Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Information systems require input from their users in order to perform information retrieval. In many systems, that input is provided by interaction between users and intermediaries. The way users understand and express their information needs may be affected by the cognitive structures (schemata) by which they have organized their knowledge of the search topic, or by the schemata introduced in the questions which intermediaries ask.;The bibliographic and text-linguistic schemata studied in this research are related to two ways of thinking about textual materials. The bibliographic schema leads to an emphasis on elements of bibliographic description: authors, titles, and subject keywords. The text-linguistic schema leads to an emphasis on the structural components of texts: in this case the Purpose, Methodology, Findings and Discussion found in scientific report articles.;The first experiment introduced these two schemata at the point of knowledge acquisition, and in the user-intermediary interaction. When presented through intermediary questions, the bibliographic schema led to short responses with small numbers of subject keywords, while the text-linguistic schema led to long responses with large numbers of subject keywords. Open questions, which presented no specific schema, produced responses which were longer than responses to bibliographic questions but shorter than responses to text-linguistic questions. There was no evidence that the schema introduced at the time of knowledge acquisition had an effect on statements of information need.;The second experiment introduced the text-linguistic schema through questions posed on supplementary online search forms in a working information retrieval environment. Responses replicated the findings from the first experiment in terms of overall length of responses. In the case of one searcher, searches based on the information supplied in response to text-linguistic questions used significantly more words in the search expression, and achieved lower precision.;Questions posed by intermediaries introduce cognitive stuctures which affect the details contained in statements of information need presented by users of information systems. A schema based on text-linguistic categories can be useful in eliciting more details from users, but these additional details do not necessarily result in better information retrieval.



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.