty can miss unexpected objects in their domain of ex- pertise.

Although radiologists are better able than laypeople to detect unusual aspects of radiographs, they suffer from the same limits on at- tention as everyone else.

Their expertise lies not in greater attention, but in more precise expectations formed by their experience and training in perceiving the important features of the images. Experience guides them to look for common problems rather than rare anomalies, and in most cases, that strategy is wise.

If this illusion of attention is so pervasive, how has our species survived to write about it? In part, inattentional blindness and the accompany- ing illusion of attention are a consequence of modern society.

Although our ancestors must have had similar limitations on awareness, in a less complex world there was less to be aware of. And few objects or events needed immediate attention. In contrast, the advance of technology has given us devices that require greater amounts of attention, more and more often, with shorter and shorter lead times.

Our neurological cir- cuits for vision and attention are built for pedestrian speeds, not for driving speeds. When you are walking, a delay of a few seconds in no- ticing an unexpected event is likely inconsequential. When you are driving, though, a delay of even one-tenth of a second in noticing an unexpected event can kill you or someone else.

The effects of inatten- tion are amplified at high speeds, since any delay in noticing happens at the highest speed. The effects of inattention are further amplified by any device or ac- tivity that takes attention away from what we are trying to do. Fortunately, accidents are still rare, because most of the time, nothing unexpected happens. But it is those rare unexpected events that matter. People are confident that they can drive and talk on the phone simultaneously precisely because they almost never encounter evidence that they cannot.

And by "evidence" we don't mean a news story about accident rates or a safety institute's latest report, or even a story of a friend who zoned out while driving and almost hit something. We mean a personal experience, like a colli- sion or a near miss, that was unambiguously caused by a depletion of attention and that cannot be explained away as the other person's fault a rationalization we are as good at making as we are at overestimating our own levels of attention.

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We will almost never be aware of the more subtle evidence of our distraction. Drivers who make mistakes usually don't notice them; after all, they're distracted. The problem is that we lack positive evidence for our lack of attention. That is the basis of the illusion of attention.

We are aware only of the un- expected objects we do notice, not the ones we have missed. It takes an experience like missing the chest-thumping gorilla, which is hard to ex- plain away and which we have little incentive to explain away , to show us how much of the world around us we must be missing.

If the mechanisms of attention are opaque to us, how can we elimi- nate inattentional blindness so that we can be sure to spot the gorilla? The answer isn't simple. In order to eliminate inattentional blindness, we would effectively have to eliminate focused attention. We would have to watch the gorilla video without bothering to focus on counting passes or even to focus on what we found interesting in the display.

We would have to watch the display without expectations and without goals. But for the human mind, expectations and goals are inextricably intertwined with the most basic processes of perception and are not readily extin- guished.

Expectations are based on our prior experiences of the world, and perception builds on that experience. Our experience and expecta- tions help us to make sense of what we see, and without them, the visual world would just be an unstructured array of light, a "blooming, buzz- ing confusion" in the classic words of William James. If we pay more attention to one place, object, or event, we necessarily pay less attention to others. Inattentional blindness is thus a necessary, if unfor- tunate, by-product of the normal operation of attention and perception.

If we are right that inattentional blindness results from inherent limits on the capacity of visual attention, it might be impossible to reduce or eliminate it in general.

In essence, trying to eliminate inattentional blindness would be equivalent to asking people to try flying by flapping their arms really rapidly. The structure of the human body doesn't per- mit us to fly, just as the structure of the mind doesn't permit us to con- sciously perceive everything around us. The issue of how best to allocate our limited attention relates to a larger principle of attention. For the most part, inattentional blindness isn't a problem.

In fact, it is a consequence of the way attention works; it is the cost of our exceptional — and exceptionally useful — ability to focus our minds. Most drivers follow the rules of the road, most doctors don't leave guidewires in patients, most fishing vessels aren't floating right above submarines, most planes aren't guided in to land right on top of other planes, most cops don't viciously beat suspects, and most world-class violinists don't play in the subway And gorillas rarely saunter through basketball games.

Unexpected events are unex- pected for a good reason: They are rare. More important, in most cases, failing to spot the unexpected has little consequence.

Attention Writ Large The illusion of attention affects us all in both mundane and potentially life-threatening ways — it truly is an everyday illusion.

