"The greater power of bad events over good ones is found in everyday events, major life events, close relationship outcomes, social network patterns, interpersonal interactions, and learning processees. Bad emotions, bad parents, and bad feedback have more impact than good ones, and bad information is processed more thoroughly than good. The self is more motivated to avoid bad self-definitions than to pursue good ones. Bad impressions and bad stereotypes are quicker to form and more resistant to disconfirmation than good ones. Various explanations such as diagnosticity and salience help explain some findings, but the greater power of bad events is still found when such variables are controlled. Hardly any exceptions (indicating greater power of good) can be found. Taken together, these findings suggest that bad is stronger than good, as a general principle across a broad range of psychological phenomena..."
-Baumeister, Bratslavsky, Finkenauer, and Vohs in Review of General Psychiatry, Vol.5 No.4 2001