User Interface Design and Ergonomics - National Open University of ...

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Determine time of each operation (based on the table below) Determine if operation times should be adjusted (slower for elderly, disability, unfamiliarity, etc.) Sum up execution times Iterate as needed and check with prototyping if possible Studies into this field were initially done by Card, S.K., Moran T.P., & Newell, A. Current studies in the field include work to distinguish process times in older adults by Tiffany Jastrembski and Neil Charness (2007). Table 1 shows some of the results from the work Parameter Mean Range Eye movement time 230 ms 70-700 ms Decay half-life of visual image storage 200 ms 90-1000 ms Visual Capacity 17 letters 7-17 letters Decay half-life of auditory storage 1500 ms 90-3500 ms Auditory Capacity 5 letters 4.4-6.2 letters Perceptual processor cycle time 100 ms 50-200 ms Cognitive processor cycle time 70 ms 25-170 ms Motor processor cycle time 70 ms 30-100 ms Effective working memory capacity 7 chunks 5-9 chunks Pure working memory capacity 3 chunks 2.5-4.2 chunks Decay half-life of working memory 7 sec 5-226 sec Decay half-life of 1 chunk working memory 73 sec 73-226 sec Decay half-life of 3 chunks working memory 7 sec 5-34 sec Table 1:- Processor actions’ times 3.1.1 Potential Uses Once complete, the calculations can then be used to determine the probability of a user remembering an item that may have been encountered in the process. The following formula can be used to find the probability: P = e -K*t where K is the decay constant for the respective memory in question (working or long term) and t is the amount of time elapsed (with units corresponding to that of K). The probability could then be used to determine whether or not a user would be likely to recall an important piece of information they were presented with while doing an activity. It is important to deduce beforehand whether the user would be able to repeat the vital information throughout time t, as this has a negative impact on the working memory if they cannot. For example, if a user is reading lines of text and is presented with an important phone number in that text, they may not be able to repeat the number if they 62
have to continue to read. This would cause the user’s working memory’s decay time to be smaller, thus reducing their probability of recall. 3.2 PERCEPTION In philosophy, psychology, and the cognitive sciences, perception is the process of attaining awareness or understanding of sensory information. It is a task far more complex than was imagined in the 1950s and 1960s, when it was predicted that building perceiving machines would take about a decade, a goal which is still very far from fruition. The word comes from the Latin words perceptio, percipio, and means "receiving, collecting, action of taking possession, apprehension with the mind or senses. Perception is one of the oldest fields in psychology. What one perceives is a result of interplays between past experiences, including one’s culture, and the interpretation of the perceived. If the percept does not have support in any of these perceptual bases it is unlikely to rise above perceptual threshold. Two types of consciousness are considerable regarding perception: phenomenal (any occurrence that is observable and physical) and psychological. The difference everybody can demonstrate to him- or herself is by the simple opening and closing of his or her eyes: phenomenal consciousness is thought, on average, to be predominately absent without sight. Through the full or rich sensations present in sight, nothing by comparison is present while the eyes are closed. Using this precept, it is understood that, in the vast majority of cases, logical solutions are reached through simple human sensation. Passive perception (conceived by René Descartes) can be surmised as the following sequence of events: surrounding → input (senses) → processing (brain) → output (reaction). Although still supported by mainstream philosophers, psychologists and neurologists, this theory is nowadays losing momentum. The theory of active perception has emerged from extensive research of sensory illusions, most notably the works of Richard L. Gregory. This theory, which is increasingly gaining experimental support, can be surmised as dynamic relationship between "description" (in the brain) ↔ senses ↔ surrounding, all of which holds true to the linear concept of experience. In the case of visual perception, some people can actually see the percept shift in their mind's eye. Others, who are not picture thinkers, may not necessarily perceive the 'shapeshifting' as their world changes. The 'esemplastic' nature has been shown by experiment: an ambiguous image has multiple interpretations on the perceptual level. The question, "Is the glass half empty or half full?" serves to demonstrate the way an object can be perceived in different ways. Just as one object can give rise to multiple percepts, so an object may fail to give rise to any percept at all: if the percept has no grounding in a person's experience, the person may literally not perceive it. The processes of perception routinely alter what humans see. When people view something with a preconceived concept about it, they tend to take those concepts and see them whether or not they are there. This problem stems from the fact that humans are 63
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] NATIONAL OPEN UNIVERSITY OF NIGER
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National Open University of Nigeria
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Summary ...........................