It contributes to everything from traffic accidents and airplane cockpit displays to cell phones, medicine, and even subway busking. As the gorilla experiment has become more widely known, it has been used to explain countless failures of awareness, from the concrete to the abstract, in diverse do- mains. It's not just limited to visual attention, but applies equally well to all of our senses and even to broader patterns in the world around us. The gorilla experiment is powerful because it forces people to confront the il- lusion of attention.

It provides an effective metaphor precisely because the illusion of attention has such broad reach. Here are some examples: Within the realm of visual perception, noticing suffers from even more limitations than the ones we have discussed so far.

For example, it is hard to look for multiple things at once, to distinguish similar- looking objects, and to remain vigilant over long periods of time per- forming the same task. Our underappreciation of these constraints can have dire consequences for our safety and security. We expect airport baggage scanners to spot weapons in luggage, but they regularly fail to notice contraband items planted by authorities during tests of security procedures.

The task of security scanners is much like the task of radiologists though the training is, shall we say, much less extensive , and it is difficult if not impossible to see everything in a briefly viewed image. That's especially true given that the things being searched for are rare. Lifeguards have the nearly impossible task of scanning a large expanse of water and detecting the rare event of some- one drowning.

The lifeguards simply cannot see everything, but the illusion of attention makes us believe they will. Only becoming aware of the illusion of attention can help us to take steps to avoid missing what we need to see. In some cases, like lifeguard- ing, technological innovations such as automated scanning could help.

Without awareness of our limitations, though, technological interven- tion can hurt. Head-up displays might improve our ability to navigate and to keep our eyes on the road, but they might impair our ability to detect unexpected events. Similarly, in-car GPS navigation systems might help us find our way, but when trusted implicitly, they can lead us to drive without noticing where we are going. Twice in , drivers in New York State blindly followed their GPS instructions and turned onto a set of train tracks in front of an on- coming train neither was injured, fortunately.

A driver in Britain caused a train crash after unwittingly driving onto the Newcastle-Carlisle rail line tracks. A more common problem in Britain occurs when truck drivers fol- low their GPS commands onto streets that are too small for their trucks. In one case, a driver wedged his truck so firmly into a country lane that he couldn't move backward, move forward, or even open his door.

He had to sleep in his cab for three days before being towed out by a trac- tor. The problem, of course, is that the navigation system doesn't know or take account of the size of the vehicle — and some of us don't know that it doesn't know. In April , rising waters made a ford through the start of the Avon River temporarily impassable, so it was closed and markers were put on both sides.

Every day during the two weeks following the closure, one or two cars drove right past the warning signs and into the river.

Technology can help us to overcome the limits on our abilities, but only if we recognize that any technological aid will have limits too. If we misunderstand the limits of the technology, these aids can actually make us less likely to notice what is around us. In a sense, we tend to generalize our illusion of attention to the aids we use to overcome the limits on our attention. In the next chapter, we will consider this ques- tion: If we successfully pay attention to something and notice it, will it then be remembered?

Most people think yes, but we will argue that this too is an illusion — the illusion of memory. He was a four-time national coach of the year, led the Olympic gold medal basketball team that featured future NBA stars Michael Jordan and Pat- rick Ewing, and won three national collegiate titles as the coach of the Indiana University Hoosiers. He was famous for running a "clean" basket- ball operation: His organizations were never accused of the sorts of re- cruiting violations that plague many top-tier basketball programs, and the majority of his players completed their college degrees.

He was a coaching innovator whom many of his former players credit for their personal and professional successes. Despite this unparalleled record of achievement, Bobby Knight was fired from Indiana University in September after an undergraduate yelled "Hey, Knight, what's up?

That Knight's dismissal was triggered by a lecture on respect is ironic.

How Our Intuitions Deceive Us

Throughout his coaching career, Knight had a national reputa- tion for a volatile temper, crass behavior, and a disdainful attitude to- ward the press and others. He was the sub- ject of a Saturday Night Live parody in which Jim Belushi played a high school chess coach who knocked over an opponent's pieces and yelled at his own player, "Move it!

Move it! Move the bishop! It was considered a firing offense only because of a report published earlier that year that had led the university to adopt a zero-tolerance policy for his future indiscretions.

It focused on an inci- dent described by Neil Reed, one of Knight's former players.

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Reed was a star recruit, a high school Ail-American who scored an average of about ten points per game during his three years at Indiana.

During a practice in , Knight confronted Reed for failing to call out a team- mate's name when making a pass, but Reed stood his ground against Knight, claiming he had in fact yelled the name.

