Apshvalka, D.; Donina, D.; Kirikova, M. (2009): Understanding the Problems of Requirements Elicitation Process: A Human Perspective, Information Systems Development, Springer, pp 211-223
Understanding the Problems of Requirements Elicitation Process: a Human Perspective
Dace Apshvalka1, Dace Donina 2, and Marite Kirikova 3 1
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Riga Technical University, Department of System Theory and Design,
[email protected] Riga Technical University, Department of System Theory and Design,
[email protected] Riga Technical University, Department of System Theory and Design,
[email protected]
Abstract. Issues about requirements elicitation have been an ongoing problem area since the very earliest days of computing. However, incorrect requirements, misunderstood requirements, and many other requirement problems are still present in systems development projects. The purpose of this paper is to look at the causes of problems in requirement elicitation process. We will look at these problems from the human perspective, trying to understand the role of human cognitive, emotional, motivational, and social processes. Our goal is to understand the aspects which should be taken into consideration when choosing requirement elicitation approaches and methods.
1 Introduction Rapid development of information and communication technologies and new information storage and exchange possibilities have made knowledge the most valuable asset and collaboration skills the best tool for the success of a modern business and daily life activities (Davenport & Prusak 1998; Nonaka & Takeuchi 1995). Knowledge and knowledge processes has always been an important subject of research among scientists belonging to different research branches. Processes where value can only be created through the fulfillment of particular knowledge requirements of the process participants are called knowledge-intensive processes (Richtervon Hagen et al. 2005). Based on this definition we can say that information systems development (ISD) process is also a knowledge-intensive process. In the ISD process many participants are involved and the success of the ISD process and the quality of the achieved result is very much dependent on the knowledge of many different participants and the productivity of their collaboration. ISD process consists of many sub-processes and each of them is more or less knowledge intensive process. However, one of the most knowledge intensive sub-processes in ISD is requirement elici-
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tation. It involves many different stakeholders, with different interests, expectations, and domain knowledge, which should be aligned, distilled, and incorporated into requirement specification. All their relevant knowledge, experience and expectations about the future information system are crucial for the success of the whole ISD process and the final system. Issues regarding requirement elicitation, analyzing, documenting and communicating have been an ongoing problem area since the very earliest days of computing. However, incorrect requirements, misunderstood requirements, and many other requirement problems are still present in systems development projects (Avison & Fitzgerald 2006). Avison and Fitzgerald (2006) suggest that maybe it is impossible to solve the requirement problems as they are still present after thousands of years (since the first project of the mankind) of attempts to solve these problems. Nevertheless, many approaches, techniques and methodologies have been and are being developed to minimize errors and misunderstandings in requirement process. The purpose of this paper is not to give a contribution to the requirement elicitation methods or techniques, but to look at the causes of problems in requirement elicitation process. We will look at these problems from the human perspective, trying to understand the role of human cognitive, emotional, motivational, and social processes which cause misunderstandings, incompletely expressed information, misinterpretation and other threats for the success of requirement elicitation process. Our goal is to understand what aspects influence the knowledge and behavior of different stakeholders involved in the requirement elicitation process, and how they influence each others’ conceptual systems. This understanding can help us to interpret the usability of different existing requirement elicitation methods and techniques. We start our discussion in the second section with a brief look at the requirement elicitation process and problems. In the third section we focus on the theory of human knowledge and aspects influencing human knowledge. In the fourth section we discuss the requirements which are important for the success of requirement elicitation process.
