My DD started something very similar around 7-8 as well, and just recently (just turned 9) seems to be coming out of it. I don't remember going through a phase like that as a child, but it's possible I did and just don't remember or see it as such. I have tried to not argue or turn the attitude back on her. Most of the time, I send her to her room to be alone until she can put away the attitude and act like the sweet girl I know she is. Some days, that method worked well enough, others, though, she was stubborn and we had to end with a form of discipline.