In "The Crucible", what behaviors of Betty Parris and Ruth Putnam made some feel they were possessed by witches?

When the play opens, Betty is presumably asleep on the bed and Reverend Parris is praying feverishly next to her. The reader learns that since Parris found the girls dancing naked in woods, Betty has not woken. The Purtains feels that something as simple as a sickness should be cured by now and by all of the prayers. They figure that it must be something stronger than illness. Betty also become agitated when hymn are sung and has been said to call for her mother (who is dead) and to try to fly out the window, all indications that she is not under her own control.