I want to end with what I think is the most surprising and perhaps controversial aspect of the study of memory. Which is how we often get things wrong, and how our memories can be distorted and shaped by factors we're unaware o. And how we're often very confident about memories, about things that didn't really happen. And there's many ways in which we can get false memories. One is simply expectations. Our beliefs about what should happen, what typically happen will shape our memories of what happens. People have done studies where they tell people stories for instance about somebody who goes to a dentist office or goes has a meal in a restaurant. And then later asked them what they remember of the story. And what you often find is that they tend to fill in the details that typically occur even though they didn't. So the story might not mention paying the bill. But somebody later will confidently remember that they've been told a person paid the bill because they put in that fact. Studies of eye witness testimony, and here the great work of a psychologist Elizabeth Loftus plays a role. Have found that leading questions will shape how you remember a scene. So for instance, if you ask people questions like did you see the broken headlight versus did you see a broken headlight? Later on, they're more likely to remember that there was a broken headlight if they heard did you see the broken headlight? Because presupposes a broken headlight, so they stick it into their memory. If you ask them questions like, did you see the children getting into school bus? Later on just asking that question makes them much more likely to remember school bus in the film. Or given a scene where they're asked, how fast were the cars going when they hit each other, versus how fast were the cars going when they smashed into each other? [NOISE] A week later when asked, did you see broken glass? They're more likely to say yes if they were given the word smashed because their questions after the event shape their memory of the event. Another domain where false memories apply concerns hypnosis. So there's some people who try to do what's called hypnotic regression. Where you get people to a hypnotic state and ask them to go back and remember something from their past. A license plates seen at the crime scene or their sixth birthday, and what happens here is there's no magic. It's not as if where the mind is a video recorder and we're scanning back to get to the truth as you might seen in some movies. Instead, what really happens is people really try hard to remember, but if they can't, they'll make it up. What hypnosis does is make people cooperative. And the cooperation will often manifest itself into creating and making up memories that seem true in order to satisfy the questioners. There's been a lot of debate about repressed memories, where some people have argued that adults do report memories of traumatic childhood abuse, often sexual abuse. And these are said to be accurate, repressed, which means there was a long period where the person just forgot about them. And elicited through work with a therapist often using hypnosis. And actually just to add repressed is more than just forgetting, it is that if something is sufficiently unpleasant, you might wipe it from memory at least temporarily or you might suppress it, repress it. Now there's a lot of debate about that. There's a lot of debate over whether such a thing really exists. Whether there's such a thing as a physiological mechanism to block your access to a memory that's sufficiently horrible. Also, regardless of what you think about that and I think most psychologists are very skeptical about repression. It is pretty clear that you can create false memories, even false memories of dramatic and traumatic events through discussion, through exercises where you think back, where you try to reconstruct things. Often through interaction with a therapist where a therapist is perfectly well-meaning. And believes that he or she is sort of recovering a memory from the past, but in reality is creating one. Finally, there are flashbulb memories. Depending on your age, you might well remember, if you're American or actually from anywhere, where you were on September 11, 2001. And many people it was a very dramatic event, a terrorist attack in New York. And people often have these very vivid, very powerful memories, but it turns out these memories are actually not particularly accurate. In fact, memories of significant scenes are more vulnerable to distortions because you talk about them. You talk about them with other people, you recount the story. And what happens over time is, you no longer remember what really happened rather, you remember the story. So, to bring this to a close, in our previous couple of lectures, we've talked about perception attention memory, and we've talked about a lot. But I just want to hit the main points, which is perception is hard. And succeeding at perception involves educated and unconscious guesses about the world. For attention we attend to some things and not others which you already know, or maybe you didn't know is you miss a surprising amount of what happens in the world. And finally, I think there are three main morals of this memory lecture. There are many types of memory, the key to memory is organization and understanding, and finally, you can't trust some of your memories.