Steven M. Belz

A New Class of Auditory Warning Signals for Complex Systems: Auditory Icons

This simulator-based study examined conventional auditory warnings (tonal, nonverbal sounds) and auditory icons (representational, nonverbal sounds), alone and in combination with a dash-mounted visual display, to present information about impending collision situations to commercial motor vehicle operators. Brake response times were measured for impending front-to-rear collision scenarios under 6 display configurations, 2 vehicle speeds, and 2 levels of headway. Accident occurrence was measured for impending side collision scenarios under 2 vehicle speeds, 2 levels of visual workload, 2 auditory displays, absence/presence of mirrors, and absence/presence of a dash-mounted iconic visual display. For both front-to-rear and side collision scenarios, auditory icons elicited significantly improved driver performance over conventional auditory warnings. Driver performance improved when collision warning information was presented through multiple modalities. Brake response times were significantly faster for impending front-to-rear collision scenarios using the longer headway condition. The presence of mirrors significantly reduced the number of accidents for impending side collision scenarios. Subjective preference data indicated that participants preferred multimodal displays over single-modality displays. Actual or potential applications for this research include auditory displays and warnings, information presentation, and the development of alternative user interfaces.

The user action framework

Although various methods exist for performing usability evaluation, they lack a systematic framework for guiding and structuring the assessment and reporting activities. Consequently, analysis and reporting of usability data are ad hoc and do not live up to their potential in cost effectiveness, and usability engineering support tools are not well integrated. We developed the User Action Framework, a structured knowledge base of usability concepts and issues, as a framework on which to build a broad suite of usability engineering support tools. The User Action Framework helps to guide the development of each tool and to integrate the set of tools in the practitioners working environment. An important characteristic of the User Action Framework is its own reliability in term of consistent use by practitioners. Consistent understanding and reporting of the underlying causes of usability problems are requirements for cost-effective analysis and redesign. Thus, high reliability in terms of agreement by users on what the User Action Framework means and how it is used is essential for its role as a common foundation for the tools. Here we describe how we achieved high reliability in the User Action Framework, and we support the claim with strongly positive results of a summative reliability study conducted to measure agreement among 10 usability experts in classifying 15 different usability problems. Reliability data from the User Action Framework are also compared to data collected from nine of the same usability experts using a classic heuristic evaluation technique.

Testing a Framework for Reliable Classification of Usability Problems

The User Action Framework (UAF) is a knowledge base of usability issues and concepts structured to provide a framework and method for classifying usability problems identified during usability evaluation. The UAF is essentially a hierarchical structure of usability attributes that users traverse as a decision structure, selecting the most appropriate classification category and sub-category at each level of the hierarchy. The cumulative set of category choices along the classification path is taken as a sequence of usability attributes that determines a complete classification description of the usability problem in question. The UAF itself has been the subject of usability evaluation and is the product of an extensive, iterative design process. In this paper we report on the reliability of the UAF by measuring the agreement of 10 experienced usability practitioners as they classify 15 different usability problems.

Auditory Icons as Impending Collision System Warning Signals in Commercial Motor Vehicles

This simulator-based study examined the use of conventional auditory warnings (tonal, non-verbal sounds) and auditory icons (representational, non-verbal sounds), alone and in combination with a dash-mounted visual display to warn commercial motor vehicle operators of impending front-to-rear and side collision situations. Driver performance was measured in the simulated driving task via brake response time in the front-to-rear collision scenarios and via a count of accident occurrence in the side collision scenarios. For both front-to-rear and side collision scenarios, auditory icons elicited significantly improved driver performance over conventional auditory warnings. Driver performance improved when collision warning information was presented through multiple modalities.

A Methodology for Selecting Auditory Icons for Use in Commercial Motor Vehicles

This paper describes work carried out to investigate the selection of auditory icons within the domain of commercial motor vehicles. Auditory icons are representational sounds in that they have specific, stereotypical meanings. While typical non-verbal sounds are defined by their particular acoustic parameters, auditory icons are defined by the objects or actions that created the sounds. Previously, researchers have relied on expert opinion to assign meaning to auditory icons; however, problems have arisen when the experimenter-selected meanings did not agree with users opinions. Attention was focused on the auditory icons perceived meaning and perceived urgency in an attempt to reduce the influence of experimenter bias in the auditory icon selection process.

An On-Road Investigation of Commercial Motor Vehicle Operator Self Assessment of Fatigue as an Indicator of Driver Fatigue

This on-road field investigation employed, for the first time, a completely automated, trigger-based data collection system capable of evaluating driver performance in an extended duration real-world motor vehicle environment. The portion of the study reported herein examined the use of self-assessment of fatigue (Karolinska Sleep Scale) as an indicator of driver fatigue. Without exception, the regression analyses for the self-assessment of fatigue yielded models low in predictive ability and were not found to be a suitable indicator of driver fatigue in a real-world commercial driving environment. Various reasons for the failure of self-rating of fatigue as a valid measure are discussed.

Age-Related Differences in Navigational Performance within an Immersive Virtual Environment

This paper presents an empirical investigation of the effects of aging on spatial performance in an immersive virtual environment. Adults (20 to 75 years of age) were taught a route through a six-room virtual house, while wearing a helmet mounted display (HMD) and using a joystick to navigate the virtual environment. Participants viewed the environment under monoscopic conditions with a display resolution of 640 pixels by 480 pixels, a field-of-view (FOV) of 30° H × 22° V, and a scene update rate of 15 Hz. Participants performed tasks designed to assess their spatial knowledge in terms of landmark knowledge, route knowledge, and configuration knowledge metrics. Locomotion efficiency and landmark knowledge did not significantly change with age. As age increased, route and configuration knowledge significantly decreased while the time needed to complete virtual environment spatial tasks increased (p < 0.05). The occurrence of side effects was also recorded; however, no significant differences with respect to age were found. The results are discussed in terms of designing virtual environments for adults.