Temporal dynamics of central and peripheral processes in novel word acquisition: Evidence from co-registration of EEG and kinematics in natural handwriting.

Current models of handwriting production posit a hierarchy of cognitive subprocesses through which linguistic information cascades from central lexical encoding to peripheral motor execution. Yet it remains unclear how such cascaded coordination supports the formation of new memory traces for novel words. Here, we combined simultaneous electroencephalography and handwriting kinematics in native Spanish speakers (n = 63) to track word learning dynamics across repeated handwritten production. Event-related potentials (ERPs) time-locked to stimulus onset and kinematics-related potentials (KRPs) evoked by the motor execution of the critical letter revealed temporal coordination between central and peripheral learning effects as a function of repeated exposure, with exposure-driven modulation in the 173-309 msec after stimulus onset within a centro-frontal cluster and a comparable effect in the 133-286 msec post pen-down window over posterior sites. While orthographic encoding approached an asymptote after four exposures, motor refinement followed a more protracted trajectory across all encounters, indicating that the central and peripheral processes do not cascade to the same extent. The ongoing neural-kinematic coupling further revealed a parallel unfolding of motor planning and orthographic processing. Critically, the magnitude of exposure-induced neural modulation during learning predicted the strength of subsequent lexical competition in a masked priming lexical decision task after overnight consolidation. These findings substantiate the automatic nature of neural memory-trace formation coupled with cognitive and motor dynamics. The motor system continuously operates on partially specified linguistic information, establishing word-level orthographic representations before refining the letter-level graphomotor details on which lexical competition depends.