Pupil Dilation Response to Prosody and Syntax During Auditory Sentence Processing

Pupil dilation response has been shown to reflect different levels of sentence processing during prosodic and syntactic processing in language comprehension. Our pupillometry experiment aimed to investigate whether pupil diameter was sensitive to the auditory sentence processing involved in comprehending congruent and incongruent statements. Twenty-one participants were presented with 300 auditory stimuli consisting of syntactically and/or prosodically congruent and incongruent sentences in Turkish. The pupillary response results were significant only for syntactically incongruent sentences and for sentences that were both syntactically and prosodically incongruent. This indicates that prosody had no significant effect on its own. Based on the hypothesis that prosodic and syntactic processing require cognitive sensitivity for auditory sentence comprehension, we expected an increase in pupil diameter for both processes. However, our findings are consistent with the previous assumptions that pupil size increases during syntactic manipulation, but our findings showed that prosodic processing does not increase pupil size, contrary to previous studies.