Expectation-based sentence comprehension in Korean: evidence from behavioral and neurological studies

The goal of this study was to provide meaningful insights in the algorithms of statistical and computational modeling in natural language processing, by emphasizing the role of expectation in human language comprehension. To obtain the evidence for expectation-based sentence comprehension in Korean, we revisited Lee's study [1, 2] in which the processing of Korean relative-clause sentences was tested. In Study 1, using Lee's materials, we conducted gated cloze tasks by which the conditional probability of a target constituent was computed at each point in a way that a word was incrementally added to a sentence fragment. Then, the patterns of the computed conditional probabilities of target constituents were compared to those of the reading times of target constituents that Lee had observed. In Study 2, we examined whether the patterns of the expectation-based sentence processing that we observed in Study 1 was modulated by readers' working memory capacity. Finally, in Study 3, an fMRI study was conducted to explore the locus of expectation-based sentence processing in brain. We found that the patterns of conditional probabilities were mapped to those of behavioral reading times, but we did not observe individual differences in expectation-based comprehension. We also obtained neurological results suggesting that the Broca area is the locus for the processing of the expected syntactic information. Taken together, our behavioral and neurological findings provided evidence supporting expectation-based sentence comprehension in Korean.