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UNIT 3 - GRAPHICAL USER INTERFACE (
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Assignments File Tutor-Marked Assig
Page 12 and 13: 2 DESIGN and DESIGNING GOOD USER IN
Page 14 and 15: need both the study unit you are wo
Page 16 and 17: CIT 711: USER INTERFACE DESIGN AND
Page 18 and 19: UNIT 1 FUNDAMENTALS OF USER INTERFA
Page 20 and 21: 3.3 TYPES OF USER INTERFACES Curren
Page 22 and 23: 3.5 USER INTERFACE MODALITIES AND M
Page 24 and 25: Table of Contents 1.0 Introduction
Page 26 and 27: 3.1.1 DESIGNING A GOOD USER INTERFA
Page 28 and 29: widgets properly is to read and und
Page 30 and 31: Figure 1:- Showing that alignment o
Page 32 and 33: 6.0 TUTOR MARKED ASSIGNMENT a. How
Page 34 and 35: A graphical user interface is a typ
Page 36 and 37: Operating System. It is easy for a
Page 38 and 39: A list of items from which to selec
Page 40 and 41: collaborative work. For example, sc
Page 42 and 43: MODULE 1 UNIT 4 HUMAN COMPUTER INTE
Page 44 and 45: 3.3 DIFFERNCES WITH RELATED FIELDS
Page 46 and 47: window blinds to automobile braking
Page 48 and 49: Wickens, Christopher D., John D. Le
Page 50 and 51: The International Ergonomics Associ
Page 52 and 53: approach, the Gilbreths reduced the
Page 54 and 55: 3.6 BENEFITS OF ERGONOMICS The thre
Page 56 and 57: Another key to reducing lumbar disc
Page 58 and 59: MODULE 2 - USER INTERFACE DESIGN TE
Page 60 and 61: methods include inspection methods,
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Page 68 and 69: Motor skill which is a learned seri
Page 70 and 71: MODULE 2 UNIT 2 UNDERSTANDING USERS
Page 72 and 73: The users of a system must be ident
Page 74 and 75: This example brings up an important
Page 76 and 77: whether you want to have a palette
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Page 80 and 81: MODULE 2 UNIT 3 USER CENTERED DESIG
Page 82 and 83: or small body text is also hard to
Page 84 and 85: Introduction to User-centered desig
Page 86 and 87: organizations themselves. Interacti
Page 88 and 89: After thorough analysis using vario
Page 90 and 91: Interaction design which is the dis
Page 92 and 93: In human-computer interaction and c
Page 94 and 95: The preferred method for ensuring u
Page 96 and 97: 3.4 ISO STANDARDS FOR USABILITY ISO
Page 98 and 99: In this unit, you have been introdu
Page 100 and 101: affect the way the command is execu
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Page 104 and 105: The term direct manipulation was in
Page 106 and 107: There are two important reasons for
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Page 110 and 111: UNIT 1 PROTOTYPING Table of Content
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Figure 12: The iterative steps of p
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select print Figure 13: An interfac
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Ambler, S.W. & Constantine, L.L. (2
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3.2 LOW-FIDELITY PROTOTYPES Low-fid
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Figure 14:- Example of Sketching II
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Much more important for features th
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DENIM, an extension of SILK, is a t
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• Encourage menu & forms style, r
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Another problem is that native widg
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interfaces, so that a realistic sim
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UNIT 3 INPUT AND OUTPUT MODELS Tabl
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Recall that perceptual fusion means
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3.2 OUTPUT MODEL There are basicall
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directly-mapped pixel image will no
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Most stroke models also include som
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UNIT 4 MODEL VIEW-CONTROLLER (MVC)
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3.3.2 AS A DESIGN PATTERN MVC enco
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The Views are XForms controls for s
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UNIT 5 LAYOUTS AND CONSTRAINTS Tabl
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3.5 CONSTRAINTS Constraints are rel
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MODULE 4 UNIT 1 TECHNIQUES FOR EVAL
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a. Card Sorting Card sorting is a w
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Rapid prototyping is a method used
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3.2.1 THE USE OF PROTOTYPES It is o
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Dumas, J.S. and Redish, J.C. (1999)
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the users' respect for you as a pro
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the users will be and what kind of
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speed whenever the average load was
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Table 4:- Table: Average times for
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phases: list the actions, and then
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Nielsen and Molich used their own e
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7.0 REFERENCES AND FURTHER READING
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users. If you do not, you can be ba
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If you are led to develop more and
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It's very easy to shape the comment
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a. Analyzing the Bottom-Line Number
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you use. But then you need some way
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ecruit test users with more similar
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MODULE 4 UNIT 4 OTHER EVALUATION IS
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3.2 CURRENT ISSUES CONCERNING EVALU
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2.0 OBJECTIVES By the end this unit
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It provides a real focal point for
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3.3.4 CONDUCTING THE TEST Having co
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The stages involved in usability te
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