experiments by Ian Walker, a psychologist at the University of Bath in England. In a complex system such as traffic, Walker says, where myriad people with a loose sense of the proper traffic code are constantly interacting, people construct “mental models” to help guide them. “They just develop their own idea of how it works,” Walker told me over lunch in the village of Salisbury. “And everyone’s got different ideas.”
Take the case of a car and a bicycle at an intersection. As it happens, studies consistently show intersections to be one of the most dangerous places for cyclists (not to mention cars) in traffic. Some of the reasons have to do with visibility and other perceptual problems; these will be addressed in Chapter 3. But even when drivers do see cyclists, things are not so simple. In one study, Walker showed “drivers” (i.e., qualified drivers in a lab) a photograph of a cyclist stopped at an intersection who was gazing toward the cross street but not making a turn signal with their arm. When drivers were asked to predict the cyclist’s next move, 55 percent said the cyclist was not going to turn, but 45 percent said the opposite. “This is what I mean about the informality of people’s mental models,” he said. “There are a lot of informal signals on the road that are being used. In that study you’ve actually got half the population taking it to mean one thing and half the population taking it to mean another thing—which is crying out for accidents.”
But there’s something even more interesting than mere misinterpretation going on here, Walker suggests. In another study, Walker presented subjects (again, qualified drivers in a lab) with photographs of a brightly clad bicyclist in a number of different traffic situations in a typical English village. Using a computer, the subjects were asked to “stop” or “go” depending on what they thought the cyclist was going to do at various intersections. Cyclists were shown making a proper turn signal with the arm, giving a glance or a look over the shoulder, or not signaling at all. Results were tallied on the number of “good outcomes” (when the driver made the right choice), “false alarms” (the driver stopped when they did not have to), and what Walker predicted would be collisions. As might be expected (or hoped), drivers tended to sound false alarms most often when a cyclist looked over their shoulder or gave no signal at all. As they did not know what the cyclist was going to do, they behaved over-cautiously. But when Walker studied the “collisions,” he found that these happened most often when the cyclist had given the most clear indication of all, an arm turning signal. What’s more, when drivers made the correct decision to stop, their reaction times were slowest when they were confronted with the arm signal.
Why should proper signaling, even when it’s seen and understood by the driver, be more linked to danger in this study than lack of signaling? The answer may be that the cyclists are guilty of simply looking like humans, rather than anonymous cars. In a previous study, Walker had subjects look at various photographs of traffic and describe what was going on. When subjects saw a photograph with a car, they were more likely to refer to the photo’s subject as a thing. When subjects looked at a picture that showed a pedestrian or a cyclist, they were more likely to use language that described a person. It somehow seems natural to say “the bicyclist yielded to the car,” while it sounds strange to say “the driver hit the bicycle.” In one photograph Walker showed, a woman was visible in a car, while a man on a bike waited behind. Although the woman could be clearly seen in the car, she was never referred to as a person, while the cyclist almost always was. Even when she was visible she was rendered invisible by the car.
In theory, this is good news for bicycle riders: What cyclist does not want to be
Take the case of a car and a bicycle at an intersection. As it happens, studies consistently show intersections to be one of the most dangerous places for cyclists (not to mention cars) in traffic. Some of the reasons have to do with visibility and other perceptual problems; these will be addressed in Chapter 3. But even when drivers do see cyclists, things are not so simple. In one study, Walker showed “drivers” (i.e., qualified drivers in a lab) a photograph of a cyclist stopped at an intersection who was gazing toward the cross street but not making a turn signal with their arm. When drivers were asked to predict the cyclist’s next move, 55 percent said the cyclist was not going to turn, but 45 percent said the opposite. “This is what I mean about the informality of people’s mental models,” he said. “There are a lot of informal signals on the road that are being used. In that study you’ve actually got half the population taking it to mean one thing and half the population taking it to mean another thing—which is crying out for accidents.”
But there’s something even more interesting than mere misinterpretation going on here, Walker suggests. In another study, Walker presented subjects (again, qualified drivers in a lab) with photographs of a brightly clad bicyclist in a number of different traffic situations in a typical English village. Using a computer, the subjects were asked to “stop” or “go” depending on what they thought the cyclist was going to do at various intersections. Cyclists were shown making a proper turn signal with the arm, giving a glance or a look over the shoulder, or not signaling at all. Results were tallied on the number of “good outcomes” (when the driver made the right choice), “false alarms” (the driver stopped when they did not have to), and what Walker predicted would be collisions. As might be expected (or hoped), drivers tended to sound false alarms most often when a cyclist looked over their shoulder or gave no signal at all. As they did not know what the cyclist was going to do, they behaved over-cautiously. But when Walker studied the “collisions,” he found that these happened most often when the cyclist had given the most clear indication of all, an arm turning signal. What’s more, when drivers made the correct decision to stop, their reaction times were slowest when they were confronted with the arm signal.
Why should proper signaling, even when it’s seen and understood by the driver, be more linked to danger in this study than lack of signaling? The answer may be that the cyclists are guilty of simply looking like humans, rather than anonymous cars. In a previous study, Walker had subjects look at various photographs of traffic and describe what was going on. When subjects saw a photograph with a car, they were more likely to refer to the photo’s subject as a thing. When subjects looked at a picture that showed a pedestrian or a cyclist, they were more likely to use language that described a person. It somehow seems natural to say “the bicyclist yielded to the car,” while it sounds strange to say “the driver hit the bicycle.” In one photograph Walker showed, a woman was visible in a car, while a man on a bike waited behind. Although the woman could be clearly seen in the car, she was never referred to as a person, while the cyclist almost always was. Even when she was visible she was rendered invisible by the car.
In theory, this is good news for bicycle riders: What cyclist does not want to be
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