The Story So Far ...
HCI Course Contents

* * * Under Gradual Construction * * *

Map	Topics	Book
	Reverse Engineering First: Self assessment sheet Main topic: If this web page was the result, what were the Requirements?	--
	Introduction to HCI Class business -- books, ..., minor forms, ... Web pages Class mailing list Yesterday's experience... Project 1 Projects and class provide experiences as well as facts KISS Choice of material Reminder: Show the video! Course goals/outcomes -- what you'll see/do/learn Small design decisions have major effects on users Technology isn't the primary concern Sensitivity to HCI issues is key You need to confirm the "obvious" What's HCI? HCI has contributions from many areas (eg. CS, Psych., Art, AI, etc.) "It's Obvious!" Really? needs knowledge, trade-offs, experiments. It's about "Design" -- algorithms + software eng + interfaces Design factors -- incl. user, task, hardware, interaction, ... Goals for a good User Experience list Goals for Usability list They must be measurable! (i.e., metrics) How are these goals related? Normal people vs CS Majors Extensive computer knowledge/experience leads to different abilities and expectations We're not normal! The moral: design for users and their task, not yourself	--
	Models of Design HCI is mostly concerned with the Design of interfaces. Models of Design Identify Needs, Establish Requirements (with User & Task Analysis) Developing Alternative Designs (Conceptual, Physical) Build Interactive Versions of Designs (prototyping) Paper Prototype; Rough Computer Prototype; Detailed Prototype vary by Materials - e.g., paper, computer, special device. Resolution/level - e.g., simplified sketch, screens, final product. Scope - e.g., single feature, feature subset, full set. e.g., Paper prototyping Evaluation (Metrics, Questionnaires, Interviews, Heuristic Evaluation, etc.) Decide, evaluate, decide, evaluate, decide, evaluate, ... Design Ingredients: needs, requirements, constraints, preferences, evaluation criteria. Multidimensional search in a Search Space. Generate many alternative conceptual designs, then evaluate and select. Least commitment Make Evaluation Criteria explicit & measurable, with importance. Concept scoring matrix Understand uncertainty of evaluation Design models: waterfall, spiral, star, ...	Models: Figs 1.8, 1.9, 1.10; Conceptual design: ch8.
	HCI tasks & Metrics What gets produced/used by HCI professionals? Theories, Principles & models (i.e., what people do in different situations & why; how they process information; best practices; ...) (e.g., Universal Principles of Design) Guidelines for interface design Analysis & evaluation of empirical data -- design & carry out experiments * gather data * i.e., a design choice produces what effects? -- analysis to find patterns/features * hypotheses by induction (using data) * or confirm a given hypothesis -- evaluation to determine quality -- e.g., evaluation by usability testing Does it meet the interface design requirements? Invent/Design/Use Software-based methods -- menus, forms, commands, messages, ... -- use of sound, graphics, animation, speech, ... -- interaction techniques Invent/Design/Use Hardware-based methods -- keyboards, displays, other devices -- e.g., eye tracking; "mole"; ... Tutorials, manuals, demonstrations Design elements: icons, layouts, color schemes Questionaires (e.g., determine user's satisfaction) Growth of number of devices with interfaces (examples???) -- makes HCI more vital. + -- responsive design +: sharing an interface across devices (issues???) Remember, HCI is about Human Performance Poor interfaces cause...??? General goals for interface development -- deliver functionality!        -- discover by task analysis    e.g., action frequencies; too many/few functions -- avoid & respond to potential errors -- others    (e.g., portability, standardization, reliability, consistency, ...) -- still more goals make it very hard! -- need to make trade offs: e.g, consistency versus...? The basic Metrics: Speed of performance Rate of errors by user Time to learn Retention over time Subjective Satisfaction Other metrics??	Ch.2 Metrics: Ch.6, 21 Table 3.1
