In-vehicle information systems are becoming increasingly prevalent in cars. In addition to the usual issues associated with designing a user interface, these devices must be designed in such a way that they do not compromise driving safety. Most such devices are based on a hierarchical menu-based system. This paper explores two search-based interaction techniques as alternatives to the menu-based approach. The first alternative is quick search (similar to the Google search engine) across all items in the database. The second alternative is categorical search that constrains searches to predefined categories and subcategories.

Graf et al. perform a variety of experiments to test the alternative approaches. First, they measure computer response time across databases of various sizes. Then, they build prototype devices and use them to measure how much visual distraction they impose on users, as high visual distraction is a safety hazard. Finally, a driving simulator is used to quantitatively address subjects’ driving performance while operating an in-vehicle information system.

The overall conclusion of the paper is that both quick search and categorical search provide satisfactory performance, with a slight preference for the quick search alternative.

The paper is generally well written, providing a straightforward description of how the studies are performed. The one exception is the description of occlusion tests to measure visual distraction. This section of the paper is opaque, even to an experienced human-factors expert. However, it does not detract from the overall conclusions or from the solid technical approach that employs a variety of experiments to test the alternatives. The findings about the advisability of moving away from hierarchical menu-based systems is consistent with research elsewhere, such as the approaches used in some of the in-flight entertainment systems available to airline passengers.