The article presents an assessment method for the designers' use of abstraction skills in the process of CT. Starting with questioning how abstraction partakes in design and computer sciences, the study focuses on the impacts of making conceptual and procedural abstractions in CT. For that, it offers an assessment method to explore whether a visual thinker's ability to make abstractions has any impact on their process of visual computing. As a concept, CT is considered as a mental activity for formulating a problem to admit a computational solution by combining the intelligence of humans and machines. It is addressed as a collection of mental tools and concepts that are borrowed from computer sciences. Within this regard, architecture is one of the fields that require careful consideration of these cognitive aspects towards CT. Although both computer and design sciences value abstraction in similar ways, its introduction to the design field slightly differs from its introduction to computer sciences. Considering the differences in their conceptual background and reflective practices, it can be said that the abstraction of a visual thinker may not always constitute the way that CT requires. Based on a two-stage experiment in a CAD modeling framework, the developed methodology revealed that the designers' abilities to make abstractions at a procedural level partake a significant role in their visual computing. While the first experiment is conducted with 3 sophomore architecture students, the second was conducted with the participation of 3 non-designers along with the same architecture students.