The dichotomy of radical and incremental innovation has been discussed in numerous literature sources and a great amount of advices on how to handle them in design processes has been provided. Nevertheless, only a minority of literature sources addresses the perception of radicalism from a user's perspective, meaning that there is less research on how users or, in other words, consumers perceive a radical degree of novelty of products. Furthermore, there is little research on how this perception can be measured.

This paper discusses the aforementioned user's perception and proposes a way to derive criteria which users take into account when they decide whether an idea or an innovation is radical or incremental. A concept for an investigative model was developed and applied by using it in the field with 49 test subjects. Consequently, a set of criteria was derived which concretises the decision whether a product was radical or not. The criteria were analyzed statistically and can be used by designers planning to develop a radical innovation in order to check whether the criteria people use to differentiate between radical and incremental products are fulfilled.