design of interactive systems

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OVERHEADS I: DESIGN OF INTERACTIVE SYSTEMS

•by MURRAY TUROFF•DEPARTMENT OF COMPUTER AND INFORMATION SCIENCE•NEW JERSEY INSTITUTE OF TECHNOLOGY•NEWARK NJ, 07102•TEL: 201 596 3399•© Copyright 1991 Murray Turoff

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DESIGN METHODS

•COMPARISON / DIFFERENTIATING•DESIGNING / REQUIREMENTS•TASK UNDERSTANDING / MACRO•COGNITIVE UNDERSTANDING / MICRO•GROUP UNDERSTANDING / MICRO & MACRO

•ENHANCEMENTS / EVOLUTION•VISIONING / NORMATIVE•SOCIAL ENGINEERING•GOAL SETTING

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ATMOSPHERE

•HUMAN COMPUTER

•SLOW RAPID•SLOPPY RIGOROUS•FORGETFUL PRECISE•BRILLIANT STUPID

•HOW TO DESIGN A COMMUNICATION BETWEEN THE TWO?

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WHY INTERACTIVE

•ITERATIVE PROBLEM SOLVING•UNPREDICTABLE SEQUENCES•TOOL FLEXIBILITY•IMPOSSIBLE MANUALLY•COLLABORATION•ENHANCEMENT (SAVE TIME, EFFORT)•SPEED, QUANTITY, MEMORY

•ENJOYMENT•SUBLIMATING AND BEING BUSY

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DESIGN ATMOSPHERE

•PERSONAL WORKSTATIONS•MEGABYTES OF CORE•OPTICAL DISKS•MANY MIPS•BROAD BAND COMMUNICATIONS

•USERS•HIGH COGNITIVE VARIABILITY•MANAGERIAL•PROBLEM SOLVERS•SCIENTIFIC AND ENGINEERING•CREATIVE

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VIEWS OF THE WORLD

•REAL WORLD•OUTCOMES:VALIDATION

•REQUIREMENTS MODEL•SYSTEMS ANALYSIS: EVALUATION

•IMPLEMENTATION MODEL•SYSTEM DESIGN: TESTING

•INTERFACE MODEL•METAPHOR: SYSTEM OPACITY

•MENTAL MODEL•EXPERIENCE: FUNCTIONAL OPACITY

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USER TYPES & MODES

•NOVICE, CASUAL, INTERMEDIARIES•EXPERIENCED•ROUTINE•FREQUENT•OPERATORS•PROBLEM SOLVERS•POWER•RESULTS:•DIFFERENT ROLES IN ONE SYSTEM•MULTIPLE INTERFACE METHODS

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DIMENSIONS OF INTERFACE DESIGN

•© copyright 1991 Murray Turoff

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•CRITERIA FOR FACTOR DIMENSIONS•CAN IT BE PERCEIVED•CAN IT BE MEASURED•REPRODUCIBLE•RELIABLE

•ORTHOGONAL•CAN IT GUIDE DESIGN•RELATE TO INTERFACE METHODS•CAN IT EVALUATE DESIGN•CAN IT SENSITIZE

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•FOUNDATION FACTORS•UNDERSTANDING & EASE OF LEARNING•SENSE OF CONTROL•EFFECTIVENESS•PSYCHOLOGICAL & SOCIOLOGICAL•ADMINISTRATIVE

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•FOUNDATION FACTORS•TIMELINESS•RESPONSIVENESS•RELIABILITY•ACCESSIBILITY / CONVINCE•EFFICIENCY / LEAST EFFORT•SECURITY•ACCURACY•PROTECTION / BULLET-PROOFING

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•UNDERSTANDING / EASE OF LEARNING•GUIDANCE•INFORMATIVENESS•CONCISENESS / BREVITY•CLARITY / SIMPLICITY•COMPREHENSION•SEGMENTATION / DECOMPOSITION•CONSISTENCY•RETENTION•SPECIFICITY•FAMILIARITY

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•SENSE OF CONTROL I•LEVERAGE / MODIFIABILITY•MANIPULABILITY•CLOSURE / CONFIRMATION / NOTIFICATION•FEEDBACK•SENSE OF CAUSALITY•MULTI-TASKING•PROCESS CONTROL / ESCAPE / INTERRUPT

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•SENSE OF CONTROL II•FORGIVENESS•TRANSPARENCY•FLEