This article describes a test of mood-as-input theory predictions as applied to a rumination task in a nonclinical population. An experimenter-controlled interview was used to allow participants to reflect on a personal period of depression while in an experimentally-induced mood state (either negative or positive) or while deploying a specific stop rule for the task (either an “as many as can” or “feel like continuing” stop rule). As predicted by mood-as-input theory, persistence at the rumination task was greatest in the group experiencing negative mood while deploying an “as many as can” stop rule, and this suggests a mechanism that may contribute to perseverative depressive rumination. It is argued that the variables that contributed to perseveration in this study are already known to be characteristic of ruminative thinkers (e.g. negative mood and positive metacognitive beliefs about rumination that will command the deployment of “as many as can” stop rules for rumination). It is also argued that mood-as-input processes may provide a common mechanism for perseverative rumination and perseverative worry, and this common mechanism may account for many of the similarities between these two functionally-distinct activities.
Rumination involves repetitive, prolonged, and recurrent thought about one's self and the causes, consequences and symptoms of one's negative affect (Nolen-Hoeksema, 1991 and Watkins, 2008). Such thought is commonly found in response to dysphoric mood and the losses and failures that may trigger dysphoric mood (Lyubomirsky and Nolen-Hoeksema, 1993, Lyubomirsky and Nolen-Hoeksema, 1995 and Nolen-Hoeksema and Morrow, 1993), and rumination has been found to be a risk factor for later bouts of depression, to exacerbate and prolong distress, and predict other psychopathologies such as binge eating and drinking (Nolen-Hoeksema and Harrell, 2002, Nolen-Hoeksema et al., 2008, Nolan et al., 1998, Robinson and Alloy, 2003 and Sarin et al., 2005). There is currently no clear consensus on what constitutes the content of ruminative thinking and how it should be measured, and this differs in accordance with the predictions derived from the various models that have been postulated to explain rumination (e.g. Smith & Alloy, 2009). Some models claim that rumination is focussed on negative emotional states such as ruminating on sadness (Trapnell & Campbell, 1999), others that it consists of dwelling on the negative aspects of previous losses and failures (Fresco, Frankel, Mennin, Turk, & Heimberg, 2002), while others claim it is an attempt to look for precipitants or sources of current distress (Watkins, 2004). Still others claim that the content of rumination consists of all of these components (Nolen-Hoeksema, 1991).