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According to Reed, Knight then physically attacked him: At that point coach thrust right at me, just came right at me, wasn't far away enough to where I couldn't see it coming, was close enough to come at me and reach and put his hand around my throat.

He came at me with two hands but grabbed me with one hand. People came in and separated us like we were in a school yard to fight. He had me by the throat for I would probably say that little situation lasted about 5 seconds. I grabbed his wrist and started walking back and by this time people, coaches Dan Dakich, Felling grabbed coach Knight and pulled him away. The national reporting of this incident caused a sensation and led Indiana officials to shorten their coach's leash.

Reed's account vividly confirmed Knight's stormy reputation and put it in an even darker light. But shortly after the Sports Illustrated report, other people present at the time told a different story. I question anything Neil Reed says. I might have grabbed the guy and moved him over. I mean, if you choke a guy, I would think he would need hospitalization. But how, ex- actly, do we think it works? Before answering this question, we'd like you to try a brief memory test.

Read through the following list of words: We'll get back to them in a few paragraphs. Most of us cannot remember a fifteen-digit number, and we know that we cannot, so we do not even try. We all sometimes forget where we put our car keys or our car , we fail to recall a friend's name, or we neglect to pick up the dry cleaning on the way home from work.

And we know that we often make these mistakes — our intuitive beliefs about such everyday memory failures are reasonably accurate. Our intuitions about the persistence and detail of memory are a different story.

In the national survey of fifteen hundred people we commissioned in , we included several questions designed to probe how people think memory works. It is impossible to disprove this belief — the memories could in principle be stored somewhere — but most experts on human memory find it implausible that the brain would devote energy and space to storing every detail of our lives espe- cially if that information could never be accessed.

Why do people easily grasp the limita- tions of short-term memory, but misunderstand the nature of long-term memory?

This chapter is about how our memories can mislead us and how our beliefs about the workings of memory are mistaken. The illu- sion of attention happens when what we notice is different from what we think we notice. The illusion of memory happens when what we remem- ber is different from what we think we remember. Now we'd like you to try to recall all of the words from the list you read. Do your best to recall as many as you can. Write them down on a piece of paper before you continue reading.

What could be simpler than recalling a list of words that you read only moments ago? Not much, but even a task as simple as this reveals systematic distortions in memory. Look at the list you wrote down. How do you think you did? Most likely, you didn't recall all fifteen words. When we use this task as a classroom demonstration, most students recall a few words from the beginning of the list and a few from the end of the list.

Stop to think about this for a moment. Those words were all utterly common and familiar, you were not under any special stress we hope when you read them, and there was no time pressure when you had to recall them.

If you ask a small child to remember a short list of words for a few minutes, you will notice that as late as age four kids still don't appear to realize that they need to exert special effort to keep the words in memory.

As adults, though, we have learned that there are limits to how much we can maintain in memory for a short time.

When we have to remember a phone number long enough to dial it, we repeat it to our- selves, either silently or out loud, as long as necessary. Once an arbitrary list is longer than the "magic number" of about seven items, most people have trouble holding it in their short-term memories. When we have to remember any- thing more than this, we use memory crutches notepads, voice recorders, and so on to help. The reason your difficulty recalling all fifteen words in our list illus- trates the illusion of memory is not that it reveals limits on how much we can remember.

People generally understand those limits. It reflects the illusion of memory because it highlights how we remember what we do. Take a look at the list of words you recalled. Does it contain the word "sleep"? About 40 percent of the people reading this book will recall having seen the word "sleep. You might even have a distinct recol- lection of seeing it on the list — but it wasn't there.

You fabricated it. Memory depends both on what actually happened and on how we made sense of what happened. The list you read was designed to produce just this type of false memory. All of the words are closely associated with the missing word "sleep. At some level, you knew that they were all related to sleep, but you didn't take special note of the fact that "sleep" was not on the list. Then, when you recalled the words, your mind reconstructed the list as best it could, based on both your specific memory for the words you saw and on your knowledge of how the words were generally related.

When we perceive something, we extract the meaning from what we see or hear, or smell. It would be an uncharacteristic waste of energy and other re- sources for evolution to have designed a brain that took in every possible stimulus with equal fidelity when there is little for an organism to gain from such a strategy.

Likewise, memory doesn't store everything we perceive, but instead takes what we have seen or heard and associates it with what we already know. These associations help us to discern what is important and to recall details about what we've seen. They provide "retrieval cues" that make our memories more fluent. In most cases, such cues are helpful. But these associations can also lead us astray, pre- cisely because they lead to an inflated sense of the precision of memory.