Map	Human diversity What is Human diversity? Can we dilute the effects of diversity? Reduce diversity - e.g., training Reduce demands on user - e.g., less information displayed; meet expectations Reduce sensitivity - e.g., make interface more tolerant to user input variation Increase adjustability - e.g., customization Offer variety - e.g., versions for experts, and novices; languages Consider the whole "system": ENVIRONMENT-->USER-->INTERFACE-->SYSTEM Environmental factors affect people's interface use -- what effects do each factor have? (on people and interface) Dirt (e.g., Norton abrasives) Noise levels (and vibration) (is communication needed?) Environment Background Illumination levels (glare) Illumination on display (& flicker of display) Air quality & movement Temperature & humidity Electromagnetic pollution Space -- Can you move well? Do you need to? Sight lines? Safety of environment. Examples??? Interruption (e.g., loud noises, flashes, smells, alarms) Effect??? Design workspace & interface to compensate for environment! USER-->INTERFACE-->SYSTEM User Differences ("know the user"!) - User Analysis How/why do different people react to the interface? (and environment) Diversity: what differences between people are important? What if the user were...     Chinese, left handed, short sighted, 92, very tall, an artist? Abilities: e.g., perceptual, memory, cognitive, motor, physical,... Human Mental & Physical abilities map to design requirements & constraints! --- N.B., lack of abilities correspond to limitations Physical factors: e.g., size & reach importance? keyboard, screen, other devices... why not design for average person??? -- so how do you handle that??? static measurements not enough, Why??? -- e.g., speed, force, accuracy of mvt., endurance, reaction. ergonomics -- work surfaces, chairs, controls, ... interaction of IMGD & Robotics with these issues??? Social factors Interruption Privacy Collaboration Social interaction vs. isolation Personal space Trade-offs???	Ch.3, Ch.4, Table 4.4
	Abilities: Perception, Memory, Cognition More about "Abilities"... Perception & Cognition ("know the user") Reaction time -- simple reaction; -- hands faster than feet -- choice reaction; -- depends on stimulus-response compatibility. "The degree to which what people perceive is consistent with the actions they need to take." -- example of good and bad??? -- e.g., stimulus-response compatibility for driving Visual system acuity; e.g., highway fonts impact of lighting/flicker; perception of depth (light from above) -- why useful??? Motion Induced Blindness Touch -- why relevant??? Hearing -- range of frequencies Factors affecting perception & cognition -- emotional arousal (fear/stress vs. errors); -- mental load (read while counting backwards); -- attention. Model Human Processor (also at) (STM, LTM, Chunking, Processors) types of memory (VIS, AIS, STM/WM, LTM) STM: chunking, decay time & 5-9 chunk capacity. Perceptual Processor -- cycle time -- role in perception of movement (e.g., film) Cognitive Processor -- recognize-act cycle. Motor Processor -- discrete control of movement.	Ch.3
	Perception, Memory, Cognition (continued) Principles of Operation (handout) Fitts Law -- predicts time to move hand -- sensitive to distance moved and target size -- "bit" = amount of information (reduces uncertainty). Power Law of Practice -- predicts time to do task -- practice improves performance -- has lower bound. Hicks Law -- choice reaction -- time increases with uncertainty -- assumes equally probable alternatives -- consider the buttons under lights example. Rationality Principle -- rational action is the best given current knowledge -- influenced by      Goals, Task, Operators, Inputs,      Knowledge, Process-limits. Problem Space Principle -- "design space" is an example. Personality & culture Human Diversity -- personality & cultural ("know the user") Personality types -- introvert/extrovert, MBTI, risk & uncertainty avoidance, locus of control (test) Cultural (linguistic, icons, formats, formality, ...) Cultural dimensions and global Web user-interface design + Linguistic -- alphabets, words, syntax (verb position) -- Yummy! Pocari Sweat -- reading/writing direction      impact of L-to-R & Top-to-Btm ???? * the F Pattern for eye scanning Icons (covered later) Standard formats -- US vs. UK date (24th September 1987) -- order of items in an address -- names (e.g., Li Xiang and Brown David) Formality & respect Other User Issues Disabilities -- Introduction to Web Accessibility e.g., use of CAPTCHA with bad eyesight? Elderly + -- senses, motor, memory, ... ??? large buttons? large spaces between buttons? Mobile phone design for older persons + Speech recognition and alternative interfaces for older users + Font choice, bad eyes and reflective materials +	Ch.3, 9 App.3
