While most analyses of the definite DP island effect assume that it holds
for A' movement in general, a recent discourse-based approach
(Focus-Background Conflict constraint, Abeillé et al 2020) indicates that
only movement of focus (e.g. wh-movement) is sensitive to this island
effect and not other movement (relativization). Using a factorial design
comparing extraction out of DPs headed by the indefinite article and a
demonstrative (a vs. that), we found the island effect in both wh-questions
and relative clauses. We also found the island effect in relative clauses
with PP movement. These findings indicate that the aforementioned analysis
is not supported to account for the definite DP island effect.