We cannot easily distinguish between what we recall verbatim and what we construct based on associations and knowledge. The word-list example, originally devised in the s by psychologist James Deese and then studied extensively by Henry Roediger and Kathleen Mc- Dermott in the s, 5 is a simple way to demonstrate this principle, but memory distortions and the illusion of memory extend well beyond arbitrary lists of words.

Just as the gorilla experiment showed that people see what they expect to see, people often remember what they expect to remember. They make sense of a scene, and that interpretation colors — or even determines — what they remember about it. In a dramatic demonstra- tion of this principle, psychologists William Brewer and James Trey- ens conducted a clever experiment using a simple ruse.

In most respects, the waiting room was a typical graduate student office, with a desk, chairs, shelves, and so on. Almost all of the subjects recalled such common objects. Thirty percent of them also recalled seeing books, and 10 percent recalled seeing a file cabinet. But this office was unusual — it contained no books or file cabinets. In the same way that people tended to recall having seen the word "sleep" when remembering a list of words associated with sleep, their memory reconstructed the contents of the room based both on what actually was there and on what should have been there.

If you look at a picture of the office, it will probably seem perfectly normal until some- one points out what's missing, and then it will suddenly start to look strange.

What is stored in memory is not an exact replica of reality, but a re-creation of it. We cannot play back our memories like a DVD — each time we recall a memory, we integrate whatever details we do re- member with our expectations for what we should remember. One of them had a dis- torted memory for the event, but which one? In most cases of disputed memory like this, there's no definitive way to determine who was right and who was wrong.

What makes this example particularly interesting is that well after Reed, Dakich, and others went public with their ac- cusations and memories, a videotape of the practice surfaced. It showed Knight approach Reed, grab him by the front of the neck with one hand for several seconds, and push him backward.

Other coaches and players stopped what they were doing and watched. Nobody came to rescue Reed.

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No assistant coaches separated them. Reed correctly re- called that Knight had grabbed him by the throat, at least momentarily, but over time, in his mind, the memory was elaborated and distorted. And, to Reed, his totally false memory of being forcibly separated from Coach Knight was just as real as his more ac- curate memory of being choked.

I know what happened and that [tape] proves what happened. I think the moment after something like that, especially a year-old kid being in that situation, I don't think you can find fault in a little bit of I mean.

I'm not lying. That's how I remember the thing happening and [former assistant coach Ron] Felling's five feet from me. As far as people coming in between, I remember people coming between us. Before the tape surfaced, Knight told HBO's Frank Deford that he didn't remember choking Reed, and added, "There isn't anything that I have done with one kid that I haven't done with a lot of other kids.

His memory for the event was distorted to be- come consistent with his broader beliefs and expectations for what hap- pens at practices: Coaches grab kids and move them around, showing them where to stand and what to do.

Physical contact, for Knight, is a regular part of coaching. He misremembered the event as being less con- sequential than it was, distorting it to be more consistent with his own beliefs about typical coaching situations. For Reed, this event likely was far more consequential. As he noted, he was a "twenty-year-old kid" at the time and he probably hadn't been grabbed by the neck often in practice. To him, it was a jarring and unusual event, one that he stored in his memory as "coach choked me.

For Knight, the incident was just like another arbitrary word in a list. For Reed, the incident had a powerful meaning, and the details were filled in accordingly.

It's not unreasonable to think that memories can fade and morph over the years, and that they can be influenced by the motives and goals of the rememberer.

But what if two people witness the exact same incident, and the delay before they have to describe it is no more than the length of time spent on hold waiting for a operator?

They drove their Camry north on Fourteenth Street and stopped at a traf- fic light at the intersection of Rhode Island Avenue.

Tyce, a writer on education policy, was driving. His wife, Leslie, who had recently earned a law degree at Yale, was in the pas- senger seat. To her right, Leslie saw a man riding a bicycle down the sidewalk in their direction. Suddenly, seemingly out of nowhere, another man approached the cyclist, pulled him off the bicycle, and began stabbing him repeatedly.

Leslie heard the victim scream. She grabbed her cell phone and dialed , only to be greeted by a voice saying, "You have reached the emergency service, all lines are busy, please hold. Leslie described what she saw as they continued driving with the traffic down Fourteenth Street.

The victim was a man in his twenties or thirties rid- ing a bicycle.