Читать книгу The Invisible Gorilla: And Other Ways Our Intuition Deceives Us - Christopher Chabris - Страница 11

Imagine that you are driving home from work, thinking about what you will do when you get there and everything you left unfinished at the office. Just as you begin to make a left turn across a lane of oncoming traffic, a boy chases a ball into the road in front of you. Would you notice him? Maybe not, you should now be thinking. What if, rather than being lost in thought while you were driving, you were talking on a cell phone? Would you notice then? Most people believe that as long as their eyes are on the road and their hands are on the wheel, they will see and react appropriately to any contingency. Yet extensive research has documented the dangers of driving while talking on a phone. Both experimental and epidemiological studies show that the driving impairments caused by talking on a cell phone are comparable to the effects of driving while legally intoxicated.³⁵ When talking on a cell phone, drivers react more slowly to stoplights, take longer to initiate evasive maneuvers, and suffer from generally reduced awareness of their surroundings. In most cases, neither drunk driving nor driving while talking on a cell phone lead to accidents. In part, that is because most driving is predictable and lawful, and even if you aren’t driving perfectly, the other drivers are trying not to hit you. The situations in which such impairments are catastrophic, though, are those that require an emergency reaction to an unexpected event. A slight delay in braking might make the difference between stopping short of the boy in the street and running him over.

For the most part, people are at least familiar with the dangers of talking on a cell phone while driving. We’ve all seen distracted drivers run a stop sign, obliviously veer into another lane, or drive at 30 mph in a 45 mph zone. As columnist Ellen Goodman wrote, “The very same people who use cell phones…are convinced that they should be taken out of the hands of (other) idiots who use them.”³⁶

The realization that (other) people are unable to drive safely while talking on the phone led to a movement to regulate the use of handheld cell phones while driving. New York was one of the first states to pass such legislation. The law banned the use of handheld phones while driving, based on the intuition that taking our hands off the wheel to use the phone is the main danger posed by talking while driving. In fact, the New York legislation provided for tickets to be waived if drivers could prove that they subsequently purchased a hands-free headset. Not surprisingly, the telecommunications industry supported the New York bill and regularly promotes the safety and advantages of hands-free headsets. A flier from AT&T Wireless proclaims, “If you use your wireless phone while driving, you can keep both hands on the wheel,” and a similar brochure from Nokia ranks using a hands-free device whenever possible as second on their list of ten safety recommendations. In our survey, 77 percent of Americans agreed with the statement, “While driving, it’s safer to talk on a hands-free phone than a handheld phone.” The assumption underlying these beliefs and claims as well as most laws on distracted driving—that as long as you are looking at the road, you will notice unexpected events—is precisely the illusion of attention. Given what you now know about the gorilla experiment, you can probably guess what we will say next.

The problem isn’t with our eyes or our hands. We can drive just fine with one hand on the wheel, and we can look at the road while holding a phone. Indeed, the acts of holding a phone and turning a steering wheel place little demand on our cognitive capacities. These motor-control processes are almost entirely automatic and unconscious; as an experienced driver, you don’t have to think about how to move your arms to make the car turn left or to keep the phone up to your ear. The problem is not with limitations on motor control, but with limitations on attentional resources and awareness. In fact, there are few if any differences between the distracting effects of handheld phones and hands-free phones. Both distract in the same way, and to the same extent.³⁷ Driving a car and having a conversation on a cell phone, despite being well-practiced and seemingly effortless tasks, both draw upon the mind’s limited stock of attention resources. They require multitasking, and despite what you may have heard or may think, the more attention-demanding tasks your brain does, the worse it does each one.

In a second part of our original gorilla experiment, we tested the limits of attention by making the task of the subjects (counting basketball passes) more difficult. Rather than just a single count of the total number of passes made by the white team, we asked people to keep two separate mental counts, one of aerial passes and one of bounce passes (but still focusing on the white team). As we predicted, this increased by 20 percent the number of people missing an unexpected event.³⁸ Making the counting task harder requires people to devote more attention to it, leaving fewer mental resources available to see the gorilla. As we use more of our limited attention, we are that much less likely to notice the unexpected. The problem is with consuming a limited cognitive resource, not with holding the phone. And most important, as the incredulous reactions of our study participants demonstrate, most of us are utterly unaware of this limit on our awareness. Experiment after experiment has shown no benefit whatsoever for hands-free phones over handheld ones. In fact, legislation banning the use of handheld phones might even have the ironic effect of making people more confident that they can safely use a hands-free phone while driving.

One could argue that our gorilla experiment isn’t really comparable to the scenario of driving while talking on a cell phone. That is, increasing the difficulty of the counting task as we did might increase the burden on attention more than a cell phone conversation would. There’s an easy way to account for this possibility, though: Do an experiment! To explore the effects of cell phone conversations on inattention directly, Brian Scholl and his students at Yale used a variant of the “red gorilla” computerized task described earlier and compared a group who performed the task as usual with one that performed it while simultaneously carrying on a cell phone conversation.³⁹ In their particular variant of the task, about 30 percent of the participants missed the unexpected object when they were just doing the tracking task. However, participants who performed the task while talking on a phone missed the unexpected object 90 percent of the time! Simply having a conversation on a phone tripled the chances that they would fail to see something unexpected.

This sobering finding shows that cell phone conversations dramatically impair visual perception and awareness. These impairments are due to the limits of attention and not due to the nature of the phone; even though both tasks seem effortless, both demand our attention. Intriguingly, the cell phone conversation didn’t impair the subjects’ ability to do the tracking task—it just decreased their chances of noticing something unexpected. This finding may explain why people falsely think that cell phones have no effect on their driving: People are lulled into thinking that they drive just fine because they can still perform the primary task (staying on the road) properly. The problem is that they’re much less likely to notice rare, unexpected, potentially catastrophic events, and our daily experience gives us little feedback about such events.

If you’re like many people who have heard us speak about inattention, cell phones, and driving, you may wonder why talking to someone on a phone should be any more dangerous than talking to the person in the passenger seat, which doesn’t seem objectionable. (Or, if you have responded enthusiastically to our arguments—and thank you for doing so—you may be getting ready for a campaign to make “driving while talking” illegal, no matter whom you are talking to.) It may come as a surprise, then, to learn that talking to a passenger in your car is not nearly as disruptive as talking on a cell phone. In fact, most of the evidence suggests that talking to a passenger has little or no effect on driving ability.⁴⁰

Talking to a passenger could be less problematic for several reasons. First, it’s simply easier to hear and understand someone right next to you than someone on a phone, so you don’t need to exert as much effort just to keep up with the conversation. Second, the person sitting next to you provides another set of eyes—a passenger might notice something unexpected on the road and alert you, a service your cell-phone conversation partner can’t provide. The most interesting reason for this difference between cell-phone conversation partners and passengers has to do with the social demands of conversations. When you converse with the other people in your car, they are aware of the environment you are in. Consequently, if you enter a challenging driving situation and stop speaking, your passengers will quickly deduce the reason for your silence. There’s no social demand for you to keep speaking because the driving context adjusts the expectations of everyone in the car about social interaction. When talking on a cell phone, though, you feel a strong social demand to continue the conversation despite difficult driving conditions because your conversation partner has no reason to expect you to suddenly stop and start speaking. These three factors, in combination, help to explain why talking on a cell phone is particularly dangerous when driving, more so than many other forms of distraction.