How Your Brain Makes Utilitarian Decisions

How do you make a choice that will benefit the greatest number of people when there are conflicting preferences involved? How does the brain make sense of differing perspectives and organize them to make a decision? In a study recently published in JNeurosci, researchers from Ludwig Maximilian University and the University of Zurich explore the neural intricacies of utilitarian welfare decisions. By investigating the role of the ventromedial prefrontal cortex through food preference and decision tasks, the study unveils how our brains navigate complex social choices, offering crucial insights into the neural basis of utilitarian decision-making.

What is utilitarian welfare?

Utilitarian welfare is a concept in welfare economics that defines social welfare as the well-being of all members of society. It is based on the moral philosophy of utilitarianism, which states that the right course of action is the one that maximizes overall happiness or well-being for the greatest number of people.

Utilitarianism treats all individuals equally and does not differentiate between a poor person and a rich person. It differs from other welfare concepts like the Rawlsian approach, which focuses on maximizing the well-being of the worst-off members of society.

Utilitarian welfare decision-making is a framework that is used in various contexts where the goal is to maximize overall well-being or utility for the greatest number of people. Public policy is an example where governments attempt to make decisions that will maximize the overall welfare of society, with healthcare, education, infrastructure, and social welfare decisions affecting the population as a whole. Environmental conservation is an example that requires balancing competing interests to achieve the greatest overall benefit for ecosystems and species, both now and in the long term.

On a smaller, individual scale, we make utilitarian welfare decisions daily. Choosing how we spend our time and money, we take into account various factors in an attempt to decide with the greatest benefit. Charitable donations, personal finance, consumer choices, and personal health decisions usually aim to maximize overall well-being, whether for ourselves, our communities, or broader society.

How do we make decisions?

Humans make decisions using a variety of different brain regions. The prefrontal cortex plays a crucial role in decision-making by integrating information, evaluating options, and selecting the appropriate course of action. It determines the additional information required and retrieves it from the hippocampus.

The hippocampus is involved in storing and retrieving memories and knowledge relevant to the decision-making process. It provides initial information to the prefrontal cortex based on sensory inputs and past experiences.

The amygdala is associated with processing emotions and is believed to contribute to decision-making, especially in situations that involve risk, reward, and emotional valence. It interacts with the prefrontal cortex and other regions to influence decision outcomes.

Utilitarian welfare in the brain

How the brain regions responsible for processing rewards can accurately represent and combine different preferences from different individuals is not well understood. A recent study conducted by a team of researchers from the Department of Psychology at Ludwig Maximilian University in Munich, Germany, and the Department of Economics in Zurich, Switzerland, and published in JNeurosci, looks at how the brain implements welfare decisions when others’ preferences conflict.

In their study, 46 participants were presented with food items and asked to indicate how much they liked each of them. A pair of food items is chosen for each participant with the preferred food labeled ‘A’ and the less preferred food labeled ‘B’ and randomly assigned a color (blue or red). The participants learn which color is associated with each food item before progressing to the decision tasks inside the magnetic resonance imaging scanner.

The first task is an individual task where participants choose their preference between different quantities of A and B, depicted by the number of blue or red squares. In the preference learning task, participants predict the choices of two other participants, or agents. If the prediction is correct, +10 appears whereas if the prediction is wrong, -10 appears. The two agents have opposing preferences between food A and B and the participant performs 312 trials, learning the preferences of the two agents.

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Lastly, the participants participate in a welfare maximization task, making choices that assign different quantities of A and B to the two agents. An example of a choice is, “1A for agent 1, 5B for agent 2 versus 5A for agent 1, 1B for agent 2.” There is no incentive for participants in this task and they receive no specific instructions for how to make choices. To maximize utilitarian welfare, the participant should choose distributions that are strongly preferred by one agent and only mildly disliked by the other, over distributions that are strongly disliked by one agent and mildly liked by the other, which requires an interpersonal comparison of preference intensities.

The role of the ventromedial prefrontal cortex in decision-making

The results for the first task indicate that the ventromedial prefrontal cortex, located at the bottom of the medial prefrontal cortex, encodes an individual's preferences during individual decision-making, consistent with previous findings. The ventromedial prefrontal cortex interacts with various brain networks, such as the ventral striatum involved with reward processing and the amygdala involved with emotion. Current neuroscientific literature understands the ventromedial prefrontal cortex to be a critical hub that integrates cognitive, affective, and social information to guide decision-making, emotion regulation, and social cognition through its connections with other brain regions.

The second task looks at whether the same neural reward system also encodes the preferences of others. The results indicate that the ventromedial prefrontal cortex encodes the estimated preferences of others, irrespective of the similarity of others’ preferences with one’s own. The ventromedial prefrontal cortex appears to use distinct neural patterns to represent an individual’s preferences compared with those of others. However, it's notable that despite differences in preferences among various individuals, the ventromedial prefrontal cortex employs a consistent neural code to represent the subjective value associated with these preferences. This consistency enables the brain to conduct interpersonal value comparisons effectively.

Implications and future directions

This study offers insights into how humans navigate complex social interactions. By demonstrating that the ventromedial prefrontal cortex plays a central role in representing and comparing the preferences of others, the study highlights the brain’s remarkable ability to integrate diverse perspectives to maximize overall welfare.

These findings have significant implications for both theoretical accounts of moral philosophy and practical decision-making processes. This study challenges the traditional idea that welfare comparisons rely only on ordinal preferences, where preferences are ranked without precise measurement. Instead, it emphasizes the significance of including cardinal utility information, which assigns specific numerical values to preferences, and interpersonal comparisons of utility, which involve comparing the strength or intensity of preferences between individuals. Moreover, the study suggests that utilitarian welfare maximization is enabled by the brain's capacity to compare the preferences of others on a cardinal scale, offering a potential solution to complex decision problems where ordinal preferences alone are insufficient.

Looking ahead, future research could further explore the neural mechanisms underlying utilitarian decision-making, including the role of other brain regions and the influence of additional factors such as emotions and social context. Moreover, investigating how individuals' preferences affect their decisions when distributing welfare among different people and themselves could provide valuable insights into real-world decision-making processes. Overall, this study opens new avenues for understanding how the brain navigates social dilemmas and informs decision-making in diverse contexts.