Human success depends on collaboration and communication, our ability to listen and come to a shared understanding.

To find out what happens in our brains when we come to consensus, we designed an experiment to catch consensus-building across brains in action. We discovered two remarkable phenomena.

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EXPERIMENT

We scanned participants' brains while they watched silent movie clips they had never seen before. Then participants split into groups. Each group was asked to reach consensus on the meaning of the movie clips. After this conversation, we scanned participants' brains again while they watched the movie clips a second time, along with new clips from the same movies.

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RESULT #1

Through this experiment, we saw that members of the same group had the same brain activity at the same time in brain areas for vision, memory, and social understanding. By talking together and coming to consensus as a group, participants aligned their brains. Remarkably this alignment extended to new movie clips the groups did not discuss. Through consensus, each group shared a way of seeing the world.

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RESULT #2

But not every participant helped build consensus the same way. Participants who were central in their social networks kept the conversation flowing and changed their brain activity to match the group, creating alignment. By contrast, participants that were rated as having high social status dominated the conversation, preventing alignment.

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KEY TAKEAWAYS

This experiment shows how talking can change thinking. We use language to steer others' thoughts and, importantly, to let others steer us.

To face our hardest challenges, we need to unite around our common goals. Conversation may be humanity's greatest tool for changing our minds and aligning our brains.