At the end of each semester I dutifully hand out course evaluations to my classes and wait: until these evaluations are coded up by the powers-that-be and then sent back to me. I look forward to seeing what students thought of the class, but inevitably my reaction to their comments is determined, not by the average of students' sentiments, but by the comments of the most negative student. Even in a large class, with 100s of students, which average out to a fairly rosy evaluation, my sense of satisfaction is driven more by that one cranky, negative comment rather than the vast majority of the more positive ones. The bad evaluation crushes the good ones.

Baumeister and his colleagues, in their provocatively entitled paper "Bad is Stronger than Good," draw on research in a wide psychological topics to marshall support for their basic idea that negative information and negative processes overwhelm positive information and positive processes.

One particularly straightforward way to demonstrate their thesis is to ask people to make judgments of people described with a cluster of positive and negative attitudes. Some of the adjectives have been shown, in advance, to be positive ones: on a scale from 0 to +3, easygoing is a 1.1, direct is a 1.0, and loyal a 2.5. If a person has all these qualities, they should be rated pretty positively.

Other adjectives, though, are more negative ones: insincere, for example, is a -2.3, and malicious -2.5. The person who is insincere, malicious, obnoxious and cruel should get a pretty low rating.

But what happens when a person is described with a positive and a negative adjective? Will the positive one's overwhelm the more negative ones? As Baumeister's work suggests, bad is stronger than good. Someone who is unkind (-2.3) and mean (-2.5) but also loyal (+2.5) and sincere (+2.5) is not viewed neutrally, which would be the case if the bad was equal to the good. Instead, they are rated negatively. In fact, just a single negative quality, such as cruel (-2.5) is sufficient to drag down the positive evaluation created by 3 highly positive qualities (sincere, honest, and loyal).

Riskey and Birnbaum verified this tendency nicely by first giving people one single bit of information about a person's behavior. That behavior was a highly negative one (Secretly spiking a party's potato chips with a dangerous drug), a somewhat negative one (cheating on a test), a somewhat positive action (fixing a friend's car), or a highly positive (saving someone's life). They then added more information about the person--all positive or highly positive information that suggested the person was a very good individual. Yet, they found that individuals who performed just one negative behavior were never positively evaluated, even after 9 positive actions to the list. Only the person who performed a mildly bad action eventually climbed in to the morally good category. Their results are shown below.