Human-Computer Interaction and Presence in Virtual Reality

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Chapter 3 interactions and whether these meet the requirements of the cognitive processes of the user. At this detail level we cannot use the same model for the existing and the future situation, since these will have different implementation specific details. We will need two models: TM1 and TM2. Multi-modality Interaction in these applications uses multiple modalities. Users communicate with each other through use of the computer, and in this case also directly by talking. The computer responds to different types of inputs, such as the keyboard, joystick, but also headtracking, and produces output in different types of modalities such as vision, sound or even haptics. These modalities cannot be viewed separately; they are co-dependent and influence one another. We therefore need a method that can model these modalities. Again, the Language / Action Perspective looks promising since it considers communication in different modalities to be equal. However, different modalities might afford different possibilities for communication and we should therefore look at which modality is used for which type of communication, possibly similar to the CUD. Level 1 Level 2 Level 3 Modelling User Cognition Modelling the UI Modelling Tasks Pragmatics Semantics Knowledge User(s) Computer(s) Cognitions Syntax Lexicon User Interface Tasks Domain Objects Figure 3.5 shows what part of the potential domain of TA is covered by the various discussed methods. Most TA methods limit themselves to detail level 1 and 2. The reason for this is that in reality users perform a great number of tasks that are interrelated, but these tasks themselves are often straightforward and uncomplicated. An HCI-designer is therefore Goals Media Objects Figure 3.5: Domains of the various TA methods as subsets of the complete potential domain of TA. best served with an overview of all the tasks that need to be supported. In VRET there are a limited number of tasks being performed by the users, however, these tasks are of a complex nature, taking place in a close collaborative setting and requiring communication over various modalities. This requires a detail analysis of how tasks are performed, requiring a TA of detail level 3. There are several TA methods that cover part of this detail level, but none that can show a complete picture of how the system and the users 26
Analysis influence each other. To best facilitate the design of user interfaces for VRET, we will most likely need a combination of the existing methods at level 3. 3.3 Adapting existing TA methods Similar to most TA methods, we can include a task hierarchy into our analysis. This will allow us to include low-level details of the implementation and place these into the context of structures at a higher level of abstraction. Because we are looking explicitly at the implementation level of our work situation, it is a good idea to create a distinction between those parts of the task hierarchy that are dependent on the current task implementation and those that are not and should therefore hold for other task implementations as well. The definition of the various tasks and actions could be performed arbitrarily, at the analists discretion. However, to ensure that the analysis becomes less dependend on the individual analist, an existing framework can be used. One such framework that can be applied in this case is the Language / Action Perspective By viewing the interaction as part of a conversation between users and the computer, we can incorporate the collaborative aspects of these types of applications. Using speech act theory, we can categorize the actions of users and computers in several categories. (Habermas, 1981; Dietz & Widdershoven, 1991): • Imperative: ordering the listener to perform an action, usually implicitely stating that the speaker holds the power over the listener to demand this action. • Constative: commit the speaker to something being the case - to the truth of the expressed proposition • Regulative: either requesting the listener to perform a certain action, or promising that the speaker will perform an action. • Expressive: express a psychological state about a state of affairs (e.g., apologizing and praising) These categories can help in identifying the lowest level of our task hierarchy and can aid in defining these tasks in an objective fashion, in other words, making the particular choice of definitions independent of a particular analyst. Speech acts are not unrelated events, but participate in larger conversational structures (Floris & Ludlow, 1981). An analysis of the sequence in which events occur can provide insight into the typical structure of a therapy session. Several methods exist for uncovering the sequence of events in human-computer interaction. The most commonly used are cognitive analysis and graph-matrix analysis (McGrew, 1997). As will become clear later on, the interaction in VRET systems is of such an unpredictable nature that cognitive analysis, where the observer must aggregate, analyze and abstract the task structure, is not very suitable. The more quantitative approach of graph-matrix analysis can be used in this case. The advantage of a task hierarchy is that we can use it to check whether a design meets all functional requirements. We can do this by determining whether all high level implementation-independent goals are supported by lower level tasks and whether these tasks can be performed with the actions available to the user. However, we are also interested in how implementation specific details affect the HCI and for this we will first need a closer look at the way users interact with systems, and especially at the user’s cognitions. 27
Page 1: Human-Computer Interaction and Pres
Page 4 and 5: Dit proefschrift is goedgekeurd doo
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Page 11 and 12: 1 Introduction Human Computer Inter
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Page 27 and 28: 3 Analysis As stated in the previou
Page 29 and 30: Analysis 3.1.3 Agoraphobia In an ex
Page 31 and 32: Analysis works (Benyon & Imaz, 1999
Page 33 and 34: Analysis actors. Besides this, Cont
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Page 39 and 40: Analysis 3.3.3 State information No
Page 41 and 42: Analysis Unfortunately, this will m
Page 43 and 44: Analysis Name system URL website Ph
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Page 55 and 56: Goals Procedures Sound T.Controls T
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Presence because the situations tha
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Presence usability are focused on t
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Chapter 5 locomotion technique suit
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Chapter 5 a base transmitter that g
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Chapter 5 3. Gaze-directed: This te
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Chapter 5 content of labels distrib
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Chapter 5 Measures Prior to the exp
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Chapter 5 Unstandardized Coefficien
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Chapter 5 phobia that often involve
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Chapter 5 subjects were all diagnos
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Chapter 5 VE does show a significan
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Chapter 5 possible explanation coul
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Chapter 5 Large drop Large drop A2
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Chapter 5 5.5.2 Results Subjects Mi
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Chapter 5 the SUD scores in the dif
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Chapter 5 The third experiment clea
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6 Therapist's user interface The UI
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6.2.1 SUDs recording During therapy
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Therapist’s user interface Figure
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Therapist’s user interface The st
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Therapist’s user interface The 2D
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Therapist’s user interface Heartr
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Therapist’s user interface • To
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Therapist’s user interface elemen
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7 Conclusions In this dissertation
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7.1.2 Determining the patient's fea
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Conclusions patient control allowed
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Conclusions Guideline 5: A tool for
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References Alcaniz , M. Banos , R.M
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References Dietz, J.L.G., Widdersho
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References Hodges, L., Rothbaum, B.
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References Lombard, M., Ditton, T.(
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References Reeves, B., Nass, C. (19
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Slater, M. (1999). Measuring Presen
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References van Welie, M. (2001) Tas
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UED User Environment Design VE Virt
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Appendix A Complaints and wishes 'F
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Appendix A A.4 Experiment 3 Compute
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Appendix A 3. Were you able to see
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Appendix A 28. 'If you had to choos
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Appendix B Element: Instruct patien
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Appendix B Element: Inform patient
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Appendix B Element: Listen for resp
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De TA methode is getoetst door deze
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Curriculum vitae Martijn Schuemie w
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2000-1 Frank Niessink (VU) Perspect
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2002-09 Willem-Jan van den Heuvel(K
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