Autocorrelation and cross-correlation analyses of alpha waves in relation to subjective preference of a flickering light

To clarify the relationship between the human brain activity and subjective preference of a flickering light under changing temporal frequency and mean luminance, alpha waves were analyzed by autocorrelation function (ACF) and cross-correlation function (CCF). Paired-comparison tests were performed to examine the subjective preference of a flickering light. Electroencephalograms (EEGs) were recorded from 7 electrodes (10-20 system) during presentations of the most preferred and the least preferred flickering-light conditions. From the initial delay range of the ACF, the effective duration (τ_e) was determined to describe the temporal characteristics of the alpha waves. Results show that the preferred flickering light has a significant larger τ_e than that of the least preferred flickering light especially at the occipital area. In addition, the maximum value of the CCF (|φ(τ)|_max) between the alpha waves and its delay time were analyzed. Results show that the preferred flickering light has a significant larger |φ(τ)|_max than that of the least preferred flickering light.