cognitive approach for building user model in an information retrieval context (poster session)  the recent development of communication networks and multimedia system provides users with the availability of a huge amount of information making worse the problem of information overload [9]. the evolution of system design is necessary becoming more user centred, and more personally involving. a review of survey studies on internet users since 1993 confirms that a greater percentage of people are becoming online citizens, and professionals are integrating more online components into their work process. a review of the experimental literature on internet user's reveals that there is intense interest in humanising the online environment by integrating affective and cognitive components [8].  we are specially in concern with the effects on the evolution on information retrieval. we can notice significant changes in the information retrieval world over the past five or so years due to the emergence of internet and one of its most important and widely used services, the world wide web (www) or simply the web.  while reviewing the progress of research in information retrieval and user modelling, we can observe that many systems and prtotypes are created [5], [10], [11], but all of them, share some basic limitations: the techniques used to represent knowledge in the user model is based on simple list of keyword, the type of the considered knowledge is very limited, usually restricted to single word, or to (some) structural characteristic: the learning capability are very poor.  we aim to propose a cognitive approach for building user model in an information retrieval context. in fact cognitive approach is based on identifying how users process information and what constitutes an appropriate model to represent this process, and because ir, under the cognitive paradigm takes the user into account in a high-priority way [1]. however, within the cognitive paradigm, there is no general model valid for our documentary approach that satisfactorily how user knowledge is represented for the purpose of processing information. the lack of such a model does not allow one to identify a user's cognitive state with regard to his or her information needs and requirements.  methodology adopting the cognitive viewpoint in ir are synthesised by daniel [4] in three groups, which comprise the representation of:    * users and their problem, which stems from the hypothesis proposed by belkin on the `anomalous states of knowledge' (ask), according to which the user searches for information    * search strategy, which compile the different ways search strategies and processes are carried out, depending on the variable involved - user, intermediary, ir systems [6],[7]    * document and information, which is considered a major goal of current ir research, since it embraces the whole corpus of studies about user models intended to eliminate the intermediary's role in retrieval system. the aim of this approach is to allow users direct access to the system by means of the representation of documents and intelligent interfaces.  user-centered paradigm now dominates in studies of information needs and information retrieval. we have the goal of developing new approaches to information retrieval which are based on user modelling techniques for building and managing the representation of the user preferances. in this paper, we describe two complementary approaches which are necessary for building user model and its integration in an information retrieval system:    * a conceptual one based on the description of knowledge needed by the user in an information retrieval context,    * a functional approach which deals with dynamic aspects of the model. within this approach we aim to determine the role played by the model in an information retrieval context.  in many studies of ir interesting in user modelling we find different kind of knowledge trying to describe user's need. so our conceptual approach has consisted in enumerating these knowledge and integrating them in their adequate components in information retrieval architecture. almost of these studies that identified cognitive characteristics have used quantitative methods to measure them. what is needed is a qualitative study and appropriate method to ascertain these cognitive characteristic [12].  our main objective is the development of techniques for modelling the user as an interactive part of ir, so we propose our functional approach which deals with identifying cognitive characteristic within the role played by the user model in an information retrieval architecture. so we began by presenting the conceptual approach and so the functional one.  amina sayeb belhassen nabil ben abdallah henda hadjami ben ghezala