An Electrophysiological Study of Noisy Channel Sentence Comprehension.
The present study employed Event Related Potential (ERP) paradigm to investigate on-line sentence comprehension containing deletion and insertion errors, compared to controls. We used prepositional-object (PO) plausible constructions such as (i) The aunt mailed the letter to her niece by post, compared to double-object (DO) implausible constructions (ii) # The aunt mailed the letter_her niece by post (deletion error). Besides, a DO plausible construction such as (iii) The aunt mailed her niece the letter by post, was compared to a PO implausible construction (iv) The aunt mailed her niece #to the letter by post (insertion error). Based on noisy Channel model propositions, language processing system acts as a rational comprehender and follows Bayesian size principle, which posits deletions are more likely to occur than insertions. This assumption would be held true if, comprehenders show differential sensitivity to different error types. Behavioural and ERP data from our study revealed the same. The brain responded with a sustained negativity (anterior) at head-noun position for deletion errors, while insertion errors elicited a long-lasting centro-parietal positivity at a later sentence position. The findings indicate that the language processing system is immediate in detecting anomaly and might engaged in a lexical search process (depicting higher workload) for deletion errors. The positivity observed for insertion error was thought to be associated with a repair process because of a clear availability of alternative plausible meaning due to semantic attraction. Together, these findings support the noisy channel model assumption for differential treatment of deletion versus insertion errors.
Language processing, Electroencephalography, Revision, Deletion Error, Bayesian principle
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