Prestimulus α Band Power and Phase Predict Visual Awareness

Abstract People are often unaware of objects that are easily aware of at other times. Because the visual target itself is constant, this change may be attributed to fluctuations in cortical excitability. It is measured mainly by the power and phase of the oscillation in the prestimulus α-band. The predictive effects of prestimulus α and β on visual awareness were studied by using the low-contrast stimulus paradigm and EEG time-frequency analysis, and the PAS scale was used to analyze different levels of awareness. The power in the prestimulus α band was significantly lower in the aware condition than in the unaware condition and significantly lower in the high-awareness condition than in the low-awareness condition. Aware and unaware as well as high and low awareness were located at different phase angles. The proportion of aware and high awareness decreased with the increase in the power bin of α. The power and phase of prestimulus β did not predict awareness and awareness levels. The results showed that the power and phase of the prestimulus α-band predicted visual awareness and its level. The greater the power of the prestimulus α is, the lower the likelihood of being aware of the target and the lower the level of awareness.