U-M CIS 375 - User Modeling
Course Cis 375-
Pages 28

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User ModelingWhat is HCI?User interface involvesTypical Human Factors MeasuresWhere do user interfaces come from?HCI Goals for DesignersMotivation for Including Human Factors in User Interface DesignAccommodating Human Diversity in DesignUS Military Standards for Human Engineering and DesignHow is this done?Approaches to User Interface DesignKeystroke Level Model (KLM)Standard Execution TimesCurrent Design: Delete a file by dragging it to the trash iconNew Design: Adding a command to menuAssumptionsInserting Mental Operators: Where does the user stop and think?Mental Operators New vs Experienced UsersDelete a file by dragging icon to trashPlacement of Mental OperatorsGOMS Model Goals Operators Methods Selection RulesUser GoalsPowerPoint PresentationSlide 25Generalized MethodsSub MethodMethod for GOMS Model Construction1User ModelingCIS 375Bruce R. MaximUM-Dearborn2What is HCI?•Answer: human computer interaction•Not just human factors•No strong agreement•Main emphasis of HCI is user interface design3User interface involves •Hardware•Behavior of software•Supporting documentation4Typical Human Factors Measures•Time to learn• Speed of performance• User error rates• Retention over time• Subjective satisfaction5Where do user interfaces come from?•Designed by programmers•Functionality dominates software design and marketing•Designer intuition is often used rather than user modeling (not good)6HCI Goals for Designers•Improve user's quality of life by building quality (not flashy) interactive systems•Promote attention to user interface issues which should be considered by managers•Become successful designers of systems that go beyond intuitive concepts like "user friendliness" and focus on supporting the user's real task goals7Motivation for Including Human Factors in User Interface Design•Life critical systems•Industrial and commercial uses•Personal applications•Exploratory, creative, and cooperative systems8Accommodating Human Diversity in Design•Physical workspaces•Cognitive and perceptual ability differences•Personality differences•Cultural and international diversity•User disabilities•Elderly users9US Military Standards for Human Engineering and Design•Achieve required performance•Minimize personnel training requirements•Achieve required reliability•Foster design standardization10How is this done?•Ensure functionality by basing design on user task analysis•System reliability requires designer attention to details like privacy, security, and data integrity•Standardization requires attention to issues like system integration, consistency, and portability•Schedule and budget must allow for human factors work like user analysis and testing11Approaches to User Interface Design•Human Factors: prototype and test•Cognitive theory: production system• Engineering models:–KLM keystroke level model–GOMS Models goals, operators, methods, selection rules12Keystroke Level Model (KLM)•Choose representative user task scenarios•Specify design to point that keystrokes defining actions can be listed•List keystrokes (operators) required to perform task•Insert mental operators at points user needs to stop and think•Look up standard execution time for each operator•Add up the execution times for the operators•Total is estimated time to complete task13Standard Execution Times•K - key press (0.2 sec = 55 wpm)•P - point with mouse (1.1 sec)•B - mouse button press (0.1 sec)•BB - press and release button (0.2 sec)•H - home hands to keyboard or mouse (0.4 sec)•M - mental act of thinking (1.2 sec)14Current Design: Delete a file by dragging it to the trash icon1. Point to file icon (P)2. Press & hold mouse button (B)3. Drag file to trash icon (P)4. Release mouse button (B)5. Point to original window (P) 3P + 2B = 3.5 sec.15New Design: Adding a command to menu1. Point to file icon (P)2. Click button (BB)3. Point to file menu (P)4. Press and hold button (B)5. Point to delete command (P)6. Release mouse button (B)7. Point to original window (P)4P + 4B = 4.8 sec.16Assumptions•These previous scenarios work only work if the user is currently able to view all the needed windows and icons.•If the trash icon for example is buried under other windows the first procedure is slowed down quite a bit.17Inserting Mental Operators: Where does the user stop and think?1. Initiating a process.2. Making strategic decisions.3. Retrieving a chunk from user’s short term memory4. Finding something on the screen.5. Verifying intended action is complete.18Mental Operators New vs Experienced Users•New users stop and check feedback after every step•New users have small chunks•Experienced users have elaborate chunks•Experienced users may overlap mental operators with physical operators19Delete a file by dragging icon to trash1. Initiate delete. (M)2. Find file icon. (M)3. Point to file icon. (P)4. Press & hold button. (B)5. Verify icon reverse video. (M)6. Find trash icon. (M)7. Drag file to trash icon. (P)8. Verify trash reverse video. (M)9. Release button. (B)10. Verify bulging trash icon. (M)11. Find original window. (M)12. Point to window. (P)3P + 2B + 7M = 12.6 sec.20Placement of Mental Operators•Hard to do - requires good intuition from designer•Consistency in the number of Mental's assigned is more important than their exact positioning21GOMS ModelGoals Operators Methods Selection RulesAdvantages•GOMS models are executable•GOMS models allow simulated execution of user task•Provide a rigorous description of what user must learn•Provide estimate of size or complexity of interface (number of distinct methods and their length)•Can estimate both learning time about 30 sec per step and execution time (total of KLM operators)•Allow designer to evaluate the effect of reusing or sharing methods among several tasks22 This example is extracted from:David Kieras, A Guide to GOMS Task Analysis, University of Michigan Technical Report, Spring, 1994.23User Goals•Delete a file.•Move a file.•Delete a directory.•Move a directory.24To accomplish goal of deleting a file:1. Accomplish goal of dragging file to trash.2. Return with goal completed.To accomplish goal of moving a file:1. Accomplish goal of dragging file to destination.2. Return with goal completed.25To accomplish goal of deleting a directory:1. Accomplish goal of dragging directory to trash.2. Return with goal completed.To accomplish goal of


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U-M CIS 375 - User Modeling

Course: Cis 375-
Pages: 28
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