Why we are quick to blame, slow to credit

A new study has helped explain the paradox of why we are quick to blame people for their actions, but slower to give them credit.

We constantly read others' intentions in what they do, from seeing someone help an elderly person cross the street or cutting in line or committing a heinous crime. Judgments about intentionality are threaded deeply within our legal system and pervasive in our support of political candidates, and have been the focus of discussion for the past decade in the philosophical literature.

The Duke University study is the first to use neuroscience research tools to try to explain why people are biased toward treating negative actions as intentional but positive actions as unintentional, said lead author Lawrence Ngo.

"There's no logical reason why we would call something intentional, just because it causes a bad outcome as opposed to a good outcome," said corresponding author Scott Huettel, adding "Intentionality implies purpose on the part of the person, and that should be there for good as much as it is for bad. But it's not.

To understand why, Huettel's team assessed differences in personality traits and other psychological measures. Using functional magnetic resonance imaging, a type of non-invasive brain scan, the researchers also analyzed activity of individuals' brains while they read the scenarios.

The team found that people use two different mechanisms to judge how intentional an action was. If the action produced a negative effect, participants were more likely to draw on brain areas involved in processing emotion (in particular, the amygdala, a pair of almond-shaped structures deep in the brain that is well known for its role in processing negative emotions).

The greater the emotional reaction the participant reported having to a particular story, the stronger it activated their amygdala. But if an action produced a positive effect, it was less likely to set off the amygdala.

On the other hand, for positive outcomes people relied less on emotion and more on statistics. That is, they thought about how often people in a particular situation would behave in a similar way.

Duke researchers are already making strides toward bridging these disparate fields. Huettel and his collaborators are planning new studies on trust, deception and altruism.

The study appears in Scientific Reports.