The variability of weak visual stimulus detection and discrimination has been associated with oscillatory brain activity. Subjective visibility, attention, and decision confidence have all been influenced by the amplitude of activity in the alpha-band (8–12 Hz), in particular. For a study, researchers sought to record simultaneous subjective measures of attention and confidence (experiment 1) or attention and visibility (experiment 2) on a trial-by-trial basis in a visual detection task to examine how anticipatory alpha in a cued pre target period effects performance and phenomenology. 

Alpha amplitude was linearly and adversely linked with the degree of perceived attention across both tests. They found a quadratic link between the intensity of alpha oscillations and subjective assessments of visibility and confidence, as opposed to the linear relationship. 

They discovered that alpha amplitude and the potency of stimulus-evoked responses are related by the same quadratic relationship. The intensity of the evoked responses likewise correlated with visibility and confidence judgements, although only confidence took the attentional state into account. 

Therefore, when these judgments were preceded by a cued target interval, the findings showed unique psychological and neurological correlates of attentional state, stimulus visibility, and choice confidence assessments.

Reference: jov.arvojournals.org/article.aspx?articleid=2783680