As one of the most important perspectives to understand the world, metaphor interpretation has long been concerned by researchers in cognitive fields. The development of advanced neuroimaging technologies, such as fMRI and ERP, which facilitate observing the process of metaphor comprehension in the brain, have all the more pushed this research forward. However, the conflicting conclusions drawn by different researchers confuse our view about the brain areas involving metaphor processing. Currently, there are three prevailing views, namely, the right brain theory, the left brain theory and the whole brain theory, which arouse our reflection. We have found out that there is something in each conclusion while there do exist contradictions between these conclusions. The reasons for the contradictions lie in the following two aspects: (1) There are some drawbacks in the researchers' view that metaphor processing simply involves some particular area in the brain|(2) There are still some vulnerabilities in their experimental designs. It should be noted that metaphor comprehension, i.e. the input, extraction, processing and integration of metaphorical information, is a quite complicated process, which is affected by many factors, including the characteristics of metaphor, the difference of individual processing, the way of information integration in the brain, and so on. That is why we cannot take it for granted that we have seen the whole picture of metaphor processing in the brain while we have only found out some of the aspects of the processing. Metaphor comprehension is such a complicated process that it cannot be completed by a single brain area. As an external stimulus, the novelty, visualization and multi-modality of metaphor itself may have influence on the processing. And the difference between individuals, including their intelligence and their familiarity with a given metaphor may also have effect on the processing. Besides, the way our brain integrates the metaphor information likewise presents the versatility and complexity of metaphor processing from input, extraction, processing and integration.
Based on the experimental results of the previous researchers, it is concluded in the paper that the brain processing of metaphorical language has its own special features but it also shares the common features of general language processing. As far as a normal individual is concerned, the classical brain areas of language processing are situated in the left hemisphere but the right hemisphere will be involved in the processing of metaphorical language. The involvement of the right hemisphere in the metaphor processing is determined by the novelty and visuality of a metaphor, that is, the more novel and more visual a metaphor is, the more probably the right brain participates in the processing. On the contrary, the more conventionalized a metaphor is, the less involved the right brain is. The familiarity with metaphor is the norm for the individual to identify whether it is a novel or a conventional metaphor being processed in the brain. To the individual, the more unfamiliar he/she is with the metaphor, the more novel it is. On the contrary, the more familiar he/she is with the metaphor, the more conventional it is. However, to those groups of people as young children whose brains are under development, old people whose brains are degenerated, or patients whose brain is injured, it is more difficult for them to understand a metaphor and then it is most likely for them to consume more cognitive resources, which leads to a larger scale of activation. The multi-model input of metaphor and the way of information integration in the brain also determine that the metaphor processing cannot be completed by a single brain area. Instead, it should be done from the input of metaphorical information through different sensory channels, to the extraction and processing by corresponding functional brain areas, and then to the integration in the whole brain network. Therefore, metaphor comprehension is such a complicated process that it involves the cooperation of the related brain areas, including the processing of corresponding functional brain areas and the blending of related brain areas in the neural network. Although some brain area or areas takes a more active role in a certain cognitive task, the processing still needs the cooperation with other areas involved in the whole brain network to guarantee the prompt and correct processing of metaphorical information.