Question 20 is based on the recording you have just heard.

Recording Two

听力原文

    In last week’s lecture, we discussed the characteristics of the newly born offspring of several mammals. You probably remember that human infants are less developed physically than other mammals of the same age. (19) But in today’s lecture, we’ll look at three very interesting studies that hint at the surprising abilities of human babies.

    In the first study, three-year-olds watch two videos shown side by side, each featuring a different researcher, one of whom they’d met once, two years earlier. The children spend longer watching the video showing the researcher they hadn’t met. This is consistent with young children’s usual tendency to look longer at things that aren’t familiar. And really this is amazing! It suggests the children remembered the researcher they’d met just one time when they were only one-year-olds. Of course, as most of us forget memories from our first few years as we grow older, these early long-term memories will likely be lost in subsequent years.

    Our second study is about music. For this study researchers played music to babies through speakers located on either side of a human face. They waited until the babies got bored and inverted their gaze from the face. And then they changed the mood of the music—either from sad to happy, or the other way around. This mood switch made no difference to the three-month-olds, (20) but for the nine-month-olds, it was enough to renew their interest and they started looking again in the direction of the face. This suggests that babies of that age can tell the difference between a happy melody and a sad tune.

    (21) Our final study is from 1980, but it’s still relevant today. In fact, it’s one of the most famous pieces of research about infant emotion ever published. The study involved ordinary adults watching video clips of babies nine-months or younger. In the video clips, the babies made various facial expressions in response to real life events, including playful interactions and painful ones. The adult observers were able to reliably discern an assortment of emotions on the babies’ faces. These emotions included interest, joy, surprise, sadness, anger, disgust, contempt, and fear.

    Next week, we’ll be looking at this last study more closely. In fact, we will be viewing some of the video clips from that study. And together, see how well we do in discerning the babies’ emotions.

20. What does the second study find about nine-month-old babies?

解析：A。录音中提到，这个年龄段的婴儿可以分辨出快乐旋律和悲伤旋律的不同。再根据下文，这个年龄段指的是九个月大的婴儿，故A项正确，其他选项在录音中均没有提及，故排除。