Purpose:  human-information interactions must be considered in order to be able to interactively design Information Retrieval Systems (IRS). In this regard, study of users’ interactions must be based on their socio-cultural context (specifically work tasks). Accordingly, this paper aims to explore the use of information-interaction criteria among students in the information searching process according to different kinds of their work tasks.  Methodology: This research is applied qualitative method using exploratory study. The research population consisted of MSc students of Ferdowsi university of Mashhad enrolled in 2012-13  academic year. In 3 stages of sampling (random stratified, quota, and voluntary sampling), 30 cases were selected. Each of these cases searched 6 different types of simulated work tasks. Interaction criteria were extracted ? Content analysis of aloud thinking reports. Validity of tools was verified through Faculties of KIS at Ferdowsi university of Mashhad. Also,0.78  Kripendorff’s alpha ratio based on an agreement between the inter – coder indicates the Dependability  of content analysis. Findings: The findings show that in addition to ‘topic’ criteria, other interaction criteria impact on information- interaction of users, such as: ‘search results ranking’, ‘domain knowledge of user’, ‘layout’, ‘type of information resource’ and etc. based on the level of objective complexity and product of  work tasks, information-interaction criteria change. Conclusion: the users pay attention to different information-interaction criteria in process of information searching, considering to variety of work tasks (level of objective complexity and product). So, it is necessary to pay attention to work task characteristics in order to design interactive and personalized IR systems.