In this paper we show that a standard measure of rumination has two key components: an affective component that we call brooding and a cognitive component that we call pondering. Brooding and pondering are shown to have different relations to depression. This paper has led to much work, including brain imaging studies showing different networks and localization for the two components.

Treynor, W., Gonzalez, R., & Nolen-Hoeksema, S. (2003). Rumination reconsidered: A psychometric analysis. Cognitive Therapy and Research, 27, 247-259. doi:10.1023/A:1023910315561 (PDF)

Susan Nolen-Hoeksema passed away Jan 2013. See the New York Times.

Here is the Ruminative Responses Scale, with a note from Susan, which to my knowledge was last emailed on 10/22/2012. Here is more detail on the Rumination scale.

Abstract

In an attempt to eliminate similar item content as an alternative explanation for the re- lation between depression and rumination, a secondary analysis was conducted using the data from S. Nolen-Hoeksema, J. Larson, and C. Grayson (1999). After construct- ing a measure of rumination unconfounded with depression content, support for a two factor model of rumination was found. These analyses indicate that the 2 components, reflective pondering and brooding, differentially relate to depression in terms of pre- dictive ability and gender difference mediation. The results presented here support the general premise of Nolen-Hoeksema’s Response Styles Theory (S. Nolen-Hoeksema 1987) that rumination can contribute to more depressive symptoms and to the gender difference in depression, but suggest important refinements of the theory. Such refine- ments include the need to differentiate between the reflective pondering component of rumination and the brooding component in rumination research.