Position-Related Centro-Parietal ERP Responses During Contextual Processing Across Symbolic Domains

Many cognitive processes depend on integrating information as it becomes available to construct meaningful interpretations. Prior work has shown graded context effects, especially in language, but it remains less clear how ERP activity changes across successive positions in structured sequences from different symbolic domains. Twenty-seven participants processed structurally comparable four-element sequences across lexical, algebraic, and graphical domains, in which elements A to C established the context and D completed the sequence, while event-related potentials were recorded. In the 250-500 ms interval, centro-parietal mean amplitude showed a robust positive ordinal effect of sequence position (p <.001). Adjacent amplitude changes were unequal: the final C-to-D transition was substantially larger than both the A-to-B and B-to-C transitions (both p <.001). The largest amplitudes occurred over parietal sites, whereas position sensitivity was clearest over central sites. A categorical 0-180 ms analysis showed position-dependent early-window activity, but did not reproduce the defining late C-to-D-dominant profile. These results identify a clear late position-related ERP trajectory as structured meaning develops across the sequence and reaches task-relevant completion. Element D concentrates contextual completion, comparison, and response-related operations, which may have contributed to the enlarged final transition. The pooled ordinal effect demonstrates sequence-position sensitivity in the combined cross-domain dataset, whereas transition-level differences indicate domain-specific implementation of this trajectory.