Talia Lavie

Benefits and costs of adaptive user interfaces

The paper examines the positive and the possible adverse effects of adaptive user interfaces (AUIs) in the context of an in-vehicle telematic system as a function of four factors: (1) four different levels of adaptivity (ranging from manual to fully adaptive with intermediate levels); (2) different tasks; (3) routine (familiar) and non-routine (unfamiliar) situations; and (4) different user age groups. Both experiments included three sessions during which participants drove a simple driving simulator and performed tasks with the telematic system at one of the adaptivity levels. We measured task performance times and lane position variance. Adaptivity was not always equally beneficial, and its benefits depended on a number of factors, including the frequency in which the tasks were performed, the users age, the difficulty of the task and the users involvement in the task. In familiar, routine situations, a fully adaptive system was beneficial for all participants, particularly older ones. In unfamiliar situations, to which the AUI was not adjusted, cognitive workload increased substantially, adversely affecting performance. Intermediate levels of adaptivity keep users involved in the task and help them become more proficient when performing both routine and non-routine tasks. However, intermediate levels of adaptivity should also be implemented with care, because they may also have adverse effects when users encounter non-routine situations.

Highlighting items as means of adaptive assistance

Providing adaptive help during interaction with the system can be used to assist users in accomplishing their tasks. We propose providing guidance by highlighting the steps required for performing a task that the user intends to complete according to the prediction of a system. We present a study aimed at examining whether highlighting intended user steps in menus and toolbars as a means of assisting users in performing tasks is useful in terms of user response and performance. We also examined the effects of different accuracy levels of help and the control format on user response and performance. An experiment was conducted in which 64 participants performed tasks using menus and toolbars of a simulated email application. Participants were offered a highlighted guidance of the required steps in varying levels of accuracy (100%, 80%, 60% and no guidance). Our results support the benefits of highlighted help both in user performance times and in user satisfaction from receiving such assistance. Users found the assistance necessary and helpful and by the same token not unduly intrusive. Additionally, users felt that such assistance generally helped in reducing performance time on tasks. We did not find a significant difference when users receiving help at 80% accuracy was compared to those receiving help at 100% accuracy; however, such a difference does appear for those receiving 60% accuracy. In such cases, we found that the users satisfaction level, perceived usefulness and trust in the system decreased while their notion of perceived intrusiveness increased. We conclude that assisting users by highlighting the required steps is useful so long as the minimal accuracy level of help is higher than 60%. Our study has implications on the implementation of highlighting next steps as a means of adaptive help and on integrating probability-based algorithms such as intention prediction to adaptive assistance systems.

Perceptions of electronic navigation displays

This study evaluated aesthetics and usability of in-vehicle electronic navigation maps. Experiment 1 examined map displays that varied in the amount of information presented, abstraction level, graphic/colour style and the existence of landmarks in both urban and rural environments using objective and subjective measures. Twenty participants performed navigation/localisation tasks using various map configurations while driving a driving simulator and completed usability and aesthetic questionnaires. The minimal detail map produced better performances and higher usability and aesthetic ratings when using maps with no landmarks. Adding information in the form of landmarks was found advantageous compared to additional textual information. Abstractions were most advantageous when combined with minimal amount of detail. Moderate abstractions were sufficient for obtaining the desired benefits when more details were present. The graphic/colour style affected subjective perceptions. Overall, high correlations were found for the perceived aesthetics and usability scales, however, low correlations were found between actual usability (i.e. performance) and perceived usability pointing to the importance of using both objective and subjective usability measures. Experiment 2 examined how maps varying in their aesthetic level (aesthetic versus non-aesthetic), different colour arrangements, and 2D versus 3D landmarks affect subjective and objective measures. Participants distinguished between usability and aesthetic perceptions and usability perceptions were less affected by aesthetics when the aesthetic level of the maps was low. Colour arrangement did not affect the measures examined. Both 2D and 3D landmarks were found to be aesthetic and usable. We conclude this article with guidelines for designing in-vehicle navigation map displays.

Adaptive user interfaces for in-vehicle devices

Adaptive user interfaces (AUIs) have become the focus of various scientific disciplines and are studied extensively over the last decade. The studies exploring the field investigate a broad range of adaptation methods in different types of applications. Although some progress was made in the study of AUIs, many issues need additional exploring. The objective of this research is to extend previous research on AUI and to examine different levels of adaptivity in AUIs, rather than viewing adaptivity as an all or none process. This research will attempt to identify the levels of adaptivity appropriate for different users, tasks and situations when using AUIs. In particular, the research will assess the effects of different levels of adaptivity on the performance of routine and infrequent tasks. A series of experiments will be conducted to develop and evaluate a model specifying the factors that influence the users interaction with the AUI. Four different levels of adaptivity will be used, ranging from totally manual to fully adaptive with two intermediate levels. The AUI will be examined in the context of in-vehicle systems. The results of the research are expected to facilitate a better understanding of AUIs, clarify uncertainties and specify the situations in which adaptivity should be beneficial. Finally, the results of this research will assist in-vehicle system designers, by providing guiding principles for designing more usable AUIs.