Climate change is already pausing problems for us today. But many worry less about themselves and more about their children. And that brings us to the fourth and final core example of this course, the developing minds of our kids or more specifically the development of what psychologists call our theory of mind, our ability to ascribe beliefs, desires, knowledge and intentions to ourselves and to others. Imagine this scene, you just left work and are on your way to meet a couple of friends for dinner. While walking to the restaurant you pass by a house with a box of books sitting outside. You peruse the titles and pick up a copy of the Spy novel, Tinker Tailor Soldier Spy. Now when you get to the restaurant, you see an empty building with the lights off. So you pick up your phone and you Google the restaurant and you see that it's not closed permanently, but just moved locations. Then you text your friends asking if they knew the restaurant had moved. One responds by texting back, going to be late then, sorry. When you finally get to the restaurant, you're the first one there. So you grab a table, the server brings you a menu and about half an hour later your two friends walk in. One of them says, geez, could you be on time next time please. Your friends laugh and you give them a hug and that's the end. Sounds like a pretty ordinary evening, right? On the surface it is, but it also contains many examples of our extraordinary inferential knowledge of other people's minds. How did you know the books were free? You inferred that the owners of the house left them out for people to take for free because that's a common practice in your neighborhood. How did you know to Google the restaurant's location and not just go home? Because you knew that there was more than one explanations for the empty building. How did you guess that your friends didn't know that the restaurant had moved? Well, because they never mentioned it to you when you were making plans and you had just been at the old location two weeks prior. How were you not confused by your friends' response to your text, which didn't directly answer your question? Well, you understood that implicit in their answer was that they didn't know. And how did the server know to bring you a menu when you sat down? Because he knew that that's what people expect when they go out to eat. And why didn't you get mad about your friend statement about being late? Because you knew she was being sarcastic. What you may not know however, is that very young children are largely incapable of making such complex inferences about what other people know and don't know. Scientists have studied this phenomenon using something they call the false belief task. There are many variations of this task, but a classic one uses candy. Here's how it works. A child is shown a box of a familiar brand of candy and asked what they think is inside. The child will often say the box contains candy. The research then opens the box and shows the child that it actually contains something else, say pencils. Then the child is asked what the box actually contains and they usually get it right. They say it contains pencils. Now up to this point in the experiment, both kids and adults would have responded the same way. But the next question researchers ask children shows where we part ways. When the researcher asks young children what they think other people would think is in the box, the children often say pencils. Adults on the other hand will say that other people will think that it's candy. Even more interestingly, it appears that there's an age at which children start responding more like adults, around three and a half years. From this experiment, researchers have concluded that children who are roughly this age or younger have a hard time separating reality from another person's perception of reality. In other words, they can't comprehend how someone could hold a false belief. They think others know what they know. There are many variations of this experiment. In another variation, researchers move an object from one location to another while a person's out of the room and they ask children where they think that other person will think the object is. Very young children will say they think the other person will think the object is in its new location. Not the old one. Now, there are even further variations of the tasks that put the validity of the original experiments conclusions into question. So in what researchers call the false photograph task, children are shown a camera on a tripod with an object like a teddy bear in its view. The experimenter acts as if she's taking a photo and then the teddy bear is replaced with another stuffed animal, say a duck. When asked what the photo will show, three-year-olds actually struggle to say that the camera would show a picture of the teddy bear when the duck was in front of the camera. In other words, the experiment had the opposite findings of the candy test. This variation has led some researchers to conclude young children have a more general inability to comprehend false beliefs. Not just that they can't attribute false beliefs to others. So what this tells us is that even when scientists agree on experimental results, they sometimes interpret these results differently. For many reasons studying children's minds is no easy task and researchers have to pay extra close attention to how they design their experiments with children. Children have cognitive limitations, they're easily distracted. And also ethics boards are extra strict when it comes to experiments with children.