What's wrong with Betty Parris in The Crucible?
A careful reading of the text indicates that there are a number of things wrong with Betty Parris.
The first and most obvious, initially, is her physical condition. When the play opens, we learn that she is lying inert on her bed with her father, Reverend Parris, the local priest, kneeling beside her bed, supposedly praying. Betty is unconscious.
The reverend is clearly in distress and we later discover that he had sent Susanna Walcott to the local doctor, Dr Griggs, to establish whether he had discovered a reason for Betty's condition. It is evident that the doctor had made an earlier visit. Parris is alarmed when Susanna tells him, on her return, that the good doctor, "...cannot discover no medicine for it in his books."
The reverend becomes quite agitated and anxious when Susanna further informs him that the doctor has said,
...he have been searching his books since he left you, sir. But he bid me tell you, that you might look to unnatural things for the cause of it.
The reason for Betty's sickness is clarified when we read in Parris' conversation with Abigail, his niece, that he had caught Betty and her, with other girls, dancing around a fire in the forest at night. He surprised them with his sudden appearance and Betty fainted immediately, probably from sheer terror and shock. It seems that her condition at this point is a genuine reaction brought about by the immense distress she must have felt on being discovered performing a ritual which is taboo in Salem society and which could have serious consequences, especially since her father runs the local parish.
Betty later suddenly recovers when Abigail threatens to beat her and tells her that she has already spoken to her father. Betty is clearly afraid of Abigail and jumps up screaming that she wants to go to her deceased mother. She is so distraught that she threatens to jump out of the window in an attempt to 'fly to mama.'
It is also clear that Reverend Parris has no skill in working with children. The author's notes inform us that:
He was a widower with no interest in children, or talent with them. He regarded them as young adults,...
This informs us of another problem Betty has. She lacks the love and comfort of a mother and has only Abigail to use as a role model. She was largely raised by Tituba, the reverend's slave from Barbados, who most probably also had much influence on her young mind. Furthermore, Betty is clearly afraid of both her father and her cousin, Abigail, whose own parents had been brutally murdered, so when Abigail threatens 'a pointy reckoning' to any of the girls if they speak about what they did in the forest, one can just imagine how frightened Betty must be.
It is these fears which drives Betty to lie in court and join the other girls to falsely accuse and implicate innocent residents of witchcraft. The girls' shenanigans in court are so convincing that the judges and prosecution are easily led to believe their pernicious testimony.
When the play opens, Betty Parris is in a comatose state, unable to wake. The doctor is unsure about the cause, and advices Parris that there is nothing physically wrong with her, and that he should perhaps look elsewhere for answers. As the act unfolds, we learn that the children were found by Parris dancing in the forest the evening before. According to Abigail Williams, Rev. Parris' niece, Betty is simply scared of the ramifications for dancing. In her fright, she has blacked out. Parris, under the direction of the Putnams, believes that someone may be "witching" his daughter, causing this illness as an attack against him and his family. Based on later events in the Act, such as Betty's outburst for her mother and her accusation to Abigail about conjuring spirits, the audience is left to believe that perhaps nothing is really wrong with Betty, but that out of fear of being beaten for dancing, she is pretending.