When is system support effective?
It is widely acknowledged that exploratory search tasks require more search support than currently provided on most commercial Information Retrieval (IR) systems. As a result, richer modes of interaction, and more functional IR systems are being developed. But these next generation IR systems come at a cost: they can place a large cognitive load on the user during interaction, and hamper progress. In this paper, we investigate the relationship between search tasks and search interfaces, and try to understand when system support is most effective for search tasks. We present a user study comprising known-item and exploratory search tasks and different interfaces that provide varying levels of system support. A quantitative and qualitative data analysis was conducted on the users' performances, preferences, and search behaviours. Our findings suggest that a relationship exists between the level of system support and search tasks, and that system support is most effective when it is enabling search activities appropriate to the task