Subtitles section Play video Print subtitles The following content is provided under a Creative Commons license. Your support will help MIT OpenCourseWare continue to offer high quality educational resources for free. To make a donation or view additional materials from hundreds of MIT courses, visit MIT OpenCourseWare at ocw.mit.edu. PROFESSOR: Good afternoon. Congratulations for braving it through what's now become a weekly snow disaster. This week's maybe three of them or something. My name's John Gabrieli. This is Introductory to Psychology, 9.00. This is a course about you. The entire course is what do we understand in a scientific way about human nature-- how people's minds work, how people's brains work that supports their mind. This entire course is about what's a scientific way to understanding how people feel, think, and act in the world. And so we're trying to say that we constantly think you must in your everyday life think about why do you have your preferences, your desires? What's easy for you? What's hard for you? What's delightful for you? Why do other people behave the way they do? How do they think? How do they feel? And so there's a lot of realms of this that are tough to get to by science. But what we're going to focus on this semester is where the scientific approach has shed light in the way that we used to think about experiments and evidence, about how humans tick. And as we go through this semester, we'll talk about the brain, we'll talk a fair bit about chapters from this book, The Man Who Mistook His Wife for a Hat, from Oliver Sacks. It was a bestseller even when it wasn't [? a ScienceWare ?] course. It's a great book. You'll enjoy it. Short, really fun chapters. We'll talk about how we perceive the world; how we see; especially, a little bit, how we hear; how we think; how we feel; personality; how we differ from one to the other; and what we're sort of like; and how we behave in the world; development from childhood and infancy through adolescence, through young adulthood, where you are mostly, through getting older, where I am; social interaction, how we behave in groups and think about other people; and variation in the mental health or psychopathology. And increasingly, we understand that there's a huge number of people who, at some moment in their life or another, struggle with some aspect of mental health. And then we'll focus a lot on, not only the psychological aspects of what we study in terms of behavior, but also the brain basis of that, and think a little bit about to what extent the mind is what the brain does, to what extent the mind is what the brain does. And so for every dimension of being a human being that we'll talk about, we'll also talk about what we understand currently from the neurological and neuroscientific literature about how the human brain supports and contributes to different aspects of being a person. OK. So everybody who works in a certain field thinks that their field is really, really, really special, right? So here's why psychology is really, really, really special. So it's really, really special, I think, most of all, because every endeavor that we undertake at a university or in society as a whole-- it's about people, right, except for when we think about the rest of nature. But people study biology, chemistry, and physics. And they think, right, that the sun orbits the earth for some period of time. And then they think it's the other way around currently, right? OK, so people come up with these conclusions. Even though we're trying to understand nature, it's people who make certain investments in economics or behave in a certain way or vote in a certain way. It's people who make music and appreciate music, make art and appreciate art, read and write literature, right? So in all these dimensions, there's something very fundamental about what it is about the human mind that gives birth to these areas of inquiry and how those areas, domains of human experience, are enacted. So my only goal today is to try to convince you in a number of different ways that we're not simple video camera in our minds between our ears, recording the world in some objective, simple way, that even the simplest, most obvious things are interpretations of the world around us at many different levels of thought and feeling and perception. And then our minds, the way our minds are constructed, determines the world that we experience, that we see, that we act upon. And even very simple things that we think are pretty objective and simple, right in front of our eyes, are determined by inferences and deductions that our mind makes, weighing sources of evidence in the world and coming to conclusions about what's around us, what we hear, what we see, and how we think. So let's start with seeing. If your vision is reasonable, we say we see something, we believe it, right? So let's start with something very simple-- these lines. So one of the tough things about psychology is ever since the Internet came into existence, people know every cool thing there is to know, right? OK. I can tell you when I began teaching, people said, oh my gosh, I've never seen such a thing. It's unbelievable! And then now, it's like two thirds of the class is like, yeah, I've got that on my computer at home. We did that in third grade or whatever. So all I'm saying is enjoy the ones you haven't seen before, don't ruin it for your neighbors today, because it's harder and harder to surprise the world in a nice way, right? OK, but let's look at these lines for a moment here. And perhaps you'll have the sense, and maybe-- is it glaring up there, sir? Let's see. OK, is that better? OK. Maybe not. So you might have the sense that this line is a different length than this line. And this might be somewhere intermediate, right? Now you know, because of psychology, it's all a trick. But what's simpler than the length of a line? What's more objective in some sense than the length of a line? But if we look at the actual lengths, they're all literally identical. But that center part looks different. So what does it mean for it to look different? It means our minds are determining as simple a thing as how long a line is depending on the other information surrounding it. It's an interpretation in context. If we're simply looking, the lines will look the same. Let's try another one. It's remarkable that those two lines are identical in length. [LAUGHTER] PROFESSOR: OK, all right. It's OK to test the limits of the credibility of the audience, right? All right. Yeah. Of course, if our visual system were ludicrously off, we'd be constantly walking into walls and falling out windows and things like that, right, if we were misestimating at that length. So the idea where we have visual illusions-- and I'll show you some more that I think you'll be impressed by-- it's not that our visual system is messed up or that psychologists think it's hilarious to trick us. It's that lots of things our visual system is a brilliant at, but it's brilliant by having certain laws or principles that it follows. And we can show this following those principles by seeing that when we mess with the typical circumstances, those principles calculate the wrong answer. So here's another one. So, to most people, which line looks bigger, the one in the middle or the one on the side? I know you know it's all a trick, right? OK. What could be more obvious than that this is longer? It's just a simple line, but if we draw red lines on top of it then move them over here, they're dead identical. The central circle-- does one of them, the middle circle, look larger than the other? Now you already know, intellectually, that it will turn out those two circles in the middle will be the same. But you have to convince yourself that it still looks like they're different. Here there in red. Here they are next to each other. They're identical. Again, this is evidence that, even for a simple thing like the size of a circle, your mind is making inferences. And there are principles and laws that it's following that determine what it is you think that you see. Here is two monsters chasing each other. But in fact, they're identical in size. The perspective cues make the more distant one look much bigger. This is from Ted Adelson. This is a beautiful demonstration of an illusion. Ted Adelson's in the psychology department. There's a letter A here. And believe it or not, there's a letter B there. Let's see if this looks any better when it goes like this. It doesn't. All right. So one of the important things about illusions, demonstrations in this class-- and you will learn this as we go along-- is occasionally they fail, and we come back and discover what the lesson of that is. So I'm just telling you it's showing you on my monitor much brighter. It always has before. We'll adjust that. So I'm going to skip this, but I'll show you another time, because it's so good. And I'm going to feel bad about this. OK. Now, let's see. This'll work. All the same shade of grey, right? [LAUGHTER] PROFESSOR: Did that work reasonably from where you sat? We'll try a few more. Maybe. For some reason, my connection's always like this, sorry. Does that one look lighter than that one that way? Yeah. Now they look radically different, right? It's the same grey constantly. But again, the context is hugely determining how to bright you see that grey. There it is. Two boxes equal grey. So things as simple as how bright something is or how long something is depend on interpretation. Here's an illusion from Roger Shepard. It's kind of great. So here's two kind of different looking tables, right? But they're not that different. And watch. There goes one tabletop. You're not impressed that those are identical tables? OK. Want me to do it again? That's the identical tabletop. To me, the one on the left looks pretty rectangular and the one on the right looks pretty square-ish. You're not easy to impress, are you? [LAUGHTER] PROFESSOR: You see that those two bars are moving together at the same time. Does it look like they're little steps? It'll show you. All right, fine. It's just like that, but now you add those bars. Does it look like little steps?