The most obvious example of psychological guilt appearing in Macbeth is when Lady Macbeth cannot stop herself from seeing th blood on her own hands. This happens in Act V, Scene 1 and is one of the most often quoted passages from this play:
Lady M. Out, damned spot! out, I say! One; two: why, then, ’tis time to do ’t. Hell is murky! Fie, my lord, fie! a soldier, and afeard? What need we fear who knows it, when none can call our power to account? Yet who would have thought the old man to have had so much blood in him?
This moment marks a culmination of sorts in her descent into psycholgical ruin as a result of her inability to continue to ignore her guilt. Throughout the play, Lady Macbeth is constantly aware of the guilt that she and Macbeth are taking upon themselves, and she seeks to absove the sin by washing it away. She encourages Macbeth to wash away the blood on his hands as well earlier in the play, in Act II scene 1 after the myrder of Duncan. All along, she seems to believe that as long as the evidence of the sin is washed away it is possible to absolve the guilt. That is, until the end of the play when the she cannot seem to make the stain os her evil deeds vanish by simply rinsing them with water.
Beyond the obvious, however, it is possible to analyze almost all of the characters in the play from a psychological perspective. Macbeth and Lady Macbeth are motivated by greed and a hunger for power. These are both psychological character traits that lead to their ultimate downfall. Banquo's ghost acts as an element of not only the supernatural but of the psyche as well. He is a reflection of the mind's need to ansolve and acknowledge guilt. The witch's constant presence as well shows how easily "religion" can impact and shape the actions of human beings.