In information systems, documents and other information resources are grouped into categories in order to facilitate efficient retrieval. Interaction with these categories has the potential to modify the users conception of his information needs. In many cases, the interaction will increase the salience of that category to the user. This study seeks to identify cases when the opposite effect occurs, so that interaction with a category decreases its salience to the user. This might happen when the user selects from a set of resources within a category, if that process causes the backgrounding of the common attribute of category membership. The backgrounding effect is expected to be strongest when the priming effects associated with the category are weakest, such as when the categorys label is not provided, or when the concepts related to the category are already highly salient to the user.