It is common to deal sternly with people who actively commit harm than those who passively involved. However a conscious rationale is vital to regard active and passive behaviours as equally condemnable, in cases where the outcome of the harm is of the same intensity, opine researchers.
People typically say they are invoking an ethical principle when they judge acts that cause harm more harshly than willful inaction that allows that same harm to occur. That difference is even codified in criminal law.
A new study based on brain scans, however, shows that people make that moral distinction automatically.
Fiery Cushman employed behavioural experiments, online surveys, and functional magnetic resonance imaging to figure out how the brain has evolved to process moral dilemmas and make moral judgments.
"What it looks like is when you see somebody actively harm another person that triggers a strong automatic response," said Brown University psychologist Fiery Cushman.
"You don't have to think very deliberatively about it. You just perceive it as morally wrong. When a person allows harm that they could easily prevent, that actually requires more carefully controlled deliberative thinking [to view as wrong]."
In a study Cushman and his co-authors presented 35 volunteers with 24 moral dilemmas and lapses. For specific lengths of time the volunteers would read an introduction to the incident, a description of the character's moral choices, and a description of how the character behaved.
Then they rated the moral wrongness of the behaviour on a scale from 1 to 5. All the while, Cushman and his co-authors tracked the blood flow in the volunteers' brains with functional magnetic resonance imaging scans.
Cushman expected to confirm what he had observed in behavioural experiments and published in 2006: that people employed conscious reasoning to arrive at the usual feeling, which is that actively caused harm is morally worse than the passively caused harm.
Figuring he had a clever way to prove it physiologically, he and his team compared the brain scans of people who judged active harm to be worse than passive harm to the scans of people who judged them as morally equal.
His assumption was that those who saw a moral difference did so by explicit reasoning. Such people should therefore have exhibited greater activity in the dorsolateral prefrontal cortex than those who saw no moral distinction.
But to Cushman's surprise, the greater levels of DPFC activity lay with those who saw active harm and passive harm as morally the same.
"The people who are showing this distinction are actually the ones who show the least evidence of deliberative, careful, controlled thinking."
"whereas the people who show no difference between actions and omissions show the most evidence of careful deliberative controlled thinking," he added.
The study has been published in advance online in the journal Social Cognitive and Affective Neuroscience.