Input Processing Theory

Input processing theory, put forward by the linguist Bill VanPatten in 1993, describes the strategies and mechanisms that language learners use to connect linguistic form with its meaning or function. It is a theory within second-language acquisition that focuses on how learners process linguistic data as they encounter it in spoken or written input. The theory rests on two principal sets of sub-principles: a primacy-of-meaning group, covering how learners prioritize content words and meaningful cues under limited attentional resources, and a first-noun group, covering how learners use lexical semantics, the relative probability of events, and surrounding context to assign grammatical roles such as subject and object. Critics have challenged the theory's claim that comprehension drives acquisition, have questioned how cleanly input can be separated from intake, and some argue the model pays too little attention to learner output.