A discourse account of intervention phenomena: An investigation of interrogatives

Sentences where like-moves-over-like, e.g. this is the cat that the dog was chasing <the cat>, have occupied language researchers over the past two decades. They are often described as “intervention” sentences as one element intervenes in the movement of another. Such structures are difficult to comprehend by children or adults, and this effect is exacerbated in language-impaired individuals. Dominant theories, e.g. Rizzi’s Relativised Minimality (RM), propose that the two NPs interfere with each other by virtue of having overlapping features. However, such sentences are also rarely encountered due to discourse constraints. For example, subject NPs (the dog) tend to be pronominal as they are typically aligned with topic-hood. This paper investigates whether discourse can account for intervention in questions. It employs a mixed methodology. Firstly, corpora were investigated to assess the degree to which discourse impacts on input frequency. Secondly, a behavioural study was conducted to unpack the relationship between frequency and processing in children. It was found that the input frequencies of intervention structures are predominantly influenced by discourse, and that intervention structures are vanishingly rare in the input. However, a link between frequency and processing was not observed, with the findings more supportive of RM. It is suggested that a consideration of discourse as an external phenomenon may yield new insights into intervention structures.