2 Requirement Elicitation Process Requirements are regarded as the most important and crucial part of the systems development process and they are often the most misunderstood development issues (Avison & Fitzgerald 2006). Requirements are everything that the set of relevant stakeholders want from a system. Requirements engineer needs to identify relevant sources of requirements, elicit requirements from identified sources, analyze and document elicited requirements, communicating requirements (Avison & Fitzgerald 2006). Requirement elicitation is a process of capturing all relevant requirements from identified sources – documents, systems, stakeholders, and others. In this paper we focus on the process of requirement elicitation from the identified stakeholders. By stakeholders we understand any person who will be affected by the developed sys-
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tem directly or indirectly. Such persons are, for example, customers, end-users, domain experts, senior or line management, and others. Capturing requirements from stakeholders is knowledge-intensive process because the value of the process can only be created from the knowledge of process participants. The success of requirement elicitation process depends on the success of communication, collaboration, and understanding among different stakeholders and between stakeholders and requirements engineer. Communication is about sending and receiving information. Collaboration is actively working together to deliver a work product or to make a decision (Cockburn & Highsmith 2001). Understanding is alignment of conceptual systems (Davidson et al. 2003). Requirements engineering literature identifies several problems in the requirement elicitation process (Avison & Fitzgerald 2006: p101-104; Sommerville 2004: p.146). In this paper we will focus our attention on the problems caused by insufficient communication between the process participants. Some of these problems are as follows: • Missing requirements – stakeholders don’t mention all requirements because they don’t know what they want and they don’t know the possible options what a new system could offer, or they forget to tell about some requirements, or requirements engineer forgets to ask some specific questions. • Reluctant participation – stakeholders are not interested to participate sufficiently in the requirement elicitation process. • Misperception – requirements engineer incorrectly captures requirements. One of the reasons for misperception is that stakeholders express requirements in their terms and with implicit knowledge of their own work. Requirements engineer, without experience in the stakeholders’ domain, may misunderstand these requirements. • Disagreement – stakeholders disagree about some requirements. Different approaches and methods are developed to support requirement elicitation and to deal with possible problems in the requirement elicitation process. Some of the approaches are as follows (Hoffer et al. 2004): • Traditional approaches such as interviews, Nominal Group Technique, observation, analyzing procedures and documents. • Contemporary approaches, such as Joint Application Design, group support systems, CASE tools, prototypes. • Agile approaches, such as, continual user involvement, Agile Usage-Centered Design, Planning Game. However, none of these approaches can fully avoid misunderstandings and other problems in a requirement elicitation process. Our assumption is that these problems are caused because of the human-centered nature of requirement elicitation process. Most of the processes in the ISD life cycle can be more or less automated and formalized. But effective requirement elicitation from stakeholders requires face-to-face communication with stakeholders to avoid misunderstandings (Li et al. 2005). However, face-to-face communication is not a panacea for avoidance of misunderstand-
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ings. In some situations it can lead to even more misunderstandings than written or more formal ways of communication. Sutcliffe (2002) writes that natural language is a prone to misinterpretation and therefore requirement analysis has been a frequent cause of system failure. Human communication and the alignment of different conceptual systems involve cognitive and social processes which are still not fully understood even by cognitive and social scientists (Sun 2006) and little studied in the Requirements engineering field.
3 Inside the Human Mind Requirement analysis can be seen as discovery-based learning where we start with an obscure understanding of the problem domain and what is required for the new system. It is a cognitive process of understanding problems and communicating with people (Sutcliffe 2002). Our assumption is similar to one of Sutcliffe’s (2002) that given the fact that requirement elicitation is much about interpersonal communication, collaboration and personal cognition, understanding how these processes work and affect each other can help us to understand the causes of the problems in requirement elicitation process. This understanding can help us to interpret the usability of different existing requirement elicitation methods and techniques. As we have described in the previous section, requirement elicitation is knowledge-intensive process. It means that the main resource of the requirement elicitation process is knowledge and the success of the process result is based on the fulfillment of the knowledge requirements of the process participants. To understand the knowledge-intensive requirement elicitation process, we need to understand the concept of knowledge. There are many definitions of knowledge. The variety of the definitions depend on the knowledge definer’s perspective on knowledge (e.g., philosophical, managerial, engineering) and the objective why it has been necessary to define the knowledge. One of the most popular knowledge definitions in the managerial and business domain is given by Davenport and Prusak, and it states that knowledge is “a fluid mix of framed experience, values, contextual information, and expert insight that provides a framework for evaluation and incorporating new experiences and information. It originates and is applied in the minds of knowers (..) Knowledge exists within people, part and parcel of human complexity and unpredictability” (Davenport & Prusak 1998: p.5). This definition states that knowledge is something personal and resides in human minds. Therefore the next concept we need to understand is the concept of human mind or the ‘room’ of human knowledge. The traditional model of human mind is expressed by three basic human mental processes: cognition, emotion, and motivation. The original source of this structure comes from Plato who was arguing for a tripartite structure of the human soul (Davidson et al. 2003). Plato created these three concepts and put them in partial opposition to each other. While this doctrine has had many critics, still it profoundly affect-
