The way we see things is more complicated (复杂的) than we imagine. Our eyes give us information all the time. But our brains decide what is (11) to us. For example, if you (12) a crowded street, you will see many faces. But you will probably not really notice them. But if you see someone you know, you will (13) him immediately. From this example we can see that your brain chooses the visual information which is (14) to you, and rejects the information which it does not need. The way your brain explains that information depends on the knowledge you have about the world. And all this happens in (15) a second.