Modelling and evaluating drivers’ interactions with in-vehicle information systems (IVIS)

Abstract

Evaluating the usability of In-Vehicle Information Systems (IVIS) guides engineers in understanding the interaction design limitations of current systems and assessing the potential of concept technologies. The complexity and diversity of the driving task presents a unique challenge in defining usability: user-IVIS interactions create a dual-task scenario, in which conflicts can arise between the primary driving tasks and secondary IVIS tasks. This, and the safety-critical nature of driving, must be specified in defining and evaluating IVIS usability.Work was carried out in the initial phases of this project to define usability for IVIS and to develop a framework for evaluation. One of the key findings of this work was the importance of context-of-use in defining usability, so that specific usability criteria and appropriate evaluation methods can be identified. The evaluation methods in the framework were categorised as either analytic, i.e. applicable at the earliest stages of product development to predict performance and usability; or empirical, i.e. to measure user performance under simulated or real-world conditions. Two case studies have shown that the evaluation framework is sensitive to differences between IVIS and can identify important usability issues, which can be used to inform design improvements.The later stages of the project have focussed on Multimodal Critical Path Analysis (CPA). Initially, CPA was used to predict IVIS task interaction times for a stationary vehicle. The CPA model was extended to produce fastperson and slowperson task time estimates, as well as average predictions. In order for the CPA to be of real use to designers of IVIS, it also needed to predict dual-task IVIS interaction times, i.e. time taken to perform IVIS tasks whilst driving. A hypothesis of shared glances was developed, proposing that drivers are able to monitor two visual information sources simultaneously. The CPA technique was extended for prediction of dual-task interaction times by modelling this shared glance pattern. The hypothesis has important implications for theories of visual behaviour and for the design of future IVIS