On the importance of flow direction in business process models

In today´s modeling practice we can observe a convention to model business processes from left-to-right or from top-to-bottom. Even though the choice of flow direction changes the visual appearance of a process model significantly, this convention is barely discussed by standard documents and modeling guidelines. In addition, most recommendations related to the flow direction are neither based on scientific claims nor on empirical evidence regarding their effectiveness in terms of readability. In this position paper, we discuss the importance of process model flow direction from a scientific viewpoint. In particular, we give a comprehensive overview of theoretical perspectives which offer explanations why a left-to-right flow direction for process models should be superior to other directions.