Encouraging two parts of the brain to fire in sync can make people act more generously, according to research published February 10th in the open-access journal PLOS Biology. The study was led by Jie Hu of East China Normal University in China, in collaboration with researchers from the University of Zurich in Switzerland. By aligning activity between specific brain regions, the team found they could slightly increase altruistic behavior.
Parents often try to teach their children to share, show kindness, and think about the needs of others. These traits help communities function smoothly. Still, adults differ widely in how selfless they become. Some consistently put others first, while others remain more focused on personal gain. Scientists have long wondered what drives these individual differences.
The Dictator Game and Brain Stimulation
To investigate, the researchers recruited 44 participants and asked them to make 540 decisions in a Dictator Game — offering to split an amount of money with someone else, which they then got to keep. In each round, the payout amounts changed, and participants could end up with either more or less money than their partner.
During the task, the team applied transcranial alternating current stimulation to the frontal and parietal lobes. This noninvasive technique was designed to coordinate the firing patterns of neurons in those areas. The stimulation guided the brain cells to align in repeating rhythms, either gamma or alpha oscillations.
Gamma Synchrony Increased Generous Choices
When the stimulation specifically strengthened gamma synchrony between the frontal and parietal regions, participants showed a modest increase in altruistic decisions. They were more likely to share larger amounts of money, even when doing so reduced their own earnings compared to their partner.
Using a computational model, the researchers found that the stimulation shifted how participants evaluated each offer. After stimulation, individuals placed greater weight on the other person’s outcome when deciding how to divide the money. The authors emphasize that they did not directly measure neural activity during the experiment. Future research combining brain stimulation with electroencephalography could confirm how the intervention changes brain signals. Even so, the findings suggest that synchronized activity between the frontal and parietal lobes plays a role in altruistic decision making.
Researchers Highlight Cause and Effect
Coauthor Christian Ruff states, “We identified a pattern of communication between brain regions that is tied to altruistic choices. This improves our basic understanding of how the brain supports social decisions, and it sets the stage for future research on cooperation — especially in situations where success depends on people working together.”
Coauthor Jie Hu notes, “What’s new here is evidence of cause and effect: when we altered communication in a specific brain network using targeted, non-invasive stimulation, people’s sharing decisions changed in a consistent way — shifting how they balanced their own interests against others’.”
Coauthor Marius Moisa concludes, “We were struck by how boosting coordination between two brain areas led to more altruistic choices. When we increased synchrony between frontal and parietal regions, participants were more likely to help others, even when it came at a personal cost.”