Goal-oriented modelling is one of the most
important research developments in the requirements
engineering (RE) field. This paper conducts a systematic
analysis of the visual syntax of i*, one of the leading goaloriented
languages. Like most RE notations, i* is highly
visual. Yet surprisingly, there has been little debate about
or modification to its graphical conventions since it was
proposed more than a decade ago. We evaluate the i*
visual notation using a set of principles for designing
cognitively effective visual notations (the Physics of
Notations). The analysis reveals some serious flaws in the
notation together with some practical recommendations for
improvement. The results can be used to improve its
effectiveness in practice, particularly for communicating
with end users. A broader goal of the paper is to raise awareness about the importance of visual representation in
RE research, which has historically received little attention.