Discourse can often be unclear or ambiguous in which case participants are required to negotiate what meaning they are conveying e.g. a warning or a threat. This process, that is, the negotiation of meaning, is the subject of my last section. Problems of communication affect us all in many aspects of day-to-day living, and can cause serious trouble. It is incredibly easy to be unintentionally misunderstood, or to speak ambiguously or vaguely. To make communication successful is difficult. An excellent example of difficult communication is the doctor-patient relationships, where most patients fin it difficult to describe their symptoms, whereas for doctors the problem is to formulate a diagnosis in words which the patient will understand. Within this interaction, there is a need and a wish for mutual understanding.
When communicating, speakers often experience considerable difficulty when their resources in their foreign or native language are limited. A major feature of conversation involving L2 learners is that the learner and native speaker together strive to overcome the communicating difficulties which are always likely to arise as a result of the learner’s limited L2 resources. This has become known as the negotiation of meaning. On the part of the native speaker, this involves the use of strategies and tactics. Strategies are conversational devices used to avoid trouble; examples are relinquishing topic control, selecting salient topics, and checking comprehension. Tactics are devices for repairing trouble; examples are topic switching and requests for clarification. Other devices such as using a slow pace, repeating utterances, or stressing key words can serve as both tactics and strategies. The learner also needs to contribute to the negotiation of meaning, however, and he can do so by giving clear signals when he has or not understood and, most important, by refusing to give up. The result of the negotiation of meaning is that particular types of input and interaction result. In particular, it has been hypothesized that negotiation makes input comprehensible and in this way promotes L2 acquisition.