Selective biases in attention can be modified by a simple computerized technique: The Attention Bias Modification Task (ABM) pioneered by MacLeod et al. Cognitive biases may be one reason depression recurs, and altering these biases should reduce risk of recurrence. Recently, evidence has supported this hypothesis . The mechanisms by which ABM works are not well understood. More research is needed to explore how altering an implicit attentional bias can lead to changes in subjective mood. One possible explanation is that positive attentional biases are an important component of explicit methods of emotion regulation. The ability to effectively regulate one's emotions is a fundamental component of mental health and this ability is impaired in depression. It has also been shown that recovered depressed people spontaneously show a more dysfunctional pattern of emotion regulation as compared to never depressed controls. Supporting this, growing evidence implicates dysregulation of a medial/orbitofrontal circuit in mood disorders. This circuit includes the orbitofrontal cortex and anterior cingulate cortex, the ventral striatum, the ventral pallidum and medial thalamus. Components of this circuit are reciprocally connected with the amygdala, which is implicated in emotional processing in the healthy brain and dysregulated in depression. Negative emotion processing biases depend on both enhanced "bottom-up" responses to emotionally salient stimuli and reduces "top-down" cognitive control mechanisms, required to suppress responses to emotionally salient but task irrelevant information. Cognitive reappraisal and distancing are common strategies to down- or upregulate emotional responses. Reappraisal is an emotion regulation strategy that involves reinterpretation and changing the way one thinks about an event or stimulus with the goal of changing its affective impact. Distancing is a type of reappraisal that involves creating mental space between oneself and the emotional event in order to see things from a different, less self-focused perspective. It has been shown that distancing is a strategy that people can improve at over time compared to reinterpretation. The neural systems which support the explicit regulation of emotion have previously been characterized and include both lateral- and prefrontal cortex. This frontal activity is predicted to downregulate limbic circuitry involving the amygdala during passive viewing of emotional salient stimuli.