Shared mental models are the understandings people hold in common about how something works, what matters and how they should act together.
They help people coordinate without having to explain everything from the beginning each time. A team may share an understanding of its purpose, roles, priorities, risks and how decisions will be made.
Shared does not mean identical or unquestioned. Healthy shared mental models make differences easier to discuss and change when experience shows that the group’s understanding is incomplete or wrong.