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 sam scene ,but each perceivers (知觉)something different about it . Perceiving goes on in our minds .Of the three people who look out of the window,one may say that he sees a policeman giving a motorist a ticket .Another may say that he sees a rushhour traffic jam at the crossing.The third may tell you that he sees a woman trying to coss the street with four children.For perception is the mind*s explanation of what the senses in this case our eyes tell us . Many psychologists(心理学家)today are working to try do decide just how a person experiences or perceives the world around him .using a scientific method .There psychologists set up experiments in which they can control all of the factors (因素).By measuring and charting(制图表示)ther results of many experiments,they are trying to find out what makes different people perceive totallydifferent things about the same scene.