Humans are less concerned about the inequity of others, according to a recent study.

Researchers from Georgia State University found that strongly influenced by their self-interest, humans do not protest being overcompensated, even when there are no consequences. This could imply that humans are more interested in their own outcomes than those of others.

"A true sense of fairness means that I get upset if I get paid more than you because I don't think that's fair," researcher Sarah Brosnan said in a statement. "We thought that people would protest quite a bit in the fixed decision game because it's a cost-free way to say, 'This isn't fair.' But that's not what we saw at all. People protested higher offers at roughly the same rate that they refused offers where they got more, indicating that this lack of refusal in advantaged situations may not be because of the cost of refusing. It may just be because people don't care as much as we thought they did if they're getting more than someone else."

The researchers also used functional magnetic resonance imaging (fMRI) to study the underlying brain mechanisms from 18 participants, who played three two-person economic exchange games that involved inequity in their favor and not in their favor. Overcompensated offers triggered a different brain circuit than undercompensated offers and indicate that people may be responding to overcompensation as if it were a reward. This could explain the lack of refusals in this unfair situation, researchers said.

The results of brain response provided new insights into the functional role of the dorsolateral prefrontal cortex and related networks of brain regions for advantageous inequity and protest.

The findings were recently published in the journal Brain Connectivity.