When on the move, cognitive resources are reserved partly for passively monitoring and reacting to contexts and events, and partly for actively constructing them. The Resource Competition Framework (RCF), building on the Multiple Resources Theory, explains how psychosocial tasks typical of mobile situations compete for cognitive resources and then suggests that this leads to the depletion of resources for task interaction and eventually results in the breakdown of fluent interaction. RCF predictions were tested in a semi-naturalistic field study measuring attention during the performance of assigned Web search tasks on mobile phone while moving through nine varied but typical urban situations. Notably, we discovered up to eight-fold differentials between micro-level measurements of attentional resource fragmentation, for example from spans of over 16 seconds in a laboratory condition dropping to bursts of just a few seconds in difficult mobile situations. By calibrating perceptual sampling, reducing resource usage for tasks of secondary importance, and resisting the impulse to switch tasks before finalization, participants compensated for the resource depletion. The findings are compared to previous studies in office contexts. The work is valuable in many areas of HCI dealing with mobility. ACM Classification Keywords: H5.m. Information interfaces and presentation (e.g., HCI): Miscellaneous

Interruptions have gained in importance as a topic in current HCI research. Through a series of experiments, we take a step toward analyzing the active role of human memory in controlling interruptions. The results of these experiments lead us to propose a novel approach, the skilled memory approach, to how UIs can support memory in skilled management of and recovery from interruptions.

Strategies in searching a link from a web page can rely either on expectations of prototypical locations or on memories of earlier visits to the page. What is the nature of these expectations, how are locations of web objects remembered, and how do the expectations and memories control search? These questions were investigated in an experiment where, in the experimental group, nine experienced users searched links. To obtain information about expectations, users’ eye movements were recorded. Memory for locations of web objects was tested immediately afterwards. In the control group, nine matched users had to guess the locations of web objects without seeing the page. Eye-movement data and control group’s guesses both indicated a robust expectation of links residing on the left side of the page. Only the location of task-relevant web objects could be recollected, indicating that deep processing is required for memories to become consciously accessible. A comparison between the experimental group and the control group revealed that what was represented in memory was not an individual link’s location but the approximate locations of link panels. We argue that practice-related decreases in reaction time were caused by semantic priming. Roles for the different types of memory in link search are discussed.