Dual-route processing of horizontally and vertically jumbled Chinese words: evidence from ND250 and LAN

Previous research suggests that visual recognition of two-character Chinese compound words relies on a dual-route mechanism involving whole-word orthographic processing and morphological decomposition, both of which remain engaged for horizontally presented jumbled words. The present study investigated whether this flexible dual-route mechanism generalizes to vertically presented jumbled words and whether the two processing routes differ in their sensitivity to presentation orientation (horizontal vs. vertical) and character order (canonical vs. jumbled). Event-related potentials (ERPs) were measured during an implicit reading task, in which two-character Chinese words and pseudowords were presented under four conditions: horizontal canonical, horizontal jumbled, vertical canonical, and vertical jumbled. Both ND250 and left anterior negativity (LAN) effects were reliably elicited across all four conditions, indicating that both processing routes remain engaged across presentation orientations and character orders. ND250 mean amplitude showed an interaction between presentation orientation and character order, and ND250 peak latency was affected by presentation orientation, indicating that whole-word orthographic processing is sensitive to visuospatial organization. In contrast, neither LAN amplitude nor peak latency was affected by either factor, suggesting that decomposition-related processing is relatively stable across spatial configurations.