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ed modern psychology where cognition is often seen as an antagonist to emotion (Davidson et al. 2003). However, a recent tendency in psychology as well as in other disciplines (e.g., computer science) is to study the interaction between cognition, emotion and motivation (Meredith et al. 2000; Sloman 2001; Picard 1997). Meredith and his colleagues (2000), based on the traditional view of mind, mentioned above, represent human knowledge as residing in a three dimensional space, where cognition, emotion, and motivation are three dimensions of knowledge space. The three dimensions affect each other and are closely interwoven. Each process pervades the other to a great extent. The same external stimulus results in responses from all three processes. None of the three exists in a vacuum without the other two. Since knowledge is at least cognitively based, it is impossible to know something without having an affect and conative (motivational) reaction to it, these reactions adding to and becoming a part of knowledge (Meredith et al. 2000). Affective science research shows that human affective states have a powerful influence on the way people perceive, interpret, represent and categorize information and the way they formulate attitudes and judgments. Emotions bias cognitive processing during judgement and inference. For example, happiness allows unusual associations and improves creative problem solving (Isen et al. 1987). The last several years have witnessed a bust of interest in the role of emotions in cognitive processes such as decision-making. Researchers have shown that even the affect that is unrelated to the decision at hand can have a significant impact on judgement and choice, but emotional deficits can degrade the quality of decisionmaking. Traditional decision-making theory paid little attention to emotion. Decision-making was viewed as a cognitive process where decision makers dispassionately choose actions that maximized the “utility” of potential consequences of their decisions (Davidson et al. 2003). It is regarded that there are two basic kinds of affective influence on decisionmaking: expected emotions and immediate emotions. Expected emotions consist of predictions about the emotional consequences of decision outcomes. They influence a person to select actions that maximize positive emotions and minimize negative emotions. Immediate emotions are experienced at the time of decision-making. Theories of decision-making, if they incorporate emotions at all, typically assume that expected emotions are the only emotions that matter. People are assumed to choose options that they expect will maximize positive emotions. However, not only expected emotions influence decision-making process. Also immediate emotions influence decisions by altering the decision maker’s perceptions of probabilities or outcomes or by altering the quality and quantity of processing decision-relevant signs (Davidson et al. 2003). The interrelationship between decision-making, immediate, and expected emotions is illustrated in the Fig. 1.
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Fig. 1. The interrelationship between decision-making, immediate, and expected emotions (Adapted from Davidson et al. 2003: p. 621)
Figure 2 represents human mental processes described in this section. Picture shows that knowledge is embedded in the human cognition, emotion and motivation space and formulates person’s judgments and attitudes. Knowledge (previous knowledge or experiences together with judgments and attitudes) influence the way person process information. Although information processing is also a cognitive process, in the picture it is displayed as a separate process (outside the process of cognition which forms one of the dimensions in the knowledge space) to outline the information processing processes. Information processing influence decisionmaking, as information is an important resource for making decisions. Decisionmaking is influenced also by other knowledge dimensions – motivation and emotion. During the decision-making process person’s emotion and motivation is influenced, and knowledge structures are changed as well. (Note that Fig. 2 is just a representation of the concepts described above. It is not a detailed process or conceptual model.)
Fig.2. Representation of human mental processes
Cognitive scientists tend to focus on the behavior of single individuals thinking and perceiving on their own. Although a significant amount of work has been done
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in cognitive science in studying individual cognition, the sociocultural processes and their relation to cognition have never been a focus of cognitive science (Sun 2006). However, humans are social beings. It means that humans are influenced by other humans, as well as humans are influencing other humans. Dynamic relationships are formed among different individuals and these relationships initiate changes in individual’s inner states, personality facets and knowledge. Cockburn and Highsmith (2001) note that what can be seen from the brainstorming and joint problem-solving sessions is that people working together with good communication and interaction can operate at higher levels than when they use their individual talents only.
4 Requirements for Successful Requirements Elicitation Process What can we learn from the theory of human knowledge and mental processes in the context of requirement elicitation? As requirement elicitation is knowledge-intensive process which involves different ‘knowledge holders’, it is necessary to understand how knowledge processes in the human mind work. When we will understand these processes, we will be able to adjust them in the right way to make the best use of the knowledge-intensiveness in the requirement elicitation process. As we discussed in the previous section, human knowledge is embedded into cognitive, emotional and motivational processes and all these processes influence human information processing and decision making (see Fig. 2). Therefore requirements engineer should choose methods and approaches, which support positive environment for the three mental processes in the stakeholders’ minds, to help, support and initiate stakeholders’ knowledge sharing and creation. Appropriately supported cognitive processes, positive emotional environment and sufficient level of stakeholders’ motivation are crucial for the successful requirement elicitation process. In this section we will discuss how to avoid problems mentioned in Section 2: missing requirements, reluctant participation, misperception, and disagreement.
