Influenced by self-interest, humans less concerned about inequity to others

August 21, 2014, Georgia State University
brain
White matter fiber architecture of the brain. Credit: Human Connectome Project.

Strongly influenced by their self-interest, humans do not protest being overcompensated, even when there are no consequences, researchers in Georgia State University's Brains and Behavior Program have found.

This could imply that humans are less concerned than previously believed about the inequity of others, researchers said. Their findings are published in the journal Brain Connectivity. These findings suggest humans' sense of unfairness is affected by their self-interest, indicating the interest humans show in others' outcomes is a recently evolved propensity.

It has long been known that humans show sensitivity when they are at a disadvantage by refusing or protesting outcomes more often when they are offered less money than a social partner. But the research team of physics graduate students Bidhan Lamichhane and Bhim Adhikari and Brains and Behavior faculty Dr. Sarah Brosnan, associate professor of psychology, and Dr. Mukesh Dhamala, associate professor of physics and astronomy, reports that, contrary to expectations, humans do not show any sensitivity when they are overcompensated. They conclude 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," Brosnan said. "We thought that people would 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 (fMRI) to study the underlying 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.

Each game involved three offers for how $100 would be split: fair (amount between $40 to $60), unfair-low (disadvantageous to the subject, amount between $0 to $20) and unfair-overcompensated (advantageous to the subject, amount between $80 to $100). Participants played 30 rounds of each game and earned about two percent of the total amount from the games.

In the first two games, the subject received an offer for how much money they would receive and were then asked whether they wanted to reject or accept it. In the Ultimatum Game, if the responder rejected the offer, neither player received any money, leading to a fair outcome. In the Impunity Game, if the subject rejected the offer, only he or she lost the payoff, meaning the outcome was even more unfair than the offer. The subject got nothing, but the partner still got their proposed amount. In the Fixed Decision Game, the subject could choose to protest or not protest the offers, but this didn't change the outcome for either player. This allowed subjects to protest offers without an associated cost.

The blood-oxygen level dependent signals of the brain were recorded by an MRI scanner as participants played the games. The results of brain response provided new insights into the functional role of the and related networks of brain regions for advantageous inequity and protest.

A network of brain regions consisting of the left caudate, right cingulate and right thalamus had a higher level of activity for overcompensated offers than for fair offers. For protest, a different network, consisting of the right dorsolateral prefrontal cortex, left ventrolateral prefrontal cortex and left substantia nigra, came into play. The researchers also mapped out how the brain activity flow occurred within these networks during decision-making.

Explore further: Self-centered kids? Blame their immature brains

More information: The study, "The Neural Basis of Perceived Unfairness in Economic Exchanges," is available online at online.liebertpub.com/doi/abs/ … 1089/brain.2014.0243

Related Stories

Self-centered kids? Blame their immature brains

March 7, 2012
A new study suggests that age-associated improvements in the ability to consider the preferences of others are linked with maturation of a brain region involved in self control. The findings, published by Cell Press in the ...

Why antisocial youths are less able to take the perspective of others

March 11, 2014
Adolescents with antisocial personality disorder inflict serious physical and psychological harm on both themselves and others. However, little is yet known about the underlying neural processes. Researchers at the University ...

Sense of justice built into the brain

May 3, 2011
A new study from the Karolinska Institute and Stockholm School of Economics shows that the brain has built-in mechanisms that trigger an automatic reaction to someone who refuses to share. In the study publishing next week ...

Kirk, Spock together: Putting emotion, logic into computational words

March 5, 2013
Kirk and Spock may not need a Vulcan mind meld to share cognition: Virginia Tech Carilion Research Institute scientists have found that our cold reasoning and hot feelings may be more intimately connected than previously ...

Study reveals human drive for fair play

August 23, 2012
People will reject an offer of water, even when they are severely thirsty, if they perceive the offer to be unfair, according to a new study funded by the Wellcome Trust. The findings have important implications for understanding ...

Recommended for you

Research reveals atomic-level changes in ALS-linked protein

January 18, 2018
For the first time, researchers have described atom-by-atom changes in a family of proteins linked to amyotrophic lateral sclerosis (ALS), a group of brain disorders known as frontotemporal dementia and degenerative diseases ...

Fragile X finding shows normal neurons that interact poorly

January 18, 2018
Neurons in mice afflicted with the genetic defect that causes Fragile X syndrome (FXS) appear similar to those in healthy mice, but these neurons fail to interact normally, resulting in the long-known cognitive impairments, ...

How your brain remembers what you had for dinner last night

January 17, 2018
Confirming earlier computational models, researchers at University of California San Diego and UC San Diego School of Medicine, with colleagues in Arizona and Louisiana, report that episodic memories are encoded in the hippocampus ...

Recording a thought's fleeting trip through the brain

January 17, 2018
University of California, Berkeley neuroscientists have tracked the progress of a thought through the brain, showing clearly how the prefrontal cortex at the front of the brain coordinates activity to help us act in response ...

Midbrain 'start neurons' control whether we walk or run

January 17, 2018
Locomotion comprises the most fundamental movements we perform. It is a complex sequence from initiating the first step, to stopping when we reach our goal. At the same time, locomotion is executed at different speeds to ...

Neuroscientists suggest a model for how we gain volitional control of what we hold in our minds

January 16, 2018
Working memory is a sort of "mental sketchpad" that allows you to accomplish everyday tasks such as calling in your hungry family's takeout order and finding the bathroom you were just told "will be the third door on the ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

RobertKarlStonjek
1 / 5 (1) Aug 21, 2014
This sounds very much like the behaviour of American college students.

Hardly surprising, then, to find that this the cohort being tested. The results apply only to American college students playing games and should not be generalised beyond that very narrow study.

People mature after leaving college. Americans are known to be more individualistic and self centred than people in other modern western countries. And game theory, when tested on tribal people who had little contact with the west and no experience playing games of any kind responded completely differently to games like the Ultimatum game when tested a few years ago.

See the paper:
'Economic Man' in Cross-cultural Perspective: Behavioral Experiments in 15 Small-scale Societies
http://www.sscnet...inal.pdf

"We found, first, that the canonical selfishness-based model fails in all of the societies studied."

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.