Does Dependency Locality Predict Non-canonical Word Order in Hindi?

TL;DR

This study investigates whether dependency length minimization influences non-canonical word order in Hindi, finding that discourse predictability and information status are more significant factors than dependency length alone.

Contribution

The paper introduces a classifier that assesses the influence of cognitive and discourse features on Hindi word order, highlighting the primacy of surprisal and givenness over dependency length.

Findings

Dependency length influences non-canonical order but is not the main predictor.

Surprisal and givenness are stronger determinants of word order preferences.

Human evaluations support the computational findings.

Abstract

Previous work has shown that isolated non-canonical sentences with Object-before-Subject (OSV) order are initially harder to process than their canonical counterparts with Subject-before-Object (SOV) order. Although this difficulty diminishes with appropriate discourse context, the underlying cognitive factors responsible for alleviating processing challenges in OSV sentences remain a question. In this work, we test the hypothesis that dependency length minimization is a significant predictor of non-canonical (OSV) syntactic choices, especially when controlling for information status such as givenness and surprisal measures. We extract sentences from the Hindi-Urdu Treebank corpus (HUTB) that contain clearly-defined subjects and objects, systematically permute the preverbal constituents of those sentences, and deploy a classifier to distinguish between original corpus sentences and artificially generated alternatives. The classifier leverages various discourse-based and cognitive features, including dependency length, surprisal, and information status, to inform its predictions. Our results suggest that, although there exists a preference for minimizing dependency length in non-canonical corpus sentences amidst the generated variants, this factor does not significantly contribute in identifying corpus sentences above and beyond surprisal and givenness measures. Notably, discourse predictability emerges as the primary determinant of constituent-order preferences. These findings are further supported by human evaluations involving 44 native Hindi speakers. Overall, this work sheds light on the role of expectation adaptation in word-ordering decisions. We conclude by situating our results within the theories of discourse production and information locality.