Boston, M.F., Hale, J., Kliegl, R., Patil, U., Vasishth, S. (2008). Parsing costs as predictors of reading difficulty: An evaluation using the Potsdam Sentence Corpus. Journal of Eye Movement Research, 2(1), 1-12.

Boston, M.; Hale, J.; Kliegl, R.; Patil, U.; Vasishth. S.

2008

Boston, M.F., Hale, J., Kliegl, R., Patil, U., Vasishth, S. (2008). Parsing costs as predictors of reading difficulty: An evaluation using the Potsdam Sentence Corpus. Journal of Eye Movement Research, 2(1), 1-12.

The surprisal of a word on a probabilistic grammar constitutes a promising complexity metric for human sentence comprehension difficulty. Using two different grammar types, surprisal is shown to have an effect on fixation durations and regression probabilities in a sample of German readers’ eye movements, the Potsdam Sentence Corpus. A linear mixed-effects model was used to quantify the effect of surprisal while taking into account unigram frequency and bigram frequency (transitional probability), word length and empirically-derived predictability itself. This work thus demonstrates the importance of including parsing costs as a predictor of comprehension difficulty in models of reading, and suggests that a simple identification of syntactic parsing costs with early measures and late measures with durations of post-syntactic events may be difficult to up-hold.

The work presented in this paper showed that surprisal values calculated with a dependency grammar as well as with a phrase-structure grammar are significant predictors of reading times and regressions. The role of these surprisals as predictors was still significant even when empirical word predictability, n-gram frequency and word length were also taken into account. On the other hand, surprisal did not appear to have a significant effect on empirical predictability as computed in eye-movement research.

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