Skip to main content
European Commission logo print header

Joint action expertise: Behavioral, cognitive, and neural mechanisms for joint action learning

Final Report Summary - JAXPERTISE (Joint action expertise: Behavioral, cognitive, and neural mechanisms for joint action learning)

From playing piano duets to dancing tango to moving furniture together, humans have the amazing ability to coordinate their actions with each other to achieve joint goals. The aim of the JAXPERTISE Project was to investigate what it takes to perform skilled joint actions, and what people learn by participating in and by observing joint actions. In order to do so, the JAXPERTISE team, comprised of PhD students and post-doctoral researchers from several different countries and continents, asked participants in the lab to perform many different joint actions under various different conditions. To give a few examples, participants made music together, played coordination games with their hands, or walked in synchrony next to each other. They watched as others demonstrated how to play a melody, improvised movements together in a joint performance, or gestured at each other. Using a range of different methods, we measured brain activity through electroencephalography; we studied action performance through motion tracking, video, and reaction times; we tested participants' memory for information that had been encountered in different contexts; and we measured through reaction time tests and questionnaires how people's attitudes towards others changed depending on the interactions they had.

One key finding of the project was that when planning joint actions, individuals plan not only their own contributions, but form representations of joint outcomes that specify relations between their own and their partner's contributions. We also found compelling evidence that when individuals need to decide between different courses of action, they consider not only their own costs or only their partner's costs, but act in a way that minimizes joint effort. The conclusion that can be taken away from this is that people think as "we" when acting together.

Second, the project showed the importance and the limitations of predicting others' actions. On the one hand, predicting the actions of task partners ahead of time can tremendously facilitate coordination. On the other hand, predicting the timing of others' actions is far from easy and joint action partners often resort to more simple strategies, such as trying to act in a stable and consistent manner.

The project also led to new insights into how joint actions are perceived and how joint action observation supports learning. For example, we showed that children are able to perceive relations between actions and imitate these at the age of 4-5 years; that people have a tendency to perceive interacting individuals in a holistic way; and that observers can identify expertise in coordination, which is accompanied by distinct aesthetic experiences.
Finally, the project made progress in understanding the role of perspective taking in joint action, showing benefits of interacting with multiple partners through increased perspective taking, and detrimental effects of perspective taking (i.e. thinking too much about a task partner) when coordination could only be achieved by focusing on perceptual features of the environment.

Overall, the findings draw attention to the importance of non-verbal processes in social interaction and highlight the need to understand not only people's motivation to cooperate, but the mechanisms allowing them to achieve cooperative goals together. This has implications for Philosophy of Action, Social Psychology and Social Cognition. The findings also have implications for memory research and for research on communication. Many of the findings are of direct relevance to the quickly growing field of human-robot interaction, which tries to learn from interactions between humans to improve the design of collaborative robots. Some of the findings will also help design interventions aimed at improving inter-group relations.