Reassessing L2 Sensitivity to Island Constraints: Asymmetries Between Wh-Islands and Adjunct-Islands

Boyoung Kim^*

• Sungshin Women's University, Seongbuk District, Republic of Korea

This study investigates Korean L2 speakers' sensitivity to English island constraints, focusing on the widely reported asymmetry between wh/whether-islands and adjunct-islands. Using a factorial definition of island effects, we quantified island penalties while independently estimating the costs of dependency-length and structural-complexity. Acceptability judgment results showed that native speakers displayed robust island effects across all types, whereas L2 speakers displayed significant effects for adjuncts (because-and when-clauses) and whether-islands but no significant interaction for wh-islands, indicating weaker sensitivity. The overall magnitude of island effects was smaller in L2 speakers and decreased systematically with later Age of Arrival (AoA). Despite these differences, both groups exhibited the same gradient hierarchy of island strength (wh < whether < adjuncts) and comparable structural complexity costs (wh > whether > adjuncts), indicating fundamentally similar representations of island structure. L2 speakers, however, showed greater dependency-length costs—especially with later AoA—which appear to reduce the contrast between non-island and island configurations, yielding smaller observable island effects. This pattern was most pronounced for wh-islands, which combine high structural complexity with the weakest island effects, creating the appearance of an L2-specific asymmetry despite otherwise native-like sensitivity. Overall, the findings suggest that L2 speakers' island sensitivity is native-like in kind but reduced in degree, reflecting quantitative rather than qualitative differences between groups.