"The older painting - well, it does have an effect all at once, I suppose, but it's of a lesser intensity than a lot of the American work in the last ten or fifteen years"

Donald Judd's quote is referring to the contrast between older paintings and American art work from the last decade or two. He believes that the older paintings have an impact, however it is not as strong as the American art work from the last ten to fifteen years. This might be due to the reality that American artwork has actually become more innovative and imaginative in recent years, enabling it to have a greater impact on viewers. Judd is most likely describing the rise of abstract expressionism, pop art, and other contemporary art motions that have ended up being popular in the United States. He believes that these motions have allowed American artwork to become more powerful and extreme than older paintings. This quote is a testimony to the development of art and how it has actually altered in time.