[SOUND] If we think about control, we notice that there's something else that we can add to the mix, and that is, we can think about control in terms of flexibility. So think about the driver, someone who is driving, maybe looking at the car in front of them that's braking, maybe looking at a car behind them that's coming from the right, that's going to exit the freeway. At the same time that the person is looking at this, he or she may notice that his or her favorite song came on the radio and suddenly turn up the radio. And so, the ability to flexibly switch between these different types of information requires control. And so, control is not just for overcoming something or having to ignore the world, but it's also the ability to go back and forth between different types of information in real time. Now, the nature of control was uncovered by a very unlikely person. In 1927, Arthur Jersild did a series of studies, which he published in now very well cited paper, in which he looked at what happens when people are asked to switch between tasks. What is task switching? Well, think about the example that that Jersild used. So, he produced these number pairs that he would then put into a list and ask people to do a task with. So, he could ask them to subtract the two numbers. So, for example, six and four would be two. And he would give a list of numbers and ask them to subtract the second number from the first across the entire list. Then he could take another list of numbers and ask them to add the numbers. So, six plus four is ten. He created another list in which he asked people to add each number, and then he recorded the time it took them to do a list of subtraction and a list of addition. And in a final condition, he asked people to switch such that on the first number pair, they would have to subtract. On the second number pair, they would have to add. On the third number pair, they would have to subtract, and so on, and so forth. So they were switching between the two different tasks on every single number pair, and people in that condition were slower. This is a switching effect, what's called a task switching effect, which has been picked up by the literature again in the 70s, then in the 90s, and then more recently. And the idea is that when people have to switch between tasks, they slow down. The idea of switching and this literature made me think about driving while using a cellphone. My idea was that the reason that it was difficult to use a cellphone and drive was that somehow maybe what was happening is that people transported themselves somewhere else. So, let's say that I was talking to my mom, who lives in near San Francisco in the Bay area, and I was talking on the phone. And suddenly, I imagined that I was at my Mom's house. And instead of looking at the car in front of me, I was somehow split and thinking that I was at her house. And so, that's why it became so difficult to drive. Now interestingly, I was completely wrong. It turns out that in a set of studies done by Italian researchers, they found that, in fact, it didn't have anything to do with people transporting themselves away, that the easiest way to reduce the interference was to have people use a loudspeaker. So, when they played the telephone conversation away on a loudspeaker, then people didn't have as much interference when they were driving. So, what the problem is is not that I would transport myself to my mom. It's that my mom was in my ear. And in fact, other studies have found that, when you talk to someone in a car or when you listen to the radio, there's not as much of a problem as there is when talking on a cellphone. And some states in the US have suggested that you can use hands-free, have a mic in your ear, because it's your hands that's the problem. That's actually not true. The best thing is a loudspeaker. Why is that? Well, I explain to people, imagine that somebody was in the car with you, and they were talking in your ear, and you were driving. That would be incredibly distracting, [LAUGH] right? So, it's the same thing, right? And that's why it's distracting. It's the distance. It's the fact that the conversation is closer to us, and the driver is out there. The world is far away. And so, what's closer takes precedence. So in essence, we have to switch between what's close to us and what's far away. When we use loudspeakers, everything's far away. And so, it's easier for us to manage that and to, unfortunately, ignore the speaker, which is probably better for our safety.
