more general area of cognitive science and uses many concepts and models used in more general cognitive theories of learning. As such, cognitive theories view second-language acquisition as a special case of more general learning mechanisms in the brain. This puts them in direct contrast with linguistic theories, which posit that language acquisition uses a unique process different from other types of learning. The dominant model in cognitive approaches to second-language acquisition, and indeed in all second-language acquisition research, is the computational model. The computational model involves three stages. In the first stage, learners retain certain features of the language input in short-term memory. (This retained input is known as intake.) Then, learners convert some of this intake into second-language knowledge, which is stored in long-term memory. Finally, learners use this second-language knowledge to produce spoken output. Cognitive theories attempt to codify both the nature of the mental representations of intake and language knowledge and the mental processes that underlie these stages. In the early days of second-language acquisition research on interlanguage was seen as the basic representation of second-language knowledge; however, more recent research has taken several different approaches in characterizing the mental representation of language knowledge. Some theories hypothesize that learner language is inherently variable, and there is the functionalist perspective that sees the acquisition of language as intimately tied to the function it provides. Some researchers make the distinction between implicit and explicit language knowledge, and some between declarative and procedural language knowledge. There have also been approaches that argue for a dual-mode system in which some language knowledge is stored as rules and other language knowledge as items. The mental processes that underlie second-language acquisition can be broken down into micro-processes and macro-processes. Micro-processes include attention; working memory; integration and restructuring. Restructuring is the process by which learners change their interlanguage systems; and monitoring is the conscious attending of learners to their own language output. Macro-processes include the distinction between intentional learning and incidental learning; and also the distinction between explicit and implicit learning. Some of the notable cognitive theories of second-language acquisition include the nativization model, the multidimensional model and processability theory, emergentist models, the competition model, and skill-acquisition theories. Other cognitive approaches have looked at learners' speech production, particularly learners' speech planning and communication strategies. Speech planning can affect learners' spoken output, and research in this area has focused on how planning affects three