Negative affect decreases judgmental bias

Attention pro-positive affect believers: Negative affect has significant beneficial impacts on cognition and behavior. Benefits include improved perception, judgment, memory, and interpersonal personal relations.

Negative affect induces more on cautious processing than preexisting knowledge, so people with negative affect perform better in instances involving deception, manipulation, impression formation, and stereotyping. Also, negative affectivity’s tendency for analytical and detailed processing leads to fewer reconstructive-memory errors. Information processing in negative moods reduces the misinformation effect and increases accuracy of recalled details.

Judgment

Judgmental accuracy is improved in areas such as impression formation, reducing fundamental attribution error, stereotyping, and gullibility.

Impression formation

Negative affect is shown to decrease errors in forming impressions based on presuppositions.

A study involving undergraduate students demonstrated a halo effect in identifying a middle-aged man as more likely to be a philosopher than an unconventional, young woman. These halo effects were nearly eliminated when participants were in a negative affective state:

2011

Negative affect eliminates the halo effect

Forgas, Joseph P. (2011). She just doesn't look like a philosopher...? Affective influences on the halo effect in impression formation.

Fundamental attribution error

The systematic, attentive stance produced by negative affect reduces fundamental attribution error (FAE)—the tendency to inaccurately attribute behavior to a person’s internal character while ignoring external contributing factors. How? FAE occurs when people use top-down cognitive processing based on inferences, while negative affect stimulates bottom-up, systematic analysis that reduces fundamental attribution error.

In this study, participants read one of two possible essays arguing for one side or another on a highly controversial topic. Participants were informed that the stance taken by the debater was assigned and did not necessarily reflect his views. Still, the positive affect groups said the debaters who argued unpopular views actually held their affected attitudes and rated them as unlikeable compared to debaters with popular stances. In contrast, the data for the negative affect group displayed no significant difference in ratings for debaters with popular stance and debaters with unpopular stances:

1998

Negative affect reduces dispositional attributions based on coerced essays advocating unpopular opinions

Forgas, Joseph P. (1998). On being happy and mistaken: mood effects on the fundamental attribution error.

Stereotyping

Negative affect benefits judgment promoting closer attention to stimuli, thus diminishing reliance on stereotypes.

In this study, participants were less likely to discriminate against targets that appeared Muslim when in a negative affective state. From Wikipedia:

After organizing participants into positive and negative affect groups, researchers had them play a computer game. Participants had to make rapid decisions to shoot only at targets carrying a gun. Some of the targets wore turbans making them appear Muslim. As expected, there was a significant bias against Muslim targets resulting in a tendency to shoot at them. However, this tendency decreased with subjects in negative affective states. Positive affect groups developed more aggressive tendencies toward Muslims. Researchers concluded that negative affect leads to less reliance on internal stereotypes, thus decreasing judgmental bias.

2013

Negative affect decreases judgmental bias

Forgas, Joseph P. (2013). Don’t Worry, Be Sad! On the Cognitive, Motivational, and Interpersonal Benefits of Negative Mood.