Why do you suppose Mary Warren changes her testimony at the end of Act Three? What might have happened to her if she hadn’t?

It's difficult to judge Mary Warren too harshly. She is young and easily manipulated. She does go along with Abigail's schemes but I tend to think this to be more out of fear than anything else. By the end of the play it would seem that Mary warren was developing a sense of justice. She testifies, despite being terrified of Abigail, that much of the girls' stories were in fact lies. She also stated that the doll was given to Elizabeth by her and the needle in its abdomen was placed by her. It seems like Mary had found some courage. At the orders of Abigail, the girls put on a performance while accusing Mary of casting spells. Mary finds herself in a dangerous position and recants her testimony. Instead she claims John Proctor made her lie. So had Mary changed? I think she did but she crumbles under the pressure. By the end of the play she must have been an emotional wreck, coming so close to doing the right thing but failing in the end. I don't think it would have made much difference if Mary had testified. The court needed to find witches to justify its own existence.