Rumination is defined as the compulsively focused attention on the symptoms of one's distress, and on its possible causes and consequences, as opposed to its solutions. Rumination is similar to worry except rumination focuses on bad feelings and experiences from the past, whereas worry is concerned with potential bad events in the future. Both rumination and worry are associated with anxiety and other negative emotional states.
Extensive research on the effects of rumination, or the tendency to self-reflect, shows that the negative form of rumination interferes with people’s ability to focus on problem-solving and results in dwelling on negative thoughts about past failures. Evidence from studies suggests that the negative implications of rumination are due to cognitive biases, such as memory and attentional biases, which predispose ruminators to selectively devote attention to negative stimuli.
The tendency to negatively ruminate is a stable constant over time and serves as a significant risk factor for clinical depression. Not only are habitual ruminators more likely to become depressed, but experimental studies have demonstrated that people who are induced to ruminate experience greater depressed mood. There is also evidence that rumination is linked to general anxiety, post traumatic stress, binge drinking, eating disorders, and self-injurious behavior.
Rumination was originally believed to predict the duration of depressive symptoms. In other words, ruminating about problems was presumed to be a form of memory rehearsal which was believed to actually lengthen the experience of depression. The evidence now suggests that although rumination contributes to depression, it is not necessarily correlated with the duration of symptoms.
Three forms of rumination were proposed by Mikulincer (1996):
- State rumination, which involves dwelling on the consequences and feelings associated with the failure. State rumination is more common in people who are pessimistic, neurotic, and who have negative attributional styles.
- Action rumination, which consists of task-oriented thought processes focused on goal-achievement and correction of mistakes.
- Task-irrelevant rumination, which utilizes events or people unassociated with the blocked goal to distract a person from the failure.
The tendency to ruminate can be assessed with the Ruminative Responses Scale of the Response Styles Questionnaire. On this measure, people are asked to indicate how often they engage in 22 ruminative thoughts or behaviors when they feel sad or blue.
Gender differences 
According to Susan Nolen-Hoeksema, women tend to ruminate when they are depressed, whereas men tend to distract themselves. This difference in response style was proposed to explain the higher rates of depression in women compared to men. Researchers have confirmed the greater likelihood of rumination in women, though the prediction that men are more likely to distract themselves has not been consistently supported.
Healthy self-disclosure 
Although rumination is generally unhealthy and associated with depression, thinking and talking about one's feelings can be beneficial under the right conditions. According to Pennebaker, healthy self-disclosure can reduce distress and rumination when it leads to greater insight and understanding about the source of one's problems. Thus, when people share their feelings with others in the context of supportive relationships, they are likely to experience growth. In contrast, when people repetitively ruminate and dwell on the same problem without making progress, they are likely to experience depression. Co-rumination is a process defined as “excessively discussing personal problems within a dyadic relationship” (Rose, 2002), a construct that is relatively understudied in both its negative and positive trade-offs.
See also 
- Major depressive disorder
- Obsessive compulsive disorder
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