The Effects of Word Predictability and Contextual Uncertainty in the Processing of Korean Dative Sentences: An Eye-Movement Rea

Year
2018
Volume 18
Issue 2
Pages
127-152
Authors
Hongoak Yun,Dongsu Lee,&Upyong Hong
Abstract
The purpose of this study was to investigate the conjoined roles of word predictability and contextual uncertainty in modeling readers’ processing difficulty in the integration of recipients or patients into Korean dative sentences, by observing readers’ eye movements in reading. The recipients and patients were arranged in a canonical order (i.e., recipient before patient) or a non-canonical order (i.e., patient before recipient). Using a cloze task, we measured a word’s conditional probability to estimate the degree of predictability for a target word given a context. The outputs from the cloze- type listing task were used to compute entropy-based contextual uncertainty corresponding to the degree of contextual constraint at the point in which target words would appear. While the effect of word predictability on eye movement in reading was being taken into account in linear mixed-effect models, the significant effect of contextual uncertainty emerged only in the processing of target words in non-canonical sentences in a way that words were read more rapidly as the strength of contextual uncertainty increased. Including the contextual-uncertainty factor in the model of word predictability improved the goodness of the model fit significantly in the condition of canonical sentences and marginally significantly in that of non-canonical sentences. Our results suggest that the role of contextual uncertainty is important to improve the model performance accounting for expectation-based probabilistic readers' behaviors during sentence comprehension. A weak context (i.e., high contextual uncertainty) in which a wide distribution of possible choices is constructed contributes to the reduction of processing difficulty, in particular, when readers do not make a strong commitment for upcoming structural information.

Keywords: expectation, predictability, uncertainty, entropy, sentence comprehension, eye-movement in reading