So, how do we make these discoveries about the minds of babies? Well, there are different methods. Right now, a lot of scientists are very excited about the idea of using neuroscientific methods, machinery that can scan a baby's brain as the baby is looking at some display or ruminating about something. As you can imagine, this is in some way the most elegant possible way of exploring the mental life of a creature who can't yet talk or tell you what he or she is thinking. This work is very exciting and is going on. But, over last couple of decades, infant psychologists have explored different methods that could tell you what a baby is thinking that don't require this sort of brain waves scanning. The methods employ the use of the two things babies can do, even very young babies. They could suck on a pacifier, for instance, and they could look. They could control where their eyes go. These methods human use to explore what babies know. So, take sucking. Suppose you wanted to know whether a baby really enjoyed listening to sound of her mother's voice as opposed to the sound of another person. Well, you can't ask but what you could do is stick a pacifier in a baby's mouth, put headphones on the baby's ears, and now when the baby sucks on a pacifier, the baby gets to listen to her mother's voice, or in another condition listen to a stranger's voice. You could use this method to discover whether or not babies prefer their mother's voice, and so they do. Or you could use this method, for instance, discover whether babies preferred not to listen to their native language. So, a baby born to English-speaking parents, do they prefer English over Russian? A baby born to Russian speaking parents, do they prefer Russian over English? I'll talk about these studies more when we get to language in the next lecture. But that's how the method of monitoring babies sucking behavior can tell you something about how they think and understand the world. Probably, the dominant method that people have used to study the minds of babies is looking. This exploits certain factors about about how babies minds work. They kind of work like ours. So, imagine you're sitting down and there's a dog in front of you and a cat in front of you, dog on the right, cat on the left, and you heard the word dog, dog, dog. You'd naturally look towards the dog. If we did that with you, that would show that you knew what a dog was, you know the English word dog was, and you could do the same thing with a baby. Similarly, if you looked at something for a while and it was doing some interesting things, sooner or later you get bored. The term psychologists uses, you would become habituated. By telling what bores you, we can tell something about the sort of distinctions that you make and the sort of understanding that you have. So, imagine this. Imagine we were to show you a series of pictures of blue things, different shades of blue, blue, blue, blue, blue, blue. Sooner or later, you start to drift off. Suddenly, we started to show your green things, green, green, green, green, green, you'd probably perk up. You'd say, "This is something new." So, you'd start looking again. Now, what can this tell us? Well, you wouldn't be able to do this if you weren't able to distinguish blue from green. Or as a more interesting example, suppose I was to show you a picture of two dogs, then two cups, then two tables and so on and so forth. Then suddenly I was to show you three cats, and three monkeys, and three shoes, you might perk up or you might not. But if you perked up, this will suggest you could tell the difference between two things and three things because you're saying, "Here's something different." I'm giving adults as an example, but it should be clear we can use these same studies for babies both to discover their sensory capacities, for instance, can they distinguish different colors? But also their broader conceptual capacities including questions like, can they tell the difference between two things and three things? Another way in which looking time can tell you about the contents in somebody's mind, is that we look longer at things that surprise us. Imagine you were staring at a man and he gradually placed a hat on top of his head, okay, whatever. But now imagine you were looking at a man and he held a hat on his hand, and the hat gradually floated upwards and landed on his head, you'd stare. Why? Well, that tells us something about you, which is that you expect people to do things like put hats on her head. But the idea of a hat floating on its own volition is surprising. It violates your expectations. So, we can use that sort of method with a baby to ask, what does a baby expect of the world and what surprises it? In some of the classic studies looking at early baby understanding have used this method. So, take this example. Imagine you were to see this, you were to see sort of a brick, and then something sliding back and forth behind it. Because you don't see the middle, all you see is the top sliding back and forth and the bottom sliding back and forth, and so this is logically compatible of two possibilities. One possibility as in B, which is that there's a whole stick there. Another possibility as in C, what you just see is the top and the bottom. Now, C is more compatible with what you're seeing. To infer B, requires making inference about what's behind the brick, that there's a singular object. But you'd be surprised at C. You kind of laugh. It's like a joke. While B is exactly what you'd expect. Turns out babies reason the same way. This is a problem for the view that babies lack object prominence because they're inferring the presence of an object even though it was invisible. Or take this