Let's be sure to define these terms before we go on to answer the question:
Direct Characterization: the author explains certain traits about a character directly to the reader
Indirect Characterization: the author shows the reader how the character acts during or reacts to different situations, building an understanding of the character
In Act II, here are some examples of each type:
DC: "I should have roared you down when you first told me your suspicion. But I wilted, and like a Christian, I confessed!" (59)
Miller has John tell the reader that he felt enough guilt over his sin (adultery) that he confessed to his wife when it would have been just as easy, if not easier, to lie and make her feel shame for suspecting him.
IC: "[The soup is] well seasoned." (54)
John, rather than scolding Elizabeth for ill-seasoned salt, instead compliments her on soup that he actually made better. This indicates that he cares more about having a positive relationship with her than about the soup itself.
IC: "But the proof! The proof!" (62)
Even though Mary is telling John that the court has accepted what she calls evidence as solid proof, he continues to question it. This shows that John does not blindly accept things just because he is told that they are true.