Economy and symmetry in across-the-board movement: evidence from acceptability judgments in L2 English

Across-the-Board (ATB) movement has long served as a testing ground for theories of displacement and coordination. The Coordinate Structure Constraint (CSC) bans extraction from a single conjunct, yet canonical ATB structures are consistently well-formed, revealing the role of deeper conditions, economy, symmetry and PF linearization, in licensing. This study asks whether such conditions also shape interlanguage grammars, where overt morphological cues are limited. We report an acceptability-judgment experiment with adult Jordanian learners of L2 English, testing four ATB subtypes, relativization, wh-movement, comparatives and topicalization, against closely matched non-ATB controls. The results show a gradient: relativization-ATB > wh-ATB ≈ control > comparative-ATB ≫ topicalization-ATB, with no significant effect of proficiency. We argue that this profile reflects independently motivated principles of the Box System: Minimal Yield penalizes enlarged workspaces, Box Accessibility requires a single operator to remain simultaneously accessible across conjunct edges, and PF linearization disfavors crossings and adjacency violations. Analyses using both logistic and cumulative-link mixed-effects models (CLMM) converge on this hierarchy. Convergence with multidominance/remerge and sideward-movement accounts places the source of ATB asymmetries in derivational economy and symmetry, not morphology or frequency. The findings demonstrate that L2 grammars encode fine-grained structural constraints, extending minimalist theory of ATB movement to the domain of interlanguage syntax.