【正文】 or images, but to keep meaning. For example, try to remember a conversation you had yesterday with a friend. Now if you39。re like most people, you can39。t remember the exact words that you or your friend said, but you can remember the ideas that you discussed. Your memories of the points that were most important to you will be the clearest. So the essential feature of longterm memory is that it specializes in holding meaning. OK, are there any questions about that? Yes?STUDENT 1: Yeah. Can you explain why we don39。t remember all of the details of our past conversations?TEACHER: So the question is, Why do we forget? Well, most experts believe that if we remembered all of the details of our past experiences, our memory system would be filled with a lot of trivial information, a lot of trivial and generally useless information. Secondly, it is conceivable that we would find it extremely difficult to sift through such a . .. a mass of detailed information and find the really important information that we need. Um ... in other words, memory searches would proceed a lot more slowly.Student 1: OK, I see. Thank you.TEACHER: OK, let39。s move on to ways of measuring memory. Just as we distinguished three types of memory, there are three main ways of measuring how much a person remembers. The first of these methods is called recall. You use recall many times every day. Here39。s what I mean. . . . Take out a sheet of paper. . . . OK, now look at the word list in your text: drum, band, studio, and so on. . . . Read it silently to yourself. . . . OK? . . . Have you looked at all of the words? . . . OK, you should be finished by now. Now, close your book. Write down the words you saw, as many as you can, on your paper. . .. Go ahead.. .. OK, that39。s a simple recall test. Now, most of you probably remembered most of the words, but not all of them. Our memories, of course, are not perfect, and of course forgetting is natural.The second method of measuring memory is recognition. OK, for this you need another piece of paper, or just turn that one over. . . . All right. Number the page from one to eight. . . . Now look at the word list again. OK, now close your book. I39。m going to say eight words. You have to write yes or no—yes if the word I say was on the list, no if the word I say was not on the list. Ready? Here I go. 1. studio. 2. guitar. 3. stage. 4. recorder. 5. wiring. 6. song 7. vocalist. 8. drum. . . . OK, everybody finished? The answers are 1. yes, 2. no, 3. yes, 4. no, 5. yes, 6. no, 7. yes, and 8. yes. . . . How did you do? Anyone get all eight correct? . . . Good! That39。s what we call a recognition test. In contrast to the recall test, recognition is more receptive and doesn39。t require you to produce anything. For this reason,recognition is a lot easier for most of us than recall. In other words, asking yourself Have I seen this before? is easier than remembering everything you saw.Now the third basic method used to measure memory is relearning. Let me give you an example of a relearning test. First, you try to memorize a list of words. Then you don39。t look at the list for a period of time, maybe a week. If you39。re like most people, you won39。t be able to remember all of the words. After a week, you then look at the list a second time and try to relearn it. As you would guess, most people relearn information somewhat faster than they learn it the first time. By measuring the time people need to relearn information, we can calculate how much information they have stored in their longterm memories the first time.So, let39。s stop there for today. Uh ... I hope that you39。ll put today39。s material in your longterm memory ... or you39。re going to have a hard time with the test. See you next week.Unit 4 Actions Speak Louder than WordsTEACHER: OK, class, OK . . . let39。s begin. What do we mean when we say that actions speak louder than words?STUDENT 1: Uh . . . that means we believe people39。s actions more than we believe their words.TEACHER: Yes, exactly right—and, uh, in a sense, actions are more important than words. That39。s because we usually judge speakers39。 intentions by the nonverbal signals they send us. And that39。s what our subject today39。s all about, nonverbal munication—how we municate through our actions— facial expressions, eye contact, tone of voice, uh, body movement, and so on. And if any of you doubt the importance of these things, you might like to consider a couple of statistics I39。ve got here in front of me. Some munication specialists estimate we spend about 75 percent of our waking hours municating. And, more to the point, words account for only, mm, 10 to 30 percent of that munication—the bulk39。s nonverbal. That39。s food for thought, uh?Now although people clearly understand its importance, nonverbal munication—I39。ll call it . for short—is actually a rather recent field of study and owes a lot to an American anthropologist named Raymond Birdwhistle— spelled BIRDWHISTLE. Easy name to remember, right? Birdwhistle began studying nonverbal munication in the 1950s and, um ... one of his main ideas was that the meaning of nonverbal behavior depended on the context in which it was used.... Uh, it depends on the context. So, he looked at the whole context of nonverbal behavior— how and, uh, where certain types of nonverbal behavior appeared—and not just one particular behavior in isolation. Facial expressions, for example—frowns, smiles, raised eyebrows, and, uh, so on—we all use these to convey many different meanings. But those meanings are largely determined by the situations we39。re in and the relationships that we have with the people we39。re municating with. So, the sameexpression can have different meanings, right? Take a smile, for example, what does it mean?... Uh, Mike?STUDENT 2: Uh .. . uh, agreement, I guess. I like you.TEACHER: OK. Yes, it could mean I like you, but it could also mean I39。m trying to make you feel fortable, or maybe, uh, I think you