Rapid Orthographic and Delayed Phonological Processing: ERP and Oscillatory Evidence from Masked Priming in Korean

A central question in visual word recognition concerns whether orthographic and phonological codes are coordinated sequentially or in parallel during lexical access. Korean Hangul, an alpha-syllabic writing system with morphophonemic spelling principles, allows independent manipulation of orthographic and phonological syllable overlap within a single experimental design. In a masked priming lexical decision task with EEG, we contrasted orthographically identical primes (e.g., -), phonologically overlapping primes (e.g., -), and unrelated primes. Event-related potentials and time-frequency representations (theta: 4-8 Hz, lower beta: 13-20 Hz, upper beta: 20-30 Hz) were analyzed to capture both evoked and oscillatory neural dynamics. Orthographic priming produced a cascade of facilitative effects: early fronto-central P200 enhancement (150-250 ms) with upper beta synchronization (30-290 ms), followed by centro-parietal N400 reduction (350-550 ms) with frontal theta suppression (400-730 ms), and behavioral facilitation. Phonological priming, by contrast, elicited sustained lower beta activity over central regions (310-590 ms) but produced no early electrophysiological modulation and no behavioral facilitation. This spatiotemporal dissociation provides converging neural evidence that orthographic syllable processing emerges at pre-lexical stages and cascades into lexical-level processing, whereas phonological syllable effects are confined to later stages of lexical access. These findings provide support for a sequential or cascaded account of orthographic-phonological coordination, as predicted by dual-route models, while challenging strong forms of parallel activation, and suggest that the alpha-syllabic structure of Korean may enable a processing strategy in which orthographic parsing serves as an efficient entry route to the lexicon.