Uncovering the nonlinear relationship between metacognitive strategy use and L2 achievement from the lens of the Island Ridge Curve: more is not always better

Metacognitive strategies are essential to second/foreign language (L2) acquisition. However, the individualized use of metacognitive strategies and their relation to L2 learning has been understudied. Guided by the theory of the Island Ridge Curve (IRC), the current study used latent profile analysis (LPA) to explore university students' unique patterns of metacognitive strategy use during L2 (English) acquisition. A total of 1180 undergraduates (freshmen and sophomores) participated in this study. Results of LPA revealed four profiles of strategy use: low, medium, high, and extremely high strategy profiles. Multinomial regression analysis indicated no significant effect of gender on the four strategy profiles but a significant negative effect of grade level on the extremely high strategy profile, meaning second-year students are less likely to overuse metacognitive strategies than first-year students. An analysis of variance showed that students' English achievement increased steadily from the low to the extremely high profile. However, a post hoc analysis indicated that the change in English achievement from the high to the extremely high strategy profile was non-significant. This nonlinear relationship provides further evidence reinforcing the fluid relationship between metacognitive strategies and English achievement. More importantly, this study validates the IRC theory in the context of L2 acquisition.