Comparison of possible generation mechanisms for trial-averaged activity with additive amplitude and phase resetting. A, No stimulus response. Left, Sample single-trial oscillations before and after stimulus onset at t = 0. Center left, Signal averaged across 100 random trials. Center right, Wavelet coefficients for all trials 100 ms after stimulus onset. Red dot indicates center of mass. Right, Cross-trial measures relative to prestimulus period. B, Same as A, but with stimulus evoking a reliable waveform that is added to background oscillations. The cloud of wavelet coefficients is shifted in space without changing in shape, creating an increase in intertrial coherence and mean amplitude measures. C, Same as A, but with stimulus inducing a phase reset of existing oscillations. Wavelet coefficients are aligned to a narrow range of phases, creating an increase in intertrial coherence and R2 phase coherence.