Background and Objectives: In recent years, the number of information science researches on the value of emotions in the information behavior of individuals has dramatically increased (Nahl and Bilal, 2007). This approach suggests that, from a logical point of view, addressing emotions in the design of information systems is a need. Online information retrieval is a process in which the result of a user's search is affected by changes and emotional states; hence, logical procedures in the development of information retrieval systems are the inclusion of emotional aspects with the goal of optimizing user experience. For this reason, systems must be developed that are capable of intelligently identifying and responding to human emotions. In this vein, it is necessary to develop a framework for measuring and analyzing the emotional experiences of the user (Lopatovska, 2011). In the literature of information science on Human-Computer interaction (HCI), valuable studies have been done in the field of information-seeking behavior (Kim, 2008; Lopatovska, 2009; Arapakis, 2010; Behzadi sanatjoo, Fattahi, Salehi Fadardi, 1394). However, it seems that the relationship between emotions, the search experience of specific search functions, such as visited pages, the selection of URLs and specific queries, is less widely considered in research, Thus, the present research, focusing on the impact of the positive and negative emotional aspects of searchers in online information retrieval, aims to investigate the performance and search experience in the results of the search. In general, the main purpose of this research is to investigate the role of positive and negative emotional aspects on the performance and experience of the Web users among different PhD students of humanities, basic sciences and technical engineering.
Methodology: This research is of a practical type and its implementation is based on the nature of the research using semi-experimental research method.
In the present study, an experiment with a pre-test and post-test group was employed. Before the beginning of the experiment, subjects were surveyed on negative and positive emotional aspects of the past week, using the PANAS Test Questionnaire. The research population of this research consisted of PhD students who were studying in Fars province (Shiraz University and Islamic Azad University, Shiraz Branch) in three fields of science (humanities, basic sciences, and technical engineering). With regard to the multitude and dispersion of the research population (106 people at the time of the research), a sample of 50 participants was selected based on purposeful sampling. Given the time-consuming process of data gathering and the limited time of the subjects, the participant's willingness to collaborate and experience the research phenomenon, namely, Web search experience, was very important. It should be noted that in the selection of sample participants among PhD students, criteria were set for them such as PhD students in the second year onward, and PhD students who were writing their proposal or dissertation. To collect the required data, the following instruments were used:
Questionnaire 1: The first questionnaire for Positive Affect Negative Affect Scale (PANAS) consisted of 20 questions in the Likert scale consisting of a number of words presented by Watson, Clarke and Tellegen (1998). This scale aimed to describe different emotions of the subject during the past week, before and after the search for scenarios.
Questionnaire 2: The second questionnaire to measure the search experience included 6 questions in the Likert scale that was completed by each participant following each search. This questionnaire was also used previously in some related researches (Lopatovska, 2009). To increase the validity of the questionnaires items, with professors’ recommendations, some changes were made in the context of the questions asked. Also, in order to assess the internal consistency of items, Cronbach's alpha formula was used and the amount of reliability estimated was 0.731, which seems acceptable. Log File Analytic: In this study, variables that indicated the search function were considered as a set of specific search behaviors. All performance variables were extracted from the operation of log files using the software Morae (a software to record and analyze the users’ amount of applicability and type of experience in computer programs use) during the searches, including: Task Time, All URL, Reviewed Hits, Google Pages, Unique Queries, T view Results, and Bounce Rate per visit to each site.
 Findings: The average positive and negative emotions reported by users before and after simple and difficult tasks of searching on the Web in different fields of science showed that the average positive emotions in different fields of science after the search were increased compared to the previous search. Negative emotions in difficult tasks to search in two groups of humanities and basic sciences were the same before searching and after difficult search, but after a simple search, negative emotions in basic sciences decreased. Also, the findings of the research showed that the level of emotions reported has a significant relationship with the search type.
The results of the canonical analysis in examining the relationship between the positive and negative emotional aspects before the search with the users’ search function showed that as the amount of positive emotional aspect before the search increases, the value of the variables, results pages, average rates Bounce Rate, Time view Results the search of Google pages and unique queries decreases, and mean time to visit each site and URLs variables increased. Also, as the amount of negative emotional aspect before the search increases, the value of the variables, Search Pages Results, average Bounce rate, and T View Results of URL decreases, and Talking Time, Google Pages, Unique queries, The average Review Hits of URLs increases; in other words, among those who have a negative emotional aspect, fewer URLs visited. According to the findings, in short, in the first and second functions, the positive emotional aspect in the simple search function and the negative emotional aspect in the difficult search, as an explanatory variable of the combined search function, have been entered.
Discussion:    The results of the study of the average positive and negative affections introduced by the users before and after simple and difficult tasks of searching on the Web in terms of various fields of science showed that the information search process on the Web is influenced by various factors, and different users with subject specialization, various education and varied training earn a different return on their Web search process.
Investigating emotional characteristics and the search experience as one of the most effective factors on the information-seeking behavior of the searchers showed that there is a relationship between the positive and negative emotional aspects of users and their information-seeking experience of Web (e.g., the pleasure of the search experience, the interest in the search job, familiarity with similar searches, the explicit purpose of the search and satisfaction with search results).
The results of the research on the simple and difficult search functions indicated that the user's emotional characteristics played a prominent role in the efficient use of information retrieval systems, and that the experiences and performance of the search during a search were influenced by the positive and negative emotional states of the user prior to his/her participation in the search.
The results of this study, which are based on the patterns and emotional aspects of the positive and negative aspects of the information-seeking process, can be used to create emotional expert systems. Systems that identify, store, and present at the right time, users’ models to the people fitting their emotional features. Obviously, without a complete understanding of how users with the various emotions are looking for the Web, improving information retrieval systems, including the web, will not be possible.
Given the effects of emotions before retrieving on the emotions after information retrieval among users, designers of information retrieval systems must provide the ground that the negative emotions of users before the search change to positive emotions with clear, suitable and attractive user-environment settings, and then the user with a positive emotional state start to search and retrieve information. On the other hand, the findings and methodology of this research can be used in the design of user interfaces for various types of websites and library software. New-generation designers of libraries and retrieval systems need to design new environments in a more user-friendly way so that they can act more flexibly and adapt to the needs of their users. Paying attention to the emotions of users can be a good solution in this regard.