4.1 Supporting Cognitive Processes As we have stated previously, one of the requirement elicitation problems is that stakeholders do not know what they want and what they know. Therefore the right knowledge should be triggered from outside the stakeholders’ minds by introducing them with possible options the new system could offer and by asking them about their knowledge domain and expertise. Studies of mind and knowledge shows that complex structures of human mind and human knowledge makes it difficult and sometimes even impossible for the knowledge owner to express and explain (to make explicit) particular ‘piece’ of his/her knowledge (Polanyi 1964; Ortner 2002). Very often even the owner of the original knowledge doesn’t know its real and/or complete meaning. Polanyi (1964: p.252) writes: “I can say nothing precisely. (…) I do not focally know what I mean, and though I could explore my meaning up to a point, I believe that my words (descriptive words) must mean more than I shall ever know, if they are to mean anything at all (..) We can know more than we can tell.”
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Requirements engineer should take this aspect into account when planning, organizing and leading requirement elicitation process. Requirements engineer is responsible for initiating stakeholders (the knowers of requirements) to tell as much as possible/necessary. How to help stakeholders to realize what they know and how to help them to express what they know? Ortner (2002) writes that information acts like a command or trigger that prompts the selection of a specific pattern in the mind. These impulses from outside are essential for ‘actuating’ knowledge or for arranging specific combinations of knowledge material into a specific structure and starting specific knowledge processes. It means that knowledge is context and outside impulse dependent. To elicit the right requirements from stakeholders it is necessary to provide them with the right context and the right impulses. Interview is one of the most common methods which support the knowledge triggering from stakeholders. Interviews are good for getting an overall understanding of what stakeholders do, how they might interact with the system and the difficulties that they face with the current system (Sommerville 2004). And, on the other hand, interviews also help stakeholders to get at least a basic understanding about aspects of their knowledge and working processes, in which requirements engineer is interested in, and about what kind of subjects they need to think about to give their valuable contribution into the development of the new system. Other methods of knowledge triggering are, for example, scenarios and prototyping. People find it easer to relate to real-life examples than to abstract descriptions as often used in interviews. Imagination of the possible interaction of the new system, are powerful way of triggering expression of specific requirements from stakeholders.
4.2 Supporting Emotional and Motivational Processes As we discussed in the previous section and as it is represented in Fig. 1 and Fig. 2, affect or emotion (these terms are often used as synonyms) has a powerful influence on person’s cognitive processes. Requirement elicitation involves many cognitive processes such as information perception, interpretation, representation and decisionmaking. Since person’s emotional state has a powerful influence on these processes, requirements engineer must not ignore this important aspect. Besides that, emotion has an influence on person’s motivation as well (See Fig. 2). Reluctant participation is one of the frequent problems in the requirement elicitation process (see Section 2). Therefore every recommendation about the factors influencing person’s motivation should be considered by requirements engineer. However, requirement literature tells little about the role of stakeholders’ emotions during the requirement elicitation process. (Although emotional state of requirements engineer is also important, we do not discuss it, assuming that he as a professional manages his emotion in the best way.) Requirements engineer needs to be attentive to recognize stakeholders’ emotional states to avoid possible threats. Such threat may be, for example, undesirable expected emotions (see Fig. 1) for the new system. Such emotions may occur, for example, when stakeholders imagine or realize that the new system will burden their habitual work processes, or make the working conditions less enjoyable, or provoke
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the firing of some employees as some work processes will be automated. Such expected emotions during the requirement elicitation process affect stakeholders’ decision-making and knowledge sharing in a negative way. Therefore requirements engineer needs to work as a motivator and psychologist to predict, detect and avoid unwilling emotions and to arouse motivating emotions, such as happiness, hope, inspiration, openness and the like.
