This post was written by Kübra Fethiye Karataş, MSc, with edits from Jo Cutler, Ph.D.
At the heart of motivation is a simple question: How much effort are we willing to put in for a reward? It can be measured by how much energy we are prepared to exert to get something in return.
But what happens when the reward isn’t for us, but for another person?
Humans often go out of their way to help others, such as carrying a friend’s furniture, volunteering time, or offering a lift home. These prosocial behaviours are acts that benefit another person, and they’re essential for holding communities together. But they can also be demanding, costing time, energy, and effort.
What’s happening in the brain when we decide to help?
We know a lot about why people work for their own rewards, but much less about why they sometimes put in the same effort when the reward goes to someone else. Previous research in both animals and humans has shown that boosting dopamine can increase the willingness to choose to exert effort to obtain rewards for ourselves. Yet often we must choose whether to exert effort, not for our own immediate benefit, but to be prosocial and obtain a benefit for someone else. What we don’t yet fully understand is whether the same brain chemical that fuels our personal motivation also makes us more willing to help others. Could dopamine be the push we need to put in effort for someone else’s benefit?
Testing the role of dopamine in motivation in Parkinson’s disease
To find out, Talbot and colleagues (2025) turned to people with Parkinson’s disease because many take dopamine-boosting medication to manage their symptoms, so it created a natural experiment. On one day, Parkinson’s patients took their medication as normal before the experiment (“ON medication”). On another day, the same patients did the same experiment, but delayed their dopamine medication that morning and did the study “OFF medication”.
In the experiment, participants made a series of choices between two options: A “work” offer that was higher in physical effort but obtained a better reward versus a “rest” offer that was equal in duration but involved no physical effort and obtained a worse reward.
In half of the rounds, the Parkinson’s patients decided whether to exert effort to obtain rewards to increase their own bonus payment for the study. During the other half, they were presented with the same offers and could exert the same effort, but were informed that rewards earned would be delivered to an anonymous person instead of themselves. This established paradigm, known as the prosocial effort task (Lockwood et al., 2017), is designed to measure how willing people are to work for themselves as opposed to others.
Using this task, Talbot and colleagues (2025) tested whether lower dopamine levels in Parkinson’s disease or boosting dopamine with medication changed how willing people were to put in effort for rewards that benefited themselves or an anonymous other person.
Dopamine boosts motivation to help others
When Parkinson’s disease patients were off their medication, they were less likely to choose the harder “work” option when the reward was for someone else than when rewards were for themselves. This is known as a “self-bias” and is common in healthy participants as well as the patients in this study. However, when the patients were on their dopamine-boosting medication, they were less biased. With dopamine in their system boosted, the patients were relatively more helpful towards the anonymous other person.
The amount of physical effort needed in the experiment stayed the same across conditions, eliminating the possibility that the change in their behaviour was due to differences in difficulty. Instead, the results of the experiment suggest that dopamine levels may play a role in how willing people are to put in effort to benefit others as well as themselves.
Conclusion
Helping others often requires time and effort, and the decision to do so can depend on many factors, from personal values to social context. The findings from this recent study suggest that brain chemistry, and dopamine in particular, may also play a role in how much effort people are willing to put in for someone else’s benefit.
Understanding the biological mechanisms could help researchers get a better picture of why people differ in their willingness to help, and how this might change in different contexts. While medication is not a shortcut to boosting kindness, similar studies carry the potential to provide valuable clues about the interplay between brain chemistry and our social world. The results from this study provided the first insight into the neurochemicals underlying prosocial effort and also highlight dopamine as a key to working hard to help others.
