Abstract
Different kinds of controlled natural language (CNL) have been proposed as a front-end for Semantic Web systems, in order to make them more accessible to users with no background in formal notations and methods. This paper investigates whether OWL statements in CNL are indeed easier to understand than in other notations. To this aim, an experiment with 64 participants was conducted that compares a controlled natural language to a classical OWL notation. Concretely, Attempto Controlled English was compared to a simplified version of the Manchester OWL Syntax. For a reliable and tool-independent evaluation of understandability, the experiment is based on a novel evaluation framework making use of simple and intuitive diagrams. The results show that CNL is easier to understand, needs less learning time, and is more accepted by its users.