Map	T/P/G/M intro. & User Models Theory, Principles, Guidelines, Models What's a Theory? an organized, well tested system of accepted knowledge that applies in a variety of circumstances to explain or predict a specific set of phenomena. what are the key words in that definition??? why is a theory useful??? What's a Principle? A basic generalization that is accepted as true and that can be used as a basis for reasoning or conduct. e.g., "Relationships and patterns between variables can be detected easily by allowing comparisons." Design Principles User Interaction Design Principles + why are Principles useful??? What's a Guideline? A rule that provides guidance to appropriate behaviour. A rule of thumb, i.e., usually helpful The essence of experience e.g., "Respect the rules of human conversation" Sample Guidelines Note 'style guidelines'. why are guidelines useful??? What's a Model? A hypothetical description of a complex entity or process. Often describes structure, behavior and/or function e.g., Four level model (below) Have we seen one recently? why are models useful??? Some models: Taxonomies -- the simplest model -- provides types/classes, ordering & grouping -- e.g., types of user -- why is it useful??? Four level model -- conceptual, semantic, syntactic, lexical -- useful for design or evaluation Conceptual level -- designer's (intended) model of system. Semantic level -- meanings (e.g., of I/O, of icons, ...) Syntactic level -- structure of items on screen Lexical level -- primitive ingredients (e.g., icons, windows, prompts, ...) Connection between Conceptual Model & User's Mental Model (slide). What the designer wants the user to think about how the system works versus what users actually do think about how the system works! Guidelines for Designing Conceptual Models Sample mental model -- changing text size in browser. User's Mental model -- incomplete, hard to run, unstable, no firm boundaries, etc. -- can be structural model (how it works) -- can be functional model (how to use it) -- allows user to try to predict & interpret system action. Mental models can dramatically change expectations e.g., Scrolling Text in window example/experiment Model 1 - scroll bar indicating direction of window's text movement. Model 2 - scroll bar indicating what part of the window's text you want to see.	Ch.5, 4, 9
	GOMS, keystroke model; Seven stages Evaluation using predictive models Predictive -- of what? e.g., time, errors, ... GOMS model -- Goals, Operators, Methods, Selection rules Goals (& subgoals) -- what user wants to achieve (e.g., delete word) Operators -- small things the user does while using interface -- "elementary perceptual, motor or cognitive acts" -- operators change user's mental state or the world Methods -- procedures used to accomplish goal -- e.g., delete a word. -- built from Operators -- may include tests on user's memory or task environment, that determine choice of operators. Selection rules -- rules used to select method(s) -- e.g., how many methods to delete a word??? pick best. Transition Networks state transition networks. e.g., finite state automata. states and the actions that cause state change (diagram). can be used to describe Methods. can be used to model interfaces in general. (ready state)----delete-key--->(delete state) Shopping cart example Keystroke Level Model -- predictive, detailed model based on GOMS -- time to carry out task of (mainly) text input -- Model's parts: keys, pointing, homing, draw, mental, SRT -- they're all durations. TK = Keystroke or button push TP = Positioning or pointing TH = Homing (mvt. between devices) TD = Drawing TM = Mental preparation TR = Response time of system (user waits) Mentally prepare (M) 1.35 Reach for Mouse (H) 0.40 Position mouse (P) 1.10 Click mouse (P1) 0.20 Move hands to keys (H) 0.40 Mentally prepare (M) 1.35 Type "n" (K) 0.22 Type "o" (K) 0.22 Type "t" (K) 0.22 Type " " (K) 0.22 ------------------------------------- Total predicted time 5.58 seconds Norman's 7 stages of user action model i.e., the "Human Interaction Cycle" or "Human Action Cycle" Guides how we (HCI designers) think about user interaction General version Norman's version: Loop through... Forming Goal Forming Intention (plan of actions) Specify Action Execute Action ...............System action..................... Perceive Result of Action Interpret Result Evaluate Outcome stage 3 & 4 affect Interaction design stages 5 & 6 affect Information design Opportunities for errors: Gulf of Execution; Gulf of Evaluation Gulf story + Gulf of Execution: mental distance between what needs to be achieved, and the series of steps that must be taken make it happen. Gulf of Evaluation: mental distance between the data presented on the device's interface and useful information required for decision-making. Interface Evaluation based on possible user actions/errors at each part of cycle. What are examples of errors caused at levels 4 and 5 for example???? Design Interface to aid user's actions at each part of cycle. e.g., alternative actions should be visible Focus on each part of cycle separately.	Ch.10
