Abstract—Several Requirements Engineering (RE) methods have been proposed to analyze and model requirements specifications. However, these methods have often been only partially evaluated and few attempts exist in literature to study and evaluate RE methods through experiments. In this paper, we document an empirical study that has been performed to evaluate the comprehension of requirements which were expressed in Tropos4AS. Tropos4AS specializes the goal-oriented software engineering methodology Tropos for the case of self-adaptive systems. In the experiment, we asked subjects to perform comprehension tasks on requirements specifications expressed in Tropos4AS and in Tropos, respectively. Results show that Tropos4AS is more effective than Tropos in describing requirements of self-adaptive systems, especially when the models are used by novice requirements engineers.