Changing Interaction Dynamics in Hierarchical Groups: Evidence from a Role Expansion Field Experiment in Healthcare

*Authors contributed equally and are listed in alphabetic order. We wish to express our appreciation to the staff and leadership of the healthcare centers in which we conducted this research. This work would not have been possible without their welcoming us to study their role change experience and embracing the idea of wearing sensors. We gratefully acknowledge Paul D. Cleary and Yuna Lee for their partnership in the design of this study, and Dava Flowers-The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding agency. 2 ABSTRACT Relational inertia arising from formal roles and status hierarchies is endemic and problematic in many organizations. This study examines how role-power expansion for those in the middle of hierarchical groups, a central but understudied population, affects network structure and the nature of interactions within these groups. To do so, we conducted a field experiment assessing the effect of a formal role expansion for nurses involved in primary care delivery on interactions within hierarchical care groups. We utilized wearable social sensors to collect second-by-second data on face-to-face interactions, conversational characteristics, and body movements which allowed us to study who interacted with who in workgroups, as well as how interactions occurred. We find that role-power expansion in hierarchical contexts can produce structurally desired effects and is one means of overcoming relational inertia. However, it ignites more contentious interactions, a response consistent with increased tension and status renegotiation in