单选题 .  Ask three people to look out of the same window at a busy street corner and tell you what they see. Chances are you will receive three different answers. Each person sees the same     21    , but each perceives     22    different about it.
    Perceiving goes     23    in our minds.     24    the three people who look out of the window,     25    may say that he sees a policeman giving a motorist a     26    . Another may say that he sees a     27    traffic jam at the     28    . The third may tell you that he sees a woman trying to     29    the street with four children     30    tow. For perception is the     31    interpretation of what the     32    —in this case our eyes—tell us.
    Many psychologists today are working to try to     33    just how a person     34    or perceives the world around him. Using a scientific     35    these psychologists     36    experiments in which they can control all of the     37    . By measuring and charting the     38    of many experiments, they are trying to     39    what makes different people perceive totally different things     40    the same scene.21.