Vehicle Occupant Safety System with Variable Support and Method of Operating the Same

A vehicle occupant safety system having an airbag prevents an excessive force from acting upon the thorax of an occupant who has fastened the seat belt, in the event of an impact. The vehicle occupant safety system comprises an airbag, a sensor device for sensing at least one situation parameter and a control device for controlling the inflation and/or deflation and/or unfolding and/or positioning of the airbag in dependence of the at least one situation parameter. The unfolding, position or shape of the airbag and/or distribution of pressure within the airbag at the end of the filling phase, is directly or indirectly controlled in a targeted manner by a control device based on the at least one situation parameter. A modification of the shape of the airbag in the thorax region can be obtained in particular by a releasable constriction.