I often get questions like this: My child displays problem behavior (screams/argues/ bites/kicks/flops to the ground ) when a demand is placed (it is time to take a bath/do homework/go to bed). The answer to the question is similar no matter what the problem behavior or demand.
Whenever problem behaviors occur, I believe the demands are usually too high and/or the reinforcement is too low.
The first thing I would recommend is to take data (how many times the behavior occurs per hour or per day and take some ABC data too, if possible). Next I would look at activities when the problem behavior almost always occurs (when it is time to take a bath) and when it never occurs (while your child is playing on the computer).
You then should look at ways to “re-pair” the bathing routine (get foam for the tub or bath paint/toys for instance) and try to sandwich harder activities with fun activities (first bath then computer). A heavy focus on pairing and manding as well as an 8 to 1 ratio for positive to negative comments is usually helpful too.
Continuing to take data while you intervene is necessary to make sure the behaviors are decreasing. If problem behaviors are severe you may need a Board Certified Behavior Analyst (BCBA) or someone with lots of experience with problem behaviors to help you. My book (The Verbal Behavior Approach) –specifically chapters 2, 4, and 5 explain these ideas more fully. I also go over all this and more in my Autism ABA Help Course, so take a look!