For many, making a relatively simple decision ends up being a source of stress. The story is familiar to all of us: We are renovating and choosing paint colors. After agonizing over color charts and asking the opinion of everyone in our lives, we finally decide on one and give the painter the go-ahead. But even as he is throwing the color up on the wall, we wonder if we should have chosen a lighter or deeper shade.

Why are some of us so uncertain while others know exactly what they want? For such value-based choices, organisms must flexibly integrate various types of sensory information about internal states and the environment to transform them into actions. Now, a new study in Nature Communications shows which areas of the brain are most active in this decision-making process.

In this study, headed by Professor Christian Ruff, a neuroeconomist from the University of Zurich, researchers demonstrate that the intensity of communication between different regions of the brain dictates whether a person is decisive or indecisive. The more intensive the information flow, the more decisive a person is.

The researchers found the precision and stability of preference decisions do not simply depend on the strength of the activation of one or more brain regions. Instead, the key for stable preference choices is the intensity of the communication between two areas of the brain that represent our preferences or are involved in spatial orientation and action planning.

The researchers used transcranial alternating current stimulation, a noninvasive brain stimulation method that enables generation of coordinated oscillations in the activity of particular brain regions. The study participants did not even realize they were being stimulated.

Using this technique, the researchers intensified or reduced the information flow between the prefrontal cortex located directly below the forehead and the parietal cortex just above both ears. The participants were asked to make choices about food based on preferences or purely sensory input.

The researchers discovered that preference-based decisions were less stable if the information flow between the two brain regions was disrupted. So, participants were more indecisive. For the purely sensory decisions, however, there was no such effect.

Consequently, the communication between the two brain regions is only relevant if we have to decide whether we like something, not when we make decisions based on objective facts.

It was not possible to make the decisions more stable by intensifying the information flow. However, the study participants were young and healthy with highly developed decision-making skills.

According to the researchers, the results of the study could be used for therapeutic measures in the future, such as in patients who suffer from a high degree of impulsiveness and indecisiveness in the aftermath of brain disorders.