Gulfs of expectation: eliciting and verifying differences in trust expectations using personas

Personas are a common tool used in Human Computer Interaction to represent the needs and expectations of a system’s stakeholders, but they are also grounded in large amounts of qualitative data. Our aim is to make use of this data to anticipate the differences between a user persona’s expectations of a system, and the expectations held by its developers. This paper introduces the idea of gulfs of expectation – the gap between the expectations held by a user about a system and its developers, and the expectations held by a developer about the system and its users. By evaluating these differences in expectation against a formal representation of a system, we demonstrate how differences between the anticipated user and developer mental models of the system can be verified. We illustrate this using a case study where persona characteristics were analysed to identify divergent behaviour and potential security breaches as a result of differing trust expectations.