Prototypes are complex artifacts in the design process. They are an essential part of the product development process, and yet one of the least formally explored areas of design practice. This research is a qualitative, empirical, and industrial-based study using inductive ethnographic observations to further our understanding of the various roles prototypes play on design teams in organizations. This research observed the entire product development process within three companies in the fields of consumer electronics, footwear, and medical devices. The guiding research questions were: What is a prototype? What are the roles of prototypes on design teams? How do these roles change or manifest throughout the process?

Through analysis, I uncovered that prototypes are tools for enhanced communication, increased learning, and informed decision-making. I provide a newly modified definition of a prototype, which is used to expand designers' mental models. I proved that prototypes are dynamic artifacts that shape social situations during product development. Specifically, I uncovered that the primary purpose of prototypes changes based on the context of use. I explored five unique contexts, and I describe how the primary role of prototypes shifts between a tool for communication, learning, and decision-making based on the context of use within companies. These insights can help designers, project managers, and other stakeholders become aware of the many benefits and biases that prototypes create in common situations throughout the design process.

This research is significant because it provides empirical insights into the role of prototypes in professional environments. There is a need to better understand design practices in industry, such as prototyping, and translate these findings back into design education. I have already begun to translate this research to academia, by creating prototyping workshops, lessons, and tools to aid students in mechanical engineering. Ultimately, this research validates prior prototyping theories and claims, while adding new perspectives through further exploiting each role of a prototype and how it changes over time and with use. This research provides a new framework for viewing prototypes, specifically how prototypes have agency. Prototypes enable actions to occur, and they influence human behavior in social situations.