Plausibility and the garden path not taken: Online aural cue use in L1, L2, and heritage speakers of Mandarin

Online incremental sentence processing can differ due to age of acquisition (AoA). Garden-path (GP) sentences reveal comprehenders’ expectations during parsing and can be used to probe L1-L2 differences. GPs contain an initially misleading interpretation that requires syntactic revision after a disambiguation point, resulting in the GP effect, i.e., cost of abandoning the interpretation. However, when the initial GP interpretation is implausible instead of plausible, this serves as a cue to reduce commitment, mitigating the GP effect. Studies have shown that L1 speakers use plausibility cues in real time to impact commitment to the GP reading, while L2 speakers appear less able to use plausibility cues to mitigate the GP effect. Less is known about incremental cue use in heritage language (HL) speakers, who have early AoA but are nondominant in their heritage language. The present study investigates the online processing and offline interpretation of GPs by L1, advanced L2, and HL speakers of Mandarin. Mandarin GPs with plausible or implausible initial continuations were presented using a self-paced listening task. Results showed clear group differences. Offline, L1 and HL speakers exhibited high comprehension compared to L2 speakers, implicating early AoA in syntactic revision. Online, plausibility did not impact L1 RTs at any region, suggesting ceiling effects. In contrast, HL and L2 groups showed RT differences at the plausibility cue. Both groups also showed clear GP effects at the disambiguation, regardless of initial plausibility. This suggests the plausibility cue was processed but not utilized to impact the GP effect. However, interactions showed finer differences. For HL speakers, a significant interaction between Plausibility and Trial revealed that plausibility cue use influenced the GP effect incrementally over the experiment. This suggests that AoA plays an important role in online processing.