Pupillary response reflects vocabulary comprehension

It has been known that the pupil of the human eye responds not only to changes in brightness, but also those in cognitive activities. A recent study reported that pupillary dilation reflects one's ability to discriminate English sounds /l/ and /r/, suggesting that pupillary responses may be used to evaluate learner's listening comprehension. Presently, we recorded English learners’ pupillary responses in three situations: pre- (Control), in- (Study), and post-study (Test). We then classified our participants into two groups based upon their test scores (high and low), and compared their pupillary responses in the three situations. As the result, significantly different pupillary responses (dilatation) were observed between the two groups in Study. This result suggests that quantitative observation of pupillary responses may replace or be employed in parallel with traditional vocabulary tests to make vocabulary learning more efficient.