Reacting in any way at all means the child gains the "reward" of your attention, or other people's attention for however long it lasts (remember it is supposed to be the most needed factor for us all psychologically to have either "positive strokes" or "negative strokes" than to be ignored).
I know it isn't easy to avoid paying attention to your child's attempt to manipulate or join in the manipulation going on around them - maybe you have to do something, sometimes. However, being a "nuturing parent" will still be seen as a "reward" by the child - they got you to do something you wouldn't otherwise have liked to be doing (i.e. responding to their manipulation).
If you haven't read up on this psychology theory I could try to find web links for you.
All the best, Graham