Information Filtering systems learn user preferences either through explicit or implicit feedback. However, requiring users to explicitly rate items as part of the interface interaction can place a large burden on the user. Implicit feedback removes the burden of explicit user ratings by transparently monitoring user behavior such as time spent reading, mouse movement and scrolling behavior. Previous research has shown that task may affect the effectiveness of some implicit measures. In this work we report both qualitative and quantitative results of an initial study examining the correlation relationship between user time spent reading and relevance for three web search tasks: relevance judgment, simple question answering and complex question answering. This study indicates that the usefulness of time spent as a measure of user interest is related to task and becomes more useful as the task becomes more complex. Future directions for this research are presented.