Saturday, September 27, 2014

Paper submitted: The importance of reading naturally

Here is a new paper from our lab: Abstract: Traditionally, a lot of ERP research on language processing uses auto-paced, word-by-word presentation. What is the difference in ERP effects between word-by-word presentation and natural reading? We investigated this question by conducting two experiments; event-related brain potentials were recorded while participants read either word-by-word or naturally. In the natural reading experiment, eye movements were recorded concurrently with the brain potentials. Comprehension difficulty was induced by syntactic (gender mismatch) or semantic violations (implausible association of adjective and noun) that occurred either sentence-medially or sentence-finally. This design allowed us to investigate whether recovery from unexpected input differs in the two modalities. Both the word-by-word and natural reading experiments showed the classical N400 and P600 effects seen in syntactic and semantic violations, replicating published results. However, compared to word-by-word presentation, natural reading led to higher accuracy in judging well-formedness of sentences; and in natural reading, trials with regressive eye movements led to higher accuracy than trials without regressive eye movements. Interestingly, in the sentence-medial violations, a P600 effect was observed when regressions occurred, suggesting that a regressive eye movement event is associated with a recovery process. By contrast, when no regression occurred, no effect was seen in the brain potentials sentence-medially, implying that no recovery process was triggered. In sentence-final position, both violations led to N400 and P600 effects in regression trials, and a sustained negativity in no-regression trials, the latter suggesting that the reader may have detected the violation but was willing to tolerate it. In sum, we show that natural reading leads to higher comprehension accuracy than word-by-word presentation. Additionally, the separation of regression and no-regression trials revealed the strategic choices made by the comprehension system. Thus, although the relative simplicity of the word-by-word presentation paradigm offers clear advantages, important aspects of language comprehension can perhaps be better studied using natural reading.