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. In a masked priming lexical decision task with EEG (N= 30), we contrasted orthographically identical primes (e.g., 식-식량), phonologically overlapping primes (e.g., 싱-식량), 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 msec) with upper beta synchronization (30-290 msec), followed by centro-parietal N400 reduction (350-550 msec) with frontal theta suppression (400-730 msec), and behavioral facilitation. Phonological priming, by contrast, elicited an inhibitory behavioral effect and sustained lower beta activity over central regions (310-590 msec) but produced no early electrophysiological modulation, consistent with lexical competition. This spatiotemporal dissociation suggests that orthographic syllable processing can emerge at early stages and cascades into later lexical-level processing, whereas phonological syllable effects are confined to later processing stages. 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.