Knowledge and Processing of Morphosyntactic Variation in African American Language and Mainstream American English

As people from different social groups come into contact, they must accommodate differences in morphosyntax (e.g., He seem nice vs. He seems nice) in order to successfully represent and comprehend their interlocutor’s speech. Listeners usually have high comprehension across such differences, but little is known about the mechanisms behind morphosyntactic accommodation. In this dissertation, I asked what listeners know about variation in morphosyntax and how they deploy this knowledge in real-time language processing. As a test case, I focused on regularized subject-verb agreement (e.g., He seem nice, They was happy)—which is common in African American Language (AAL), but not in Mainstream American English (MAE)—and compared how listeners adjust their linguistic expectations depending on what language varieties both they and their interlocutors speak. In Experiment 1, I showed that participants who primarily speak MAE 1) recognize that some speakers use regularized subject-verb agreement, 2) evaluate that regularized subject-verb agreement is associated with AAL, and 3) predict that the subject-verb agreement rules of AAL allow for some patterns (They was happy) but not others (*He were happy). This was accomplished using a novel sentence rating task, where participants heard audio examples of a given language variety, then rated written sentences for how likely a speaker of that variety would be to say them. In Experiment 2, I showed that a similar pool of participants did not merely recognize regularized subject-verb agreement; their knowledge of variation lead them to predict that AAL speakers use regularized forms in an acoustically ambiguous context. Participants heard sentences like He sit(s) still, where it is unclear whether the verb includes a verbal -s due to a segmentation ambiguity. They were more likely to transcribe a regularized form (He sit still) when it was spoken by an AAL-speaking voice than when it was spoken by an MAE-speaking voice. Together, t