Encouraging two brain regions to operate in sync to operate in sync may make people behave more generously, according to a study published on February 10 in the open-access journal PLOS Biology. The research was led by Jie Hu of East China Normal University in China, together with colleagues from the University of Zurich. By aligning activity between specific brain regions, the team reports a small but measurable increase in altruistic behavior.
Parents often try to teach children to share, show kindness, and consider other people’s needs—qualities that help communities function. Yet adults differ widely in how selfless they are. Some routinely prioritize others, while some focus more on personal advantage. Researchers have long been interested in what drives these differences.
The Dictator Game and Brain Stimulation
To explore the question, the scientists recruited 44 participants and asked them to complete 540 rounds of a classic “Dictator Game”. In each round, participants decided how to split money between themselves and another person. The amounts changed from round to round, and depending on the choice, a participant could end up with more or less than the other person.
While participants made decisions, the team used transcranial alternating current stimulation (tACS) on areas in the frontal and parietal lobes. The non-invasive method aims to influence the timing of neural activity by nudging brain cells into synchronized rhythms. In this experiment, the stimulation targeted either gamma or alpha oscillations.
Gamma Synchrony Led to More Generous Choices
When the stimulation was set to strengthen gamma synchrony between frontal and parietal regions, participants made slightly more altruistic decisions. They were more likely to give larger shares, including in situations where sharing meant they would end up with less money than the other person.
Using a computational model, the researchers concluded that the stimulation changed how participants weighed outcomes. After gamma synchrony stimulation, people placed more weight on the other person’s payoff when deciding how to divide the money.
The authors note that they did not directly record neural activity during the task. They suggest that future work combining stimulation with electroencephalography (EEG) could help confirm how the intervention alters brain signals. Even so, the results point to coordinated activity between the frontal and parietal lobes as an important factor in altruistic decision-making.
Researchers Emphasize a Cause-and-Effect Link
Co-author Christian Ruff said the team identified a communication pattern between brain regions associated with altruistic choices, improving understanding of how the brain supports social decisions and providing a basis for future research on cooperation—especially in settings where success depends on people working together.
Co-author Jie Hu highlighted what the team sees as evidence of causality: changing communication within a specific brain network using targeted, non-invasive stimulation produced consistent shifts in sharing decisions, affecting how people balanced their own interests against those of others.
Co-author Marius Moisa added that the researchers were struck by how increasing coordination between the two areas led to more altruistic choices, even when helping others came at a personal cost.
