Differences in implicit vs. explicit grammar processing as revealed by drift-diffusion modeling of reaction times
Learning new languages is a complex cognitive task involving both implicit and explicit processes. Batterink, Oudiette, Reber, and Paller (2014) report that participants with vs. without conscious awareness of a hidden semi-artificial language regularity showed no significant differences in grammar learning, suggesting that implicit/explicit routes may be functionally equivalent. However, their operationalizing of learning via median reaction times might not capture underlying differences in cognitive processes. In a conceptual replication, we compared rule-aware (n=14) and rule-unaware (n=21) participants via drift-diffusion modeling, which can quantify distinct subcomponents of evidence-accumulation processes (Ratcliff & Rouder, 1998). For both groups, grammar learning was manifested in non-decision parameters, suggesting anticipation of motor responses. For rule-aware participants only, learning also affected bias in evidence accumulation during word reading. These results suggest that implicit grammar learning may be manifested through low-level mechanisms whereas explicit grammar learning may involve more direct engagement with encoded target meanings.