Folder navigation is the main way that computer users retrieve their personal files. However we know surprisingly little about navigation, particularly about how it is affected by the operating system used, the interface presentation and the folder structure. To investigate this, we asked 289 participants to retrieve 1,109 of their own active files. We analyzed the 4,948 resulting retrieval steps, i.e. moves through the hierarchical folder tree. Results show: (a) significant differences in overall retrieval time between PC and Mac that arise from different organizational strategies rather than interface design; (b) the default Windows presentation is suboptimal - if changed, retrieval time could be reduced substantially and (c) contrary to our expectations, folder depth did not affect step duration. We discuss possible reasons for these results and suggest directions for future research.

People are often required to catch up on information they have missed in meetings, because of lateness or scheduling conflicts. Catching up is a complex cognitive process where people try to understand the current conversation without access to prior discussion. We develop and evaluate a novel Catchup audio player that allows time-travel. It automatically identifies the gist of what was missed, allowing people to join the meeting late and still participate effectively. In a lab study, we evaluated people's understanding of meetings they had partly missed, by asking questions about meeting content. We tested whether providing Catchup gist overcomes the potential disadvantage that people must join even later - because catching up takes time. Catchup users understood meetings 70% better than controls who simply joined late. They were more confident of their understanding and indicated a positive attitude towards the tool. We are currently exploring more general applications of the time-travel approach.

Abstract Folder navigation is the main way that personal computer users retrieve their own files. People dedicate considerable time to creating systematic structures to facilitate such retrieval. Despite the prevalence of both manual organization and navigation, there is very little systematic data about how people actually carry out navigation, or about the relation between organization structure and retrieval parameters. The aims of our research were therefore to study users' folder structure, personal file navigation, and the relations between them. We asked 296 participants to retrieve 1,131 of their active files and analyzed each of the 5,035 navigation steps in these retrievals. Folder structures were found to be shallow (files were retrieved from mean depth of 2.86 folders), with small folders (a mean of 11.82 files per folder) containing many subfolders (M=10.64). Navigation was largely successful and efficient with participants successfully accessing 94% of their files and taking 14.76 seconds to do this on average. Retrieval time and success depended on folder size and depth. We therefore found the users' decision to avoid both deep structure and large folders to be adaptive. Finally, we used a predictive model to formulate the effect of folder depth and folder size on retrieval time, and suggested an optimization point in this trade‐off.