Why constructions are learned
The constructionist approach to language advocates the position that grammatical constructions are learned inductively on the basis of domain-general processes of categorization. However, it is clear that the categorizations must be constrained—generalizing purely on the basis of formal similarity, for example, would often lead to erroneous conclusions. We do not make all conceivable generalizations. Therefore, we need to account for the simple fact that generalizations at the level of constructions are made. As many have emphasized, human categorization is generally driven by some functional pressure, typically the need to predict or infer certain properties on the basis of perceived characteristics. In the case of language, the language learner’s goal is to understand and to be understood: to comprehend and produce language. There is ample functional pressure to predict meaning on the basis of given lexical items and grammatical characteristics (comprehension); conversely, there is pressure to predict the choice of lexical items and grammatical characteristics given the message to be conveyed (production). Since the sentences the child is learning to understand and produce form an open-ended set, it is not sufficient to simply memorize the sentences that have been heard. The child must necessarily generalize those patterns at least to some extent in order to understand and produce new utterances. Evidence is presented that indicate that constructions are at least as good predictors of “who did what to whom” as main verbs; their predictive value then, serves as a reason to learn them. A second motivation for representing generalized constructions is based on evidence that constructions are primed in production.