We've talked about how to get information into memory. Now, consider how we get information out of memory. How do you remember things? One answer is retrieval cues. So cues can bring things back. If I have to go to a doctor, if I have a doctors appointment and I forgot about it, and I walked by and I see some pills, that they remind me. You could be cute and by all sorts of things, there's no joke. A rabbi is talking to his friend priest and says, "No. I can't find my bicycle anywhere, I think somebody stole it, I think somebody from my congregation stole it." And the priest says, "I have a good idea. Why don't you give your sermon next week on the Ten Commandments and then when you get to thou shall not steal, people will hear you, they'll now feel bad, and then they'll tell you where your bicycle is?" So they meet the next little while later and the rabbi has his bicycle and the priest, "Ah, did you do my my trick? Did it work? " And the rabbi says, "Well, it sort of worked. I gave my sermon on the Ten Commandments and then, when I got to thou shall not commit adultery, I remembered where my bicycle was." So retrieval queues work. A second way, fact about remembering things, it's what's called the compatibility principle. It's also called context-dependent memories, mistake dependent memory. And the idea is, that maybe in part because of cues, you remember things better when you have to recover them in the same context in which you learnt them. And this was illustrated by a quite cool experiment, where they get people, I think, they're scuba divers to either learn new words on a boat or whether underwater. And then they test them on their knowledge of the words, when either on a boat or underwater and it turns out that there's the compatibility principle at work. If you learnt them on a boat, you remember them better on a boat. If you learnt them underwater, you remember them better underwater. And this applies not just to physical states but to psychological states, so if you learn something when you're depressed, it might come to mind easier when you're depressed. If you learnt something while you're a little bit drunk, it may come to mind easier when you're a little bit drunk. Finally, they're searching strategies. So in one study, they asked people to remember their high school classmates from many years ago or even 20 years ago and you could check, if they are right by checking that the yearbook, so you have some certain objective source to determine whether or not people are right or wrong. And when you forces people to remember, they don't come up with many names. But then you could ask them to search, like a physical search in different ways, you say, "Well, what classes were you in? What clubs? What teams? Remember any parties you went to? Where you neighbors with any of the kids in your school? Any of kids from different countries? What about meals? What about adventurers, arguments, romances?" And what you discover is, the more you work on it, the more you explore things from different ends, from different angles, the more you'll remember. It's as if memories leave tendrils and if you grab hold of one of the tendrils, you can trace your way back to the source. And you could try to do this yourself, in the last lecture you saw a picture of a man and a house and I showed it to you i think more than once. How much can you remember of it? And what I would suggest is, that if you try right away, you just list, "Oh, I remember this and that." And you give up, you're giving up too soon. If you can have explored different ways of thinking about a different possibilities, different things that could be in the picture, sooner or later, you'll know more and more. Memory, as we'll see it's not ever like a photograph or a video, it's never exact, it's always reconstructed. And sometimes when you do this sort of searching, you run the risk of creating false memories which we'll discuss very soon. But still, searching strategies can really help you recover memories that you had believed to be lost.