Apple’s iOS Human Interface Guidelines, Google’s Android Design Guidlines, and others such as Luke Wroblewski’s Mobile First book provide valuable guidance for designing general mobile applications. Yet there are a number of design principles unique to crafting mobile search experiences in particular. Namely: prioritizing content over controls, providing answers over results, being sensitive to context, and ensuring cross-channel continuity.
Content Trumps Controls
Search is often accompanied by a number of knobs and dials: filters, breadcrumbs, sort controls, pagination; the list goes on. When moving from the design of desktop to mobile search interfaces, the temptation is to replicate all of these controls on the main search results screen. Yielding to this temptation, however, leads to cluttered, frustrating interfaces that add stumbling blocks to the user’s path.
The primary search screen of a mobile application should be focused on the clarity of search results; bells and whistles must take a back seat. Mobile users, after all, often use their devices for short bursts of time, enter fewer queries per search session than do desktop users, and may seek answers to simple, lookup-based information needs. These realities suggest that navigation bars should be kept to a minimum, filtering and sorting displaced off-screen, and pagination controls omitted so that the search results receive as much screen space as possible.
Left: 50% of AOL’s mobile search interface is consumed by chrome.
Answers over Results
In addition to minimizing search controls and emphasizing content, focusing on precision over recall is usually in the best interest of mobile users, particularly time-sensitive smartphone users. Precision, as you know, describes the accuracy of the top results. Because mobile users reformulate their queries less often than desktop users, prioritizing the relevance of the top few results is generally more useful than providing high recall.
Providing direct answers to users’ lookup queries can make the mobile search experience more efficient still. Rather than force users to click on a search result to discover straightforward facts, such as “director of third man movie”, for instance, a more desirable approach is to provide a computed answer directly on the search page, eliminating the need for further action.
But tablets are a different story. While phones are often used for short periods of time to accomplish tangible goals, tablets are more likely to be used for longer durations and with more casual information needs. Optimizing for precision over recall and answers over results is a good rule of thumb, but should be balanced with the user’s context.
Google provides a direct answer to the query.
Contextual Sensitivity
Few argue about the importance of context on mobile devices. But effectively designing for context is another matter. The trick is to carefully interpret the user’s current context so that the interface can be optimized accordingly, while being accurate and forgiving enough that users don’t get frustrated when the system identifies the context incorrectly. Interpreting the user’s context could include determining their task—driving, cooking, or doing bicycle repairs, for example—whether or not their physical location is important, or whether they’re alone or with others.
Each of these aspects of context, if correctly identified, provides opportunities for optimization. A query for “basel”, for example, could be interpreted as a city if the user is driving in Switzerland, or as an ingredient if the user’s task is cooking. A trivia-lookup query originating during a conversation with friends could prompt a direct answer, while a casual ‘window shopping’ query originating on a tablet via the sofa could be better addressed with an image grid that encourages undirected browsing.
Amazon’s Windowshop iPad app invites casual browsing.
Cross-Channel Continuity
Every business recognizes the value of consistency across channels: customers benefit from a coherent, holistic experience where the learning from one channel can be applied to all the rest. A user familiar with Amazon on the desktop will instantly recognize the similarity of Amazon’s mobile application, for instance. But while consistency ensures the learnability of each channel, continuity makes it personal. Continuity is adding an item to the shopping cart via a desktop computer, and having it appear in the shopping cart on your phone; it’s saving a search on your phone and returning to it later on your tablet. In other words, continuity ensures that your actions aren’t performed in isolation, but propagate from the source channel to each of the others.
Continuity between channels can facilitate the figure-it-out-later approach often taken by users, as well as reduce the number of information needs that fall through the cracks. For starters, search history should be synchronized across devices so that inconclusive information seeking can be easily followed up later. What’s more, allowing saved searches that are accessible from every channel enables users to organize and return to important, ongoing information needs.
Zillow allows users to save searches, but fails to synchronize them across devices.