Contrasting mechanistic accounts of the lexical boost.

While many recent studies focused on abstract syntactic priming effects have implicated an error-based learning mechanism, there is little consensus on the most likely mechanism underlying the lexical boost. The current study aimed at refining understanding of the mechanism that leads to this priming effect. In two eye-tracking during reading experiments, the nature of the lexical boost was investigated by comparing predictions from competing accounts in terms of decay and the requirement of structural overlap between primes and targets. Experiment 1 revealed facilitation of target structure processing for shorter relative to longer primes, when there were fewer intervening words between prime and target verbs. In Experiment 2, significant lexically boosted priming effects were observed, but only when the target structure also appeared in the prime, and not when the prime had a different structure but a high degree of lexical overlap with the target. Overall, these results are most consistent with a short-lived mechanistic account rather than an error-based learning account of the lexical boost. Furthermore, these results align with dual-mechanism accounts of syntactic priming whereby different mechanisms are claimed to produce abstract syntactic priming effects and the lexical boost.