【正文】 information processing: the bottom up processing and topdown processing. However, neither of them alone could ensure an efficient reading. Generally, learners are encouraged to use them interactively in their reading. Bottomup modelThis way of reading reflects the belief that reading prehension is based on the understanding and mastery of all the new words, new phrases, and new structures. Therefore, readers in this way would concern new vocabulary and new structures first and then go over the text sentence by sentence. The reader builds up a meaning from recognizing letters and words, working out sentence structure. If our word knowledge is inadequate, or if the writer’s point of view is very different from our own, perhaps, we cannot believe that apparent message is really just what the writer intended. Besides, when we read something which does not contain any new words, but sometimes we still find it difficult to understand its meaning. For example, the sentence “It is a piece of cake” contains simple words, if we just decode every word, we don’t know it describes the things which are easy. Topdown modelA different view believes that our background knowledge plays a more important role than new words and new structures in reading prehension. This approach occurs when readers use prior knowledge to make predictions about the data they will find in a text. This is why we can understand an article with some new words or new structures in it, because we can guess the meaning of the article based on our knowledge about the topic without too much difficulty. A classic topdown theory is Goadman’s view of reading as a psycholinguistic guessing game. He claims that we draw on our own experience, knowledge and prediction we can make, based on the schemata we have acquired to understand the text. For example, “He is so lucky that he passed the exam. He is really a lucky dog”. Although we don’t know what lucky dog really is, we can guess according to the former sentence and meaning. Therefore, we can guess the lucky dog means a person who is very lucky, which is based on our own knowledge. However, the sole dependence on Topdown model can make the readers misunderstand and make ridiculous guessing. They may confused by the relationship of the “l(fā)ucky dog” and “him” The interaction of topdown and bottomup processingThe disputes between the topdown and bottomup models have to be solved. Now it has generally been accepted that the reading process is interactive, so we adopt the topdown model to predict the probable meaning, and then move to the bottomup model to check whether it is really what the writer says. This has been known as interactive reading. It is presented by Dechant (1991) that the reader constructs meaning by the selective use of information from all sources of meaning (Phonemic, syntax, semantics) without adherence to any one set order. The brain receives visual information and at the same time, interprets or reconstructs the meaning of the text. Therefore reading is involved not only the printed words but also the reader’s knowledge of the language and of the world or of the text types. Learners are encouraged to decord and understand words, phases and sentences in the text. At the same time, we use expectation, previous knowledge to understand the reading text. Background knowledge that aids in text prehension has recently been studied with the help of schema theory, and the research shows that the interactive model pensates the limitations presented by bottomup model and topdown model.3. Factors affecting reading VocabularyAs the basic element of language, vocabulary is the backbone of the whole language system. One of the reading processes is to decode and understand words. If we know the precise words chosen by the writer, most of the time, we can understand what he said. If we have larger amount of vocabulary, it would be easier for us to understand a text. However, new words affect the speed as well as the prehension. There are some main points about vocabulary. One is that the same word in different context has different meanings. Besides, to enlarge vocabulary, we should know the word building such as stems and affixes. What is more, the words certainly reflect the difference of culture. Vocabulary is one of the chief factors affecting reading. The ability to distinguish the meaning of words in different context is one of the most important aspects of successful reading. Cultural backgroundPhillips (1984) pointed out: a successful reading of any passage depends on a bination of linguistic knowledge and background knowledge. It is cognitive skill and general experience and knowledge of the world, whether acquired by experience or by learning that influence greatly the reading prehension process, because the more the reader brings to the text, the more is taken away. Indeed, in the reading process, the linguistic knowledge, like vocabulary, is very important, but sometimes we can’t read between the lines without the help of background knowledge of culture, because the meaning of words are acquired in a certain circumstance of culture. For example, even though you know every word in one sentence, however, if you don’t know the very English culture, such as histories, customs, religions, you may fail to understand the exact meaning of the texts. We can say that background knowledge is as important as any other factors affecting reading.Lacking of the necessary cultural background may hinder people from prehending language. For instance, when the president Reagan took up his post, an American told a Chinese: “The United States has gone from peanuts to popcorn.” The structure of this sentence is very simple. However, the Chinese didn’t understand the sentence at that time until his friend explained to her that is about background knowledge. Because former president Jimmy Carter owned a big peanut farm while the present president Reagan is an