Global estimates of syntactic alignment in adult and child utterances during interaction: NLP estimates based on multiple corpora

The study of how conversational partners align language behavior has been given much attention in psychology, linguistics and sociology. Prominent frameworks for investigating this type of cooperative behavior include dialogic resonance, the interactive alignment model, abstract structural priming, and format tying. Yet, we do not have estimates of the overall amount of discourse alignment in human conversation. Obtaining estimates is challenging because alignment is complex, occurring at many different levels, and the resources needed to manually annotate large corpora to measure all aspects of discourse alignment restrict rapid progress on the issue. However, recent NLP research has developed systems to estimate alignment at least at the lexical and syntactic levels of conversation. While such systems come with error rates and lack the precision of manual annotation, interesting findings are emerging such as a recent study reporting grammatical alignment levels in the British National Corpus (BNC) was not particularly high, possibly what would be expected by chance. This is a controversial paper. The current study therefore, replicates the study in the recently released BNC 2014 spoken, finding in this corpus syntactic similarity is also close to the alignment one would get by randomly pairing conversational turns. The study goes further, finding the most frequent similarity level between utterances is zero, and that there exist no convincing cases of abstract structural alignment. Extending the research to child language corpora, grammatical alignment between children and adults is slightly above chance, though the most frequent level of syntactic similarity is zero, with no convincing cases of an abstract structure used by a child because their adult interlocutor had primed them. The findings might mediate theory-building that assumes discourse alignment at the grammatical level is widespread throughout conversation between adults or adults and children.