Negativity bias

Negativity bias is the name for a psychological phenomenon by which humans pay more attention to and give more weight to negative than positive experiences. This shows up in a number of domains, including:
 * People will work harder to avoid losing an amount of money than they will to gain the same amount of money. When we compare how strongly people rate their emotions when losing vs. gaining the money, the people who lost money have a stronger reaction. This phenomenon has been researched in the field of economic psychology as part of prospect theory.
 * When given a piece of positive information and a piece of negative information about a stranger, people's judgment of the stranger will be negative, rather than neutral (assuming the two pieces of information are not severely imbalanced).
 * If a person has a good experience and a bad experience close together, they will feel worse than neutral. This is true even if they would independently judge the two experiences to be of similar magnitude.
 * When put in an environment with a variety of information to pay attention to, people will immediately notice the threats instead of the opportunities or the signals of safety. Evolutionary psychology sees this as an example of a smoke detector system.

The definitive publication on negativity bias in the field of psychology is by Roy Baumeister, Ellen Bratslavsky, Catrin Finkenauer, and Kathleen Vohs and the phenomenon is often referred to by the paper's title: Bad is Stronger than Good. Prospect theory, developed by Kahneman and Tversky, is an older and independent area of research that produces many of the same results.

Is Bad Stronger than Good?
A more apt description of the theory is that bad is more attention-getting than good. Positive events exert effects in other ways:
 * Most people feel mildly positive, most of the time. This suggests that negative events that are sufficiently strong to exert the "bad is stronger" effect may not be that common (see positivity offset).
 * Positive events can aid recovery from the cardiovascular wear and tear caused by the stress response to negative events. This is referred to as the undo effect of positive emotions.
 * When positive emotions are experienced regularly, over time, they can have cumulative benefits that are more substantial than the effects of negative emotions. This is referred to as the broaden-and-build effect.
 * As people age, the negativity bias is reduced and may even disappear. It is presently unclear exactly what about aging causes this positivity effect.

Nonetheless, when assessing an immediate situation, it does seem that negative information and negative events predominate, and this has significant implications for everything from aesthetics to trauma recovery to the study of stress and biochemistry.