Sorting out Searching on Small Screen Devices

Small handheld devices – mobile phones, PDAs etc – are increasingly being used to access the Web. Search engines are the most used Web services and are an important user support. Recently, Google™ (and other search engine providers) have started to offer their services on the small screen. This paper presents a detailed evaluation of the how easy to use such services are in these new contexts. An experiment was carried out to compare users’ abilities to complete realistic tourist orientated search tasks using a WAP, PDA-sized and conventional, desktop interface to the full Google™ index. With all three interfaces, when users succeed in completing a task, they do so quickly (within 2 to 3 minutes) and using few interactions with the search engine. When they fail, though, they fail badly. The paper examines the causes of failures in small screen searching and proposes guidelines for improving these interfaces.

Read the full paper, or for those in a hurry, here are some design suggestions to improve search engine interaction on small screens:

Clearly screen size has a major impact on user performance. Success rates drop and even the time to complete successful searches increases. From our evaluations and observations, we propose several ways that the Google WAP and PDA interfaces might be improved. These guidelines will also be of interest to others developing search interfaces for small screen contexts.

• Reduce the amount of page-to-page navigation needed to view search results. Users do not look at many search result pages and also prefer not to shuffle with groups of pages to view information. As we observed in [11], page-to-page navigation is very costly when browsing in general, and in our current observations we have seen similar behaviour when users are browsing search results. Although increasing the number of results on a WAP card or PDA screen will lead to increased vertical scrolling, this additional user effort affects performance to a lesser extent than the page-to-page navigation.
• Provide more rather than less information for each search result. Users value good quality information about search results. As we have seen, selecting a search result, particularly for WAP, is a very “risky” action. Users were clearly observed seeking information to guide their next step as they browsed the search result list, and expressed uncertainty when given what they felt was inadequate information. Better quality information should support user confidence, and if appropriate should also enhance performance. For the WAP interface especially, more information should be provided and should be presented using the wrapped round textrather than the automatic horizontal scroll method [1]. Clearly, for WAP given the limited deck size, there needs to be a technical trade-off between this guideline and the first.
• Provide a quick way for users to know whether a search result points to a conventional HTML page or a small screen optimised page. If search results are not optimised for WAP pages, there is very little point in WAP users selecting them: users will simply become lost as they struggle through the many WAP cards needed to represent the HTML page. We observed that frames-based sites can be particularly damaging, even with sophisticated conversion. Although the larger display area on PDA type computers reduces the problem, pages adapted for these devices will be easier to use. The search result list could use a small icon or text device to let users scan and find small screen suitable information. It may not be possible, for any one of a host of reasons, to provide a small-screen optimised version of a site. Where an optimised form is available, users will generally perform better, through reduced scrolling, so assis t them in making an informed choice before committing (and then often failing on poorly converted pages).
• Pre-process conventional pages for better usability in small screen contexts. Google already pre-processes non-WAP pages so they can be displayed on WAP devices. More sophisticated adaptations for both WAP and PDA sized screens are possible (see Section 3.1). This could lead to much increased user effectiveness.
• Adapt for vertical scrolling – in our first evaluation [11] and our observations in this evaluation, users tend to scroll vertically rather than horizontally – design with this bias in mind; information which requires significant sideways scrolling will often never be seen.