Action painting was predicated on the idea that the creative process involves a dialogue between the artist and the canvas. Just as the artist affects the canvas by making a mark on it, that mark in turn affects the artist and determines the trajectory of the next mark. As art critic Harold Rosenberg explained, "[e]ach stroke had to be a decision and was answered by a new question." While spontaneity is key to action painting, it is always within the parameters of this dialogue. Artists to be examined include Franz Kline, Jackson Pollock, Lee Krasner, Grace Hartigan, and Joan Mitchell, among others.