Phase weighting: a method to improve objective detection of steady-state evoked potentials

Objective response detection statistics such as magnitude-squared coherence (MSC) reflect the degree to which subaverage phases are clustered or dispersed, but not their agreement with an expected, or target, phase. Using signal-plus-noise simulations and human 40-Hz auditory evoked potentials, we tested MSC performance with and without phase weighting, in which MSC values were multiplied by weights related to the phase error between measured phase and target phase. Phase weighting improved MSC performance for both simulated and 40-Hz auditory evoked potential data. However, the improvement was greater for the simulations, probably because target phase was precisely known.