Unmasking Mode Errors: A New Application of Task Knowledge Principles to the Knowledge Gaps in Cockpit Design

In the complexity of modern, computerised systems, the current system state can come as an unpleasant shock to even an experienced user. The dominant thinking in this field [Palmer, 1995, Palmer et al, 1993, Degani et al, 1996, Rushby 1999] suggests that much of this "automation surprise" [Palmer 1995] comes as a result of mode error. In this paper, we will show that this is a fundamental misclassification and show the existence of a deeper problem, which we identify as a task knowledge gap [Johnson 1992] between operator and system. We suggest a new design solution, based on this re-classification and evaluate this new approach through the redesign of interfaces in a simulation of a well-documented air-incident. The results of our evaluation show the redesign to be significantly less prone to the depicted error. We conclude by considering the implications of these results in terms of task knowledge principles.