	Feedback; Consistency; Syntactic & Semantic Knowledge Feedback (Principle) vital! small scale & large scale examples ??? if none or delayed ??? within expected time period? when is user willing to wait? feedback during long delays? -- 2 seconds in human conversation -- 0.1 to 10 seconds related to Norman's 7 stages of user action ??? Consistency (Principle) e.g., of naming, order, action, icons, ... consequence: affects user's expectations -- why important ??? consequence: could learn from a single example -- why important ??? Use of a grammar (rules) for syntax Consistency leads to few rules Fewer rules, easier to learn Examples for naming, order, action, icons ??? Modelling User's Knowledge Four level model again -- conceptual, semantic, syntactic, lexical Before, we were modeling the interface It can also be a model of what the user needs to know There's an impact on user learning Syntactic knowledge -- structure: order, layout, grouping, symmetry -- low level details -- many details -- hard to learn & easy to forget -- small variations lead to problems --- S = Save or Send ? --- To From or From To order ? -- try to avoid/reduce/hide! Semantic knowledge -- Computer Concepts & Task Concepts -- each has Actions & Objects -- i.e., four categories (CC.A, CC.O, TC.A, TC.O) These concepts introduced by designer's conceptual model. These concepts form "expectations" -- why important??? Computer concepts ??? (actions & objects) -- "normal" people may have trouble with them. -- if visible then should match task concepts well. Task concepts ??? (actions & objects) -- "normal" people should know them. Impact of strong vs. weak knowledge and task vs. computer semantic knowledge -- what kind of person? -- what do they need to help them perform well?	Ch.4, 9
Map	User analysis, Task analysis "Know the User" -- User Analysis (UA) User Profile Checklist -- plus other items if appropriate (e.g., IQ, RT) Novice -- how to define??? -- how to recognize??? -- what do they know??? -- what do they need??? Intermittent -- how to define??? -- how to recognize??? -- what do they know??? -- what do they need??? Expert -- how to define??? -- how to recognize??? -- what do they know??? -- what do they need??? Accelerators (for Experts) Macros Abbreviations Shortcuts through information (such as menus) Denser presentation of information Customization (how, when????) -- helps put the user in control "Know the Task" -- Task Analysis (TA) Tasks & subtasks Task action grouping Task action sequences Task frequencies why do we care??? note 80-20 rule (slide) List Task Actions & Task Objects Appropriate level for atomic user actions? Match user actions to task actions Output of TA Objects/artifacts used Use cases that describe user's work Results from cognitive walkthrough -- relates to human action cycle Any "work arounds" used All other task information (see above) "Know the Domain" -- what does the user need to know about the domain? -- how can the interface help? "Know the Enviroment" -- how might the environment affect the use of the interface? -- physical and social issues -- how can the interface help? Start Design Process... Collect general Requirements (+ve) & Constraints (-ve) regarding: users task domain environment social/organizational setting usability find explicit constraints, preferences, trade-offs Build Conceptual Model -- e.g., a Content Diagram -- remember Guidelines for Designing Conceptual Models i.e., what kind of mental model do you want the user to have? Select Interaction Style and relevant Interaction Design + issues. Identify all other relevant principles +, guidelines, models and metrics. Make prototypes (low/high fidelity, partial/complete scope) Evaluate! Refine and repeat...	Ch.3, 4, 6, 11
