Task-evoked Pupillary Response for Completely Intelligible Accented Speech

Speech perception under adverse conditions, such as those caused by noise in the environment or a speaker’s accent, can be cognitively demanding. For second language- (L2-) accented speech, mismatches between the speech patterns of an L2-accented speaker and a listener can result in poorer understanding and reduced intelligibility (i.e., fewer words in the speech stream can be correctly identified). However, it remains unclear whether completely intelligible L2-accented speech imposes greater cognitive load (defined here as the degree to which cognitive resources are recruited at a given moment to meet processing demands) than native speech. In the current study, we used pupillometry to examine cognitive load during the perception of completely intelligible, Mandarin Chinese-accented English speech and standard American-accented English speech. Results from two experiments showed greater and more rapid pupillary response (indicating greater cognitive load) for L2-accented speech than native speech. Additionally, participants subjectively rated the L2-accented speaker as more effortful to understand than the native speaker. Consistent with an executive recruitment account for accented speech, these findings indicate that mismatches between the speech patterns of L2-accented speech and native listeners’ representations require greater cognitive load to process—even when recognition accuracy is at ceiling