frequency resolution of 0.125 Hz, rather than the 0.5-Hz resolution of the original data. We used “gravity frequency” (see Klimesch, 1999 for a discussion), which involves weighting power estimates at each spectral frequency within the alpha band by its corresponding frequency, represented in the formula Σ(a(f) × f)/Σ a(f) where a(f) represents power at a given frequency, f. This weighted frequency measure is particularly advantageous when the power spectrum consists of multiple peaks in the alpha band (Klimesch, 1999). We calculated peak frequency between 7 and 14 Hz.