Map	Interface Evaluation:       ... Principles and Rules for Evaluation (but also Design) Check Principles+ from Psychological p.o.v. Users see what they expect to see -- especially when rushing/stressed/distracted -- generate and reinforce expectations (How ???) principle of Consistency principle of exploiting Prior Knowledge -- use metaphors (e.g., calculator) -- use task knowledge Users can't easily focus on more than one activity at a time -- but many have to: guide the user principle of Perceptual Organization (grouping) principle of Importance -- prominence: position/size/color/fading/overlap... It's easier to perceive a structured layout law of Proximity (relationships) law of Similarity (relationships) law of Closure (fill the gap) law of Continuity (lines of dots) law of Symmetry (suggests grouping) -- men think asymmetry is worse than women do Figure-ground (cows, dogs & zebra) It's easier to recognize than to recall principle of Recognition -- don't make the user remember Check Principles+ from Design p.o.v. principle of Simplicity -- natural, simple subtasks, uncluttered (KISS) -- note that everything on the screen provides information,      so don't make them have to filter stuff out! principle of Structure -- grouping, layout (for Task) principle of Consistency -- uniformity, fewer rules, learnability, reuse of kn. principle of Tolerance -- i.e., a tolerant system -- prevent errors -- provide error recovery (undo, help) -- possibly 'understand' errors and then guide user Check Principles + for Experience principle of Visibility -- can you see the possible controls to use? -- can you see system status? principle of Affordance -- what action does a control suggest? e.g., Toaster e.g., Door handle for dummies principle of Feedback -- do you know that the control was used? Check Eight Golden Rules of Interface Design Check Ten general usability heuristics (Heuristic Evaluation) Check Data Display Guidelines Check Data Entry Guidelines	Ch.5, 9
	Usability metrics         ... for Evaluation (and Design) Let's try it for a layout example... Uses of & requirements for metrics - slides (pdf) Usability metrics from Constantine & Lockwood 1999 (Handout). Essential Efficiency, Task Concordance, Task Visibility, Layout Uniformity, Visual Coherence.	Ch.6, 21
Map	Interaction Techniques: Menus intro Intro to Menus and Forms -- for controls, info provision and data input. Info for selection, reduces memory load, good for inexperienced users, provides structure, relates to task. *Design Issues: intra- and inter-menu organization When Menus are appropriate Textual or graphical. -- EKG machine; ATM Semantic Organization: menus & their grouping must relate to user's task must provide correct expectations (i.e., locus of control) comprehensive & distinctive categories; Mechanisms for movement within and between menus (e.g., up, down, top, other) how??? Various menu types: single, linear, hierarchy, network Will need menu aids for experts. Why??? Consistency in all things! Single Menus what is a single menu??? Remember... -- consistent format -- show default -- show previous selection -- show what is not selectable -- reading direction biases??? Pop-up: in response to pointing device, at cursor. -- advantages??? disadvantages??? role of Fitts law??? Pull-down: typically from menu bar. -- advantages??? disadvantages??? -- can be extended to a menu of menus. Permanent: always available. -- advantages??? disadvantages??? -- where to place it and why?	Ch.11, 16
	Menus (continued) Single Menus (continued) Multiple items: single selection vs. multiple selections. Radio button & Check boxes as metaphor? How to set default (use previous selection?) How to indicate that nothing has been selected? How to show that you are finished? Pie Menu - Relationship to Fitts Law easyGestures + Linear sequence set of items, actions or choices, all to be seen/done. e.g., parameter setting or feature selection task related order and grouping need to be able to reverse and/or undo provide summary at end before confirmation could use "multi-menu" instead (group) Tree structured (hierarchy) Best shape & why??? Problems due to hierarchy??? (slides)	Ch.11
