Anyone who has ever danced a tango, cooked with a friend, or mixed a cocktail in tandem knows the difference: acting together is not the same as simply moving next to someone. It requires coordination, shared intention, and trust—elements that are central to our everyday social life.

Yet, despite how fundamental this distinction is to human interaction, cognitive neuroscience has largely overlooked it. A new Italian study, published in Social Cognitive and Affective Neuroscience, has now taken a closer look at the brain mechanisms that set true joint action apart from parallel activity.

The research was led by Corrado Sinigaglia, head of the Cognition in Action Lab (PHILAB) at the University of Milan, and Marta Bortoletto from the IMT School for Advanced Studies Lucca, in collaboration with Sapienza University of Rome and the St. John of God Clinical Research Center in Brescia.

For the first time, the team investigated the distinct neural dynamics behind acting with a shared goal compared to simply acting side by side. Their findings show that when two people pursue a common purpose, the brain engages in different processes than when they merely perform actions in parallel. Joint action, they discovered, comes with an initial cognitive cost. But this effort is later offset by an advantage: in the final stage of the action, coordination is facilitated, likely because the partner’s movements become more predictable.

“These results shed new light on the mechanisms at the core of human sociality and open up promising perspectives for understanding and treating conditions marked by social difficulties, such as autism and schizophrenia,” explains Sinigaglia, corresponding author of the study.

Beyond its clinical implications, the research highlights something profound: teamwork is not just the sum of individual actions. Acting together is a uniquely human ability—one that has shaped the way we connect, cooperate, and evolve.