The language that learners hear and read serves as input to their language development. The cognitive processes that allow them to learn from the input are not 'shut clown' when they are interacting with other learners. Thus, when learners interact with each other, they may provide some incorrect input. Furthermore, when learners come from the same first language background and are at roughly the same level of proficiency, they are likely to understand each other very well, eliminating the need for negotiation far meaning that might lead them to replace their interlanguage patterns with more target like ones. Nevertheless, the benefits of pair and group work far outweigh the disadvantages, especially if the tasks are properly designed.