Well just to get you started I think that an obvious bit of evidence that conflict does, in fact, give us an insight into people's true natures is the way that Abigail acts when faced with impending conflict. It can be seen that she is manipulative and selfish in the way that she shifts blame and negative attention from herself and toward other, often innocent, people. The fact that she ran away because the conflict seemingly proved too severe for her to rectify without ridiculing herself can also be discussed here.
Similarly, the true goodness of John Proctor is displayed when he is faced with the tremendous decision of whether to lie and confess to dealing with the devil and live, or to not confess and die a noble, christian death. It is shown that in the face of overwhelming consequences, he chooses to preserve his image and die a good man.
Then maybe you could discuss that in some cases conflict doesn't expose the true, underlying nature of a person, and it in fact inhibits the exposure of such things.
Maybe you could find a good example of a situation in which a person has become more introverted or secretive as a result of conflict. I'm having a bit of a mental blank right now haha...
A slightly different example for this would be the fact that Elizabeth Proctor, known throughout the play to be very honest in everything that she says or does, has a single deviation from what is her true character when confronting the ordeal and when potentially the entire case and lives of those involved was at stake. (When she lied about John's affair with Abigail in the courtroom to Danforth)
I would then go on to discuss something a little more complex, such as the fact that people's true nature is not absolute and it can in fact be altered by conflict.
The transformation of Reverend Hale could possibly be used here, as he clearly changes from one who is involved directly in the conviction of some residents of Salem for witchcraft to one who is trying to save the lives of those whom are set to be hanged. This is a good example of an internal conflict which has been provoked and affected by external stimuli.
I haven't included any external/real life/historical examples because I haven't personally got a great arsenal of external examples at the moment, our SAC isn't for another week or so and I like to have them fresh in my memory.
Also, I just remembered, my teacher was stressing today that we don't neglect characters such as the Putnams and particularly Parris, which he said can often happen. They are instrumental in actually initiating and provoking the whole idea of witchcraft in the light of Betty's apparent unconsciousness and also because of Ann Putnam's misfortune with childbirth.