The study of affective aspects is being encouraging on Information Science in recent years. The objective of this research is to analyze the emotive expresssions performed on information seeking process during information system interaction proccess. From the theoric models developed by Kuhlthau (1991, 2004) and Nahl (2005) a cualitative case study is developed to research about the emotivity as complementary strategy to evaluate information systems. Preliminary results show that experimented emotions during interaction can modify the cognitive patterns and seeking strategies adopted by users. Variations over the patterns can be explained by emotions, which converts them into indicators about system interaction efficiency.