study. Baby stare at a block, and then a screen rises and obscures the block. Now, suppose it's true that babies believe out of sight, out of mind. That for babies, if you can't see something, it no longer exists. Then maybe should expect that screen to keep falling because there's no block to get in its way. But when you do create exactly that scenario by removing a block through a trap door, babies are surprised as if they are reasoning, "Hey, there should have been a block there to stop the movement of the screen." Babies think like you do, which is contrary to Piaget. That objects continue to exist even after they're out of sight. So, there's been a lot of studies on the physical world, looking at babies understanding of objects are solid, that they obey the rules of gravity, that it traveled through space in continuous pass, that they move when something else bumps into it. These studies find that by the time a baby hits his or her first birthday, the baby possesses some considerably rich physical knowledge. Other studies look at numerical knowledge. I'm going to show you this brief video clip from the work of Yale psychologist Karen Wynn, who's had to say my wife, looking at babies understanding of number. This film will show you the sort of studies that were done, and the sort of methods that were used and a quite extraordinary findings that these studies yielded. The first experiment involves addition. Six month Abigail is placed in front of a stage. Great. We'll, first I'm going to introduce you to a couple of things about our state, has a solid box- Like in a magic show, she's introduced to the actors and set. Watch the screen. She is shown one toy. Then two toys. Then Abigail's addition skills are tested. She's shown the equation of one toy, plus another toy. When the screen comes down there are two toys. But what happens when she's shown something impossible. One toy disappears behind the screen and is joined by a second one. When the screen comes down there's only one toy. Something doesn't add up, Abigail stares in disbelief as if she knows that this isn't the correct answer. As the scenes alternate between possible and impossible, Abigail responds accordingly. Staring longer at the impossible and quickly getting bored with the correct answer. Next comes subtraction. For this, another six month old Connor is brought in to test his skills. He's shown two toys. One toy is taken away. He's left to make his own calculations, but when the screen comes down there are still two toys. Connor looks perplexed. It's definitely not what he expected. Great job. All right, we're going to get set for the next one back here. Next, there's a change. Two toys. Up goes the screen and look. Take away one. Where is he going? This time there's only one toy left. Connor quickly loses interest because there's nothing engaging in something so obvious. Like in Abigail's experiment with addition, Connor's attention is only attracted when the subtraction doesn't compute. This suggests to the researchers that even at six months of age, babies may have a rudimentary sense of numbers. So, we've talked about babies understanding of the physical world and of number, but now consider babies understand is social world of other people. We've long known that babies have some sort of social adaptations. For instance, they orient toward shapes that look like faces, like the one on the left as opposed to ones that don't, like the one on the right. But more recent studies have found an even richer and more sophisticated knowledge and I think it's particularly cool. At Yale University, scientists have designed an ingenious experiment. They wanted to see if babies are born, good or bad. Hundreds of parents have volunteered their children. The two scientists behind the project are Karen Wynn and Paul Bloom. I would give a year of my life to spend five minutes as a baby, to be able to recapture what it feels like to me that sort of creature. Men trust in origin of morality, the origin of good and evil. We want to see what people start off with, do they start off with a moral sense or they start off with good impulses, do they start off evil impulses. Then, when you have a sense of that, you could ask yourself, how does this develop into the adult sense of right and wrong, the adult moral behavior? They wanted to find out what is in the baby's brain. To try and unlock the secret, they devised a kind of morality play that each baby will watch. So, this character has a ball that he's playing with and he passes it to this other fellow, who returns it in a nice reciprocal manner. Now, he's playing with his ball again and is now going to pass it to this other fellow, who takes it and runs away with it. What they're waiting to see is which character the baby will prefer. But how will they know? Now, as an adult seeing this, the person who gave back the ball is good, is fine. The person who ran away with a ball is kind of a jerk. For now, you just say, "Well, who's the good guy, who's the bad guy?" You can't do that for a young baby. So, what you do is you hold them out and you get the baby to choose. The experimenter who hands the two puppets to the baby, she doesn't know which puppet was the good one and which puppet was the bad one, so she can't unconsciously influence the baby's preference. Hi. Hi, do you remember these guys from the show? Look at this, look at me. Which one would you like? Okay [inaudible]. Which one would you like? [inaudible]. That one? Good job. Okay, that was the nice one. Aswit has chosen the good puppet. The fact is that about 70 percent of babies do. Paul believe that this is a sign that these babies are drawn towards kindness and that this is a glimmer of a moral feeling.