	Menus (continued) Organization of menu items -- semantic, alpha, etc. -- grouping & sequence (slides) Experts and menus -- shortcuts, typeahead, direct access, menu macros. -- In menu aids for experts: Mnemonic, letter shortcuts (e.g., control+P = Print ) Menu Titles & Items Selection & Activation -- textual & graphical Designing Menu Systems Fill-In Forms Fill-In Forms self-explanatory require little memory effective use of screen space allows input of parameters with many values provides visible context changes are visible (e.g., new field) BUT assumes knowledge of valid inputs assumes typing skill assumes knowledge of special keys can be inflexible and system in control When Fill-In Forms are appropriate Designing Fill-In Forms Fairmont Hotels Case Study + Boingo & BA Case Study + General Guidelines include: using standard elements consistency -- internal, external avoid disorganization, crowding, interference avoid spatial tension use good figure/ground contrast group using layout whitespace is important design to a grid	Ch.11, 16
	Command Languages Command languages appropriate for...? (slide) Characteristics -- immediate effect -- user in control! -- brief input -- typing skill -- puts load on user's memory (due to syntax) -- for expert & frequent users (if not???) Language design goals (slide) Supporting user's task provide functionality enough power provided (can do task?) too much power? -- slows learning -- increases chance of error -- more help & manuals req'd -- 80-20 need to do task analysis to determine commands needed transition diagrams used to describe effects of commands Command organization simple -- one per task command+args -- position vs. keyword -- defaults assumed? command+options+args -- difference between options and args? -- extras add complexity -- tax memory -- increase errors -- command language macho! (slide) hierarchical -- MOVE ROBOT FORWARDS -- note "congruent" (insert/delete)	Ch.11
	Commands (continued) Naming -- be specific ("insert", not "add") -- familiar terms & task terms -- congruent terms -- mnemonic (memory aid) -- distinct (print vs. primp) -- good abbreviations What to do with very high frequency commands ? Prompting & completion Abbreviations -- requirements??? -- good methods for production??? Designing Command Languages Command naming experiment Command naming: can we agree? maybe only 20% of the time try using most frequent choice allow customization	--
	Natural Language input vs. output; spoken vs. textual when appropriate??? -- input text vs. output text -- input spoken vs. output spoken what's possible??? -- input text vs. output text -- input spoken vs. output spoken Elbot+ Google speech-recognition+ Siri+ strengths & weaknesses??? -- natural -- training needed??? -- is subset natural??? -- good for commands and queries -- ambiguous -- typing leads to errors -- noise can lead to errors -- can train user with (NL) feedback -- users make incorrect assumptions about system abilities Direct manipulation WIMP interfaces (Windows, Icons, Menus and Pointing device) -- WIMP may not be Direct Manipulation Direct Manipulation visible actions and objects manipulate directly emphasize task, minimize computer concepts minimize syntax (and typing) learning enhanced by action natural cursor control (for task) -- hands, eyes, fingers -- eyetracking + -- 3D gesture + Metaphors (to suggest a similarity with a real thing/process) BUT use metaphors with care + Slurp + Affordances (principle) Norman's article + Reinforce conceptual model (affecting users mental model) Extreme Direct Manipulation: BumpTop desktop + Tangibles: Toy blocks that "think" + why it works user in the task: tool vanishes representation of reality direct involvement physical/graphical representations can enhance p-s. visual representations encourage retention its problems icons/diagrams may be confusing abstracted reality isn't real (behavior) e.g., users may infer incorrect properties -- what's on real desk top? -- what if I tilt the desk? -- trash can has weight? -- if trash can full? text has higher density of information typing often faster best for few objects & actions bad match for looping/searching	Ch.10
	Direct Manip.: Impact of video games sophisticated sound & graphics challenging tasks (more "interesting") significant user base abstractions of reality (expectations) use of natural controls (special devices) immediate feedback (high involvement) learning by doing games vs. applications! Icon Design what is an icon ??? cows planes birds icon examples Icon design lexical syntactic semantic pragmatic dynamics impact on "gulf of execution" and "gulf of evaluation". icon design schemes resemblance symbolic exemplar (typical example) analogy (e.g., cut = scissors) more icon examples icon guidelines international aspects Summary: Designing Direct Manipulation Interfaces Dialog styles (reminder)	Ch.16
