Recent studies of second language (L2) construction learning using artificial linguistic systems have begun to closely examine the role of individual differences, including personality. In such studies, adult participants learn form-meaning mappings after exposure, with scores on generalization tests as a standard criterion for learning. This paper addresses the potential role of openness in explicit versus implicit knowledge. The present research relied on a reanalysis of data from a previous study, using an extreme-groups design involving 60 participants. It was revealed that scores when using implicit versus explicit knowledge sources varied by openness. In particular, though both groups performed significantly above chance when using rules, only open learners did so when using intuition. Furthermore, learners with higher openness scores outperformed those lower in openness, based on mixed-effects regression models. This preliminary evidence for the role of openness is discussed in terms of its theoretical and methodological implications.