【答案解析】Subliminal perception is the perception without realizing the existence of a stimulus. The professor uses one experiment to illustrate the effects of this psychological phenomenon. Two groups of volunteers were shown a different picture and the pictures were moving so quickly that nobody could catch the contents. The first group was shown a picture of an angry boy throwing away a piece of cake and the second group was presented a picture of the same boy eating the cake happily. Then both groups were shown slowly and clearly a picture of a boy with no emotion and movements. When these two groups were asked to describe the picture, most of the first group described the boy as angry while the majority of the second group depicted him as a lively boy. [听力原文] M: Here we go. Subliminal perception is the perception without realizing the existence of a stimulus. Sounds appealing, right? In other words, it is like we feel what we don't see. However, the effects of subliminal perception on people are even more interesting to observe. Here is an experiment to demonstrate the effects of subliminal perception on people. Two groups of volunteers participated in the test. Both groups were shown a different picture at first. The picture for the first group described an angry boy who was throwing away a piece of cake. However, the picture shown to the second group portrayed the same boy who was eating a piece of cake happily. The pictures were moving so quickly that neither group had enough time to catch the contents. That is to say, the volunteers had no idea of what they saw on the pictures. Then, another picture was presented slowly and clearly to both groups. In this picture, the boy showed completely no emotion and no movement. Finally, the participants of both groups were required to describe the potential character of the boy in the third picture to researchers. There came the funny part. Most people in the first group tended to comment on the boy's character as negative, while the majority in the second group depicted the boy as someone with a positive character.