Map	Device evaluation Interaction Devices Key question -- how do we know that they are any good? What are the interaction devices ??? for "normal" computer applications? for games? for VR? + for life? (ubiquitous) How to Evaluate what are the evaluation factors for comparison ???? -- in addition to basic metrics Role of Fitts' Law ??? Pointing device tasks -- how does each device do each task ???? Select Position Orient Path Quantify Text manipulation Direct vs. Indirect direct touch screen, pen/stylus (on screen only) strengths & weaknesses ???? -- e.g., touch screen -- e.g., beyond the touch screen + indirect mouse, trackball, joystick, graphics tablet (off screen) strengths & weaknesses ???? -- e.g., mouse What type is keyboard? (strengths & weaknesses?) -- arrow keys	Ch.12
	Keyboards Consider a device we know a lot about ...what can we learn about device design issues from it? What do we know: left handed typists??? Keyboard history Why would you need to design a keyboard ??? Keyboard design types (chord, split, ...) how does user get feedback from keyboard??? key & keyboard characteristics -- e.g., dimensions & other parameters keyboard layouts -- e.g., QWERTY, Dvorak, Alpha, ... -- Typing effort -- QWERTY -- Dvorak -- Colemak Variable layouts Keyboard variations+ Speeds Task Analysis: frequencies -- Letter, pair and word frequencies numeric keys bring back the rotary phone? Bell Labs 1960 study Fn keys types cursor keys grouping/labelling	--
Map	Error messages Errors due to lack of knowledge (what to do??) incorrect understanding (what to do??) inadvertent slips (what to do??) Fatal error, buddy. That input really sucked! + Errors lead to feelings of ....?? What type of users makes errors?? In what situations?? When do you need to get the user's attention?? how?? how often?? Prevent Errors User's make lots of mistakes! (30%?) Design strategies Fail Safe -- safe shut down at system failure Monitoring -- provide early signs of error/failure Protection -- protect user from consequences of error/failure Warning -- about impending problems Interlocks -- make sure that conditions are right for action Things to do Constructive error msgs Undo, Cancel Avoid "modes" Consistency Provide feedback -- gently reinforce correct behavior? Require confirmation. OK? Reduce typing Reduce ambiguity Reduce memory load *** Avoid distractions. Help with "standard forms" and conventions (e.g., date, SS#, US state) Reinforce Conceptual Model Make computers/people do what each does better! Error messages guidelines for error msgs clear, precise, soothing, helpful -- i.e., what does the user need? specificity (what, where) (mark error) guidance (how to fix) -- might need to describe the "rule" being violated -- i.e., train the user tone (be positive, not alarmist) good language (based on TA&UA) user centered: user in control -- e.g., avoid imperatives -- e.g., variable verbosity format (not all caps)(indicate error msg type) placement (standard place)(near error) when to present (disturbing?)(after closure??) (N.B. The memory release sense of "closure") quality control (guidelines/standards)(usability tests) avoid anthropomorphism (system isn't a person) analyse error frequencies & distribution! -- then make adjustments to interface	Ch.3, 9, 13, 16
	Color Color intro: color examples and confusions (slides) uses for color -- emphasis, warning, grouping, distinctions, attractiveness color wheels color schemes color deficiency / blindness Color pairs -- Red and Blue -- Red and Red? -- Red and Green -- Color in context Grouping methods -- line, white space, color, shape. Contrast for readability use black with light colors, and white with dark colors. color/color contrasts can be increased by adding white to make a tint, or adding black to make a shade. color meanings e.g., Red for {heat, anger, power, danger, emotion, importance} or other meanings (Red) use of color -- Guidelines Asian Color Symbolism (cultural impact) Red: Happiness, marriage, prosperity Pink: Marriage Yellow: Against evil, for the dead, geomantic blessings Green: Eternity, family, harmony, health, peace, posterity Blue: Self-cultivation, wealth Purple: Wealth White: Children, marriage, mourning, peace, purity, ... Gold: Strength, wealth Gray: Helpful people, travel Black: Career, evil influences, knowledge, mourning, penance, ...	Ch.3, 9, 13, 16

... plus a healthy dose of Dilbert.

http://www.cs.wpi.edu/~dcb/courses/CS3041/the-story.html