Current Man Machine Interfaces (MMI) present information to the operator when it becomes available and when it is convenient to the computer; such automated systems do not act as a 'team player'. Computers lack insight in the actual status, intentions and occupations of the operator. An approach is presented ( COMPANION) in which better co-operation between user and computer is stimulated. In this approach, information about the users' ( physiological) state is used to adapt the MMI of the task at moments or in time periods where this is helpful for optimal task performance. Also task performance measures can be used in this feedback structure. COMPANION is about improving the Human Machine relation by: not interrupting the operator with non-urgent messages when he or she is completing an important task, and supporting the operator when task demands are high. In order to prevent specific solutions for each new task or for each additional information source an Operator Status Model (OSM) has been developed.