Irina Lavrova¹, Anto J. Mohan², Miranda Scolari³; ¹Texas Tech University, ²Texas Tech University, ³Texas Tech University

Implicit learning is a phenomenon by which the extraction and acquisition of structural regularities occur unintentionally and without conscious awareness. This study examined whether eye movement patterns, which function as involuntary indicators of acquired knowledge (Silva et al., 2017), can be a reliable measure of implicit knowledge acquisition. A visual artificial grammar learning (AGL) task was used to explore the formation of implicit knowledge following a brief exposure to grammatical sequences. Sixty-five participants first made a same/different judgment for each presented pair of words created using artificial grammars of varying complexity. Importantly, they were not instructed to encode the words. Next, participants completed a surprise grammaticality judgment task, in which they decided whether each singly presented word followed the artificial grammar rules encountered in the first phase. Eye tracking revealed that participants exhibited eye movements patterns consistent with implicit learning. Dwell time was greater on target letters that violated the grammatical rules compared to non-target controls (χ2 = 4.57, p = 0.032), and targets were similarly associated with a greater number of regressions (χ2= 24.89, p < 0.001). Grammar complexity did not significantly influence eye movements, despite previous studies showing it negatively impacts performance on behavioral AGL tasks (Van Den Bos & Poletiek, 2008). Furthermore, eye movement patterns were not linked to grammaticality judgment accuracy, indicating that dwell time and regressions to target locations reflect an earlier, pre-awareness stage of processing. These findings highlight that eye-tracking can effectively capture implicitly acquired knowledge, revealing participants' sensitivity to grammatical structures even in the absence of conscious discrimination between grammatical and nongrammatical sequences. This underscores the role of perceptual processes in implicit learning and positions eye-tracking as a powerful tool for studying the unconscious acquisition of structural regularities.