Semantic and structural anomaly processing across arithmetic and natural language: An ERP study

Whether arithmetic and language rely on shared or distinct processing mechanisms remains unresolved, particularly at the level of semantic and structural anomaly processing. The present EEG study addressed this question by comparing three written expression types: symbolic arithmetic, verbal arithmetic in Russian, and factual statements in Russian. Thirty-nine native Russian-speaking adults read segmented expressions and made explicit judgments about semantic correctness, while structural violations remained task-irrelevant. Semantic and structural correctness were manipulated orthogonally, and event-related potentials were analyzed with a priori focus on the N400, LAN, and P600. Semantic anomalies elicited a robust N400-like response across all three expression types, indicating broadly comparable meaning-related anomaly processing. Structural effects, however, were more dependent on representational format and processing stage. In earlier time windows, the clearest 300-500 ms structural effect was observed in symbolic arithmetic under the present local anomaly manipulations, although this early difference may partly reflect greater transparency of the symbolic structural violation. In the later P600 range, both symbolic arithmetic and factual statements showed significant structural-anomaly positivities, whereas no reliable comparable effect was detected for verbal arithmetic. These findings argue against both a fully shared and a fully segregated account of arithmetic- and language-related processing. Instead, they suggest a stage-dependent pattern of partial convergence and divergence. Semantic anomaly processing was broadly similar across expression types, whereas structural anomaly processing was more format-sensitive. Verbal arithmetic did not show a stable intermediate ERP profile across components under the present task and materials, suggesting that verbalized arithmetic should not be treated simply as symbolic arithmetic in words or as ordinary language with numerical content.