This is a great question. It is also an impossible question, because nobody knows. We don't get to see the girls in the forest. We only get to see and hear what they say happened, and what the others conclude.
We know Parris says he saw a kettle. We know that the girls (in Act I) first say they just did "common dancing," and then change stories to say that Tituba called the devil. Tituba denies that she called the devil, but then changes stories to say that there were witches there. The girls then change their stories to say they saw women from the town with the devil.
What happened? Do you believe them under pressure? Were they playing around? Running a scam? Possessed? We have only their testimony to go on, and so we can't be sure.