This paper builds on two concepts, the first of which is the extended information processing model of expert design cognition. This proposes twelve internal psychological characteristics interacting with the external world of expert designers during the early phases of the design process. Here, I explore one of the characteristics, hierarchical abstraction, and adapt it into an alternative ontological model of decision making. The model serves as an in-depth descriptor of how designers from different domains transform their mental states using judgment and decision making through hierarchical abstraction. The second concept entails an expansion of the idea of synergistic vertical transformation as a framework for mapping expert designers’ design process. Here, I focus on hierarchical decision making as multi-directional, and inter-relating the internal and external world of designers. In doing so, I provide a coding tool for researchers interested in exploring designers’ complex decision making processes. Concurrently, the model serves as decision making tool in design and technology education classrooms. As such, the paper focuses on the ontology of conceptual structures that support the early phases of the design process. This was based on empirical research.