4.3 Supporting Knowledge Exchange Another challenging aspect that requirements engineer should consider is the social nature of humans. Much deeper and detailed research should be done to understand how individuals influence each other’s cognitive processes, as well as each other’s emotion and motivation. In this paper we will mention rather general assumption based on Knowledge Management literature review (Nonaka & Takeuchi 1995; Davenport & Prusak 1998) that social communication and group knowledge creation is a continual process of the conversion between tacit and explicit knowledge (Nonaka & Takeuchi 1995). Tacit knowledge is personal, context-specific, and therefore hard to formalize and communicate. Explicit knowledge is also called “codified” knowledge and is transmittable in formal, systematic language. Nonaka and Takeuchi (1995) introduce knowledge conversion model which consists of four knowledge conversion processes. • Tacit to tacit knowledge conversion is called socialization. It is a process of sharing experiences and creating shared mental models. To successfully share mental models it is necessary to have at least some shared experience. • Tacit to explicit knowledge conversion is called externalization. It is a process of concept creation. It is triggered by dialogue or collective reflection. • Explicit to tacit knowledge conversion is called internalization. It is a process of embodying explicit knowledge into tacit knowledge – understanding the explicit knowledge. It helps if the knowledge is documented, because documentation helps individuals to internalize what they experienced. • Explicit to explicit knowledge conversion is called combination. It is a process of systemizing concepts into a knowledge system. Reconfiguration of existing information through sorting, adding, combining, and categorizing of explicit knowledge can lead to new knowledge. As requirement elicitation is knowledge-intensive process and its success depends on the effectiveness of knowledge sharing and creation among process participants it requires to be a continual process of conversion between tacit and explicit knowledge supporting all four knowledge conversion processes (Kirikova 2004) described above. And as such, requirement elicitation process requires using both formal and informal methods. During the socialization process participants (stakeholders and requirements engineer) learn to understand each other, learn about each other’s needs, expectations and wishes. The acquired knowledge becomes explicit conceptual knowledge through the externalization process. Acquired conceptual knowledge becomes as a guideline for creating systemic knowledge through combining different concepts
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expressed by different participants. Systemic knowledge (for example a diagram or system’s prototype) through the process of internalization creates new or changed understandings and expectations and often triggers a new cycle of knowledge creation. In a knowledge creation process through continual knowledge conversion, improvement of mutual understanding among participants and requirement (expressed concept) refinement occurs. Knowledge creation cycle ends when requirements engineer is satisfied with acquired systemized stakeholders’ requirements (see Fig. 3).
Fig. 3. Requirement elicitation as a cyclic knowledge conversion process
During the cyclic knowledge or requirement creation process, each participant’s mental models are changed, too, as learning is an important sub-process of knowledge creation. And each participant’s knowledge space (namely, cognition, emotion, motivation) is persistently affected, too. Continual knowledge conversion process cycle is necessary to avoid such requirement elicitation problems as misperception and disagreement. Requirement engineer needs to use both formal and informal methods to ensure that all participants’ conceptual systems are aligned. That means that mutual understanding and agreement regarding system requirements are achieved, as well as informally externalized requirements are correctly ‘translated’ into formal requirement specification.
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5 Conclusions Requirement elicitation is knowledge-intensive process and because knowledge is embedded in humans, requirement engineer needs to understand aspects affecting human knowledge. Modern requirements engineering approaches and methods tend to concentrate on user aspects. Such approach is, for example, User-Centred Requirements Engineering (Sutcliffe 2002), and such methods are, for example, Continual User Involvement, Agile Usage-Centered Design, the Planning Game (Hoffer et al. 2004). However, based on the literature review, we conclude that little attention has been paid to the processes occurring in the stakeholders’ minds and issues of how these processes affect success of requirement elicitation process. As requirement elicitation is knowledge-intensive process, its success depends on communication, collaboration, and understanding among process participants. The main problems caused by insufficient and unsuccessful communication are missing requirements, reluctant participation, misperception, and disagreement. Individual’s cognition, emotion and motivation affect each other and form a three dimensional space where individual’s knowledge is embedded. Besides that, humans are social beings; therefore individual’s knowledge is affected not only by his/her inner states but also by other individuals. Consequently, requirements engineer should use approaches and methods which positively affect all three dimensions of requirement stakeholder’ knowledge space, as well as support social communication and group knowledge creation. Such methods require being both formal and informal. And requirement engineer needs to be both analytical and intuitive to be able to understand and support stakeholders’ cognitive, emotional, and motivational processes, as well as produce formal requirement specification document. To support understanding, agreement and successful knowledge exchange among process participants continual process of the conversion between tacit and explicit knowledge is required (see Section 4). Therefore successful requirement elicitation method should support all four knowledge conversion processes: socialization, externalization, combination, and internalization. Successful knowledge conversion within a requirement elicitation process will ensure highly intensive knowledge exchange among process participants. That will improve mutual understanding and agreement regarding system requirements because of continual externalization/expression of individual knowledge and internalization/understanding of other participants’ knowledge which helps to align different conceptual systems as well as express one’s existing knowledge and come to know ideas. Successful knowledge conversion also ensures that informally externalized/expressed requirements are correctly ‘translated’ into formal requirement specification document. This requires using more formal and traditional knowledge combination approaches. The main contribution of this paper is to justify the importance of human aspects and necessity for combination of informal and formal approaches in requirement elicitation process. There are at least two important directions for the further research. The first is a need for better understanding of human mind and different aspects which affect human knowledge, communication, and collaboration. Such understanding will help to predict and avoid possible causes of problems which
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occur in requirement elicitation and other knowledge-intensive collaboration processes. The second area for the further research is comprehensive study and analysis of existent requirement elicitation methods to evaluate how well each of them support process participants’ cognitive, emotional, and motivational processes, as well as four knowledge conversion processes: socialization, externalization, combination, and internalization.
References Avison, D. E. & Fitzgerald, G. (2006) Information Systems Development: Methodologies, Techniques, and Tools. McGraw-Hill College; 4Rev Ed edition (March 1, 2006). Cockburn, A. & Highsmith, J. (2001) Agile Software Development: The People Factor. IEEE Computer, vol. 34, no. 11, pp. 131-133, Nov., 2001. Davenport, T.H. & Prusak L. (1998) Working Knowledge. MA: Harvard Business School Press. Davidson R. J., Goldsmith H. & Scherer K. R. (Eds.) (2003) Handbook of the Affective Sciences. New York and Oxford: Oxford University Press. Hoffer, J.A., George, J.F. & Valacich, J.S. (2004) Modern systems analysis and design. Prentice Hall; 4 edition. Isen, A. M., Daubman, K. A., & Nowicki, G. P. (1987) Positive affect facilitates creative problem solving. Journal of Personality and Social Psychology, 52, 1122-1131. Kirikova M. (2004) Interplay of tacit and explicit knowledge in Requirements Engineering. In New Trends in Software Methodologies, Tools and Techniques: Proceedings of the Third SoMet_W04, H.Fujita and V.Gruhn (Eds.), IOS Press, 2004, pp. 77-86. Li, K. Dewar, R.G. & Pooley, R.J. (2005) Computer-Assisted and Customer-Oriented Requirements Elicitation. In: Proceedings of the 13th IEEE International Conference on Requirements Engineering (RE'05) - Volume 00, Pages: 479 – 480. Meredith, R., May, D. & Piorun, J. (2000) Looking at Knowledge in Three Dimensions: An Holistic Approach to DSS Through Knowledge Management. Monashh DSS Lab Publication, http://dsslab.sims.monash.edu.au Nonaka, I. & Takeuchi, H. (1995) The Knowledge-Creating Company. New York, Oxford University Press. Ortner, J. (2002). Knowledge in an Electronic World?. In Karagiannis and U. Reimer (Eds.): Practical Aspects of Knowledge Management, 4th International Conference, Vienna, Austria, December 2002, Proceedings, pp. 281 – 300. Picard R. W. (1997) Affective Computing, The MIT Press. Polanyi, M. (1964) Personal knowledge: Towards a post-critical philosophy. New York: Evanston: Harper & Row. Richter-von Hagen, C., Ratz, D. & Povalej, R. (2005) Towards Self-Organizing Knowledge Intensive Processes. Journal of Universal Knowledge Management, vol. 0, no. 2, 148-169. Sloman, A. (2001) Beyond Shallow Models of Emotion. Cognitive Processing , 2(1), 178-198. Sommerville, I. (2004) Software Engineering. 7th ed., Pearson/Addison-Wesley, New York. Sun R. (ed.) (2006) Cognition and Multi-Agent Interaction. Cambridge University Press. Sutcliffe, A. (2002) User-Centred Requirements Engineering Theory and Practice. SpringerVerlag.
