A、They can distinguish a happy tune from a sad one. B、They love happy melodies more than sad ones. C、They fall asleep easily whi

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. 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 watched two videos shown side by side, each featuring a different researcher, one of whom they’d met once two years earlier. The children spent 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 averted 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. 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.
   Our final study is from 1980, but is 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 deserting the babies’ emotions.
Questions 19 to 21 are based on the recording you have just heard.
19. What are the three interesting studies about?
20. What does the second study find about nine-month-old babies?
21. What is the 1980 study about?