Really?

They needed a study to figure this out? Toddlers throw tantrums. Thats thier job! or part of it at least. Anyone who's had a toddler could tell you that. I would submit that it is part of them learning thier boundries in life as they have learned to walk and talk by then. This process has gone on for thousands of years and has worked just fine. If it isn't broken, don't FIX it!

http://news.yahoo.com/s/afp/20080201/ts_afp/healthchildrenpsychologyparenting