204 Personal Content Experience: Managing Digital Life in the Mobile Age 6.1.1 Searching Searching is an important and complex cognitive process that is often related to personal content experiencing. It is often required to locate a piece of content, and several technical aspects are required to achieve effi cient searching. Searching as a human activity has been widely investigated. There are basically two criteria: the fi rst is the search criteria, that is, the query that the user inputs; and the other is the selection criteria, which is the means of choosing the relevant results (Bental et al. 2000). Dealing with both of them requires cognitive processing. Regarding search criteria, studies have shown that people do not use many keywords in searching, and Boolean operators, such as AND and OR, are not generally used. Furthermore, many users do not understand the logic behind these operators (Spink et al. 1999). There are numerous challenges for search user interface developers, espe- cially when searching personal content (instead of more or less imper- sonal web resources) is increasing among the general public. Regarding the selection criteria, the users need to explore the result space, to choose the most promising results, and to evaluate the relevance of the result. Aula (2005) has studied the search strategies of highly experienced, elderly, and less experienced web users. Not surprisingly, the results showed that highly experienced users are more successful in not only fi nding required information, but also in evaluating the search results. Aula suggests improvements to selection criteria, such as presenting textual result summaries. An important aspect of human behaviour is successive searching. As time progresses, many users search the same (or possibly other) resources for answers to the same or evolving problem at hand (Bateman 1998). Spink et al. (1999; 2001) found that this is also true for web searches. They also noticed that users tend to employ simple search strategies, and that they often conduct more than one search on any one topic, that is, they employ successive searching. Based on their analysis, they suggest that web search engines should provide a way of saving users searches for future use, in order to better support suc- cessive searching. Since then, search history has been implemented in, for instance, Google’s search toolbar. The discussion above concerns searching in general, yet in many cases it is targeted at web searches that concern mostly non-personal content. However, searching for personal content is different com- pared to web searches, especially as the user is familiar with many characteristics of their content, including the context related to it (Cutrell et al. 2006).