Paper: Complexity Metrics in an Incremental Right-Corner Parser

ACL ID P10-1121
Title Complexity Metrics in an Incremental Right-Corner Parser
Venue Annual Meeting of the Association of Computational Linguistics
Session Main Conference
Year 2010

Hierarchical HMM (HHMM) parsers make promising cognitive models: while they use a bounded model of working memory and pursue incremental hypothe- ses in parallel, they still achieve parsing accuracies competitive with chart-based techniques. This paper aims to validate that a right-corner HHMM parser is also able to produce complexity metrics, which quantify a reader’s incremental difficulty in understanding a sentence. Besides defining standard metrics in the HHMM framework, a new metric, embedding difference, is also proposed, which tests the hypothesis that HHMM store elements represents syntactic working memory. Results show that HHMM surprisal outperforms all other evaluated metrics in predicting reading times, and that embedding difference makes a significant, independent contribut...