Mary, who has trichotillomania (chronic hair pulling), is enrolled in a single-subject study using an ABAB design to see if she pulls more hair while watching TV. Mary watched TV during dinner for 4 weeks and pulled at least ten hairs a day for those 4 weeks. Then she left the TV off for 4 weeks and pulled only one hair per day for the 4 weeks. In the next step of this design, the experimenter should ask Mary to