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A new study has found that when two people engage in a shared task, their brains begin to process information in strikingly similar ways.

Collaboration underpins essential human activities—from farming to childcare—and relies on people perceiving situations in the same way and following mutually agreed rules. For instance, partners must jointly recognise which fruits are ripe and which should remain untouched.

The study, published in the open-access journal PLOS Biology, was conducted by Denise Moerel and colleagues at Western Sydney University, Australia.

To investigate how partners think during cooperative tasks, the researchers recruited 24 pairs. Each duo first agreed on how to categorise various shapes—based on lines, thickness, contrast, or general form. After establishing their strategy, they sat back-to-back and categorised a series of patterns together while electroencephalogram (EEG) recordings tracked how closely their brain activity aligned.

In the initial 45–180 milliseconds after a shape appeared, all participants showed similar neural responses simply because they were viewing the same image. However, after around 200 milliseconds—when they began applying their jointly chosen rules—brain activity became synchronised only within pairs who were actually collaborating.

As the experiment progressed, each pair’s neural activity became more aligned, reflecting their growing cohesion and shared understanding.

The findings reveal that when people coordinate and agree on rules, their brains adapt to process information alike. According to the authors, this alignment may help explain how groups build shared decision-making processes, traditions, and collective behaviours.

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“As two people learn to work together, their brains start to represent information in more similar ways, demonstrating that collaboration shapes how we perceive and interpret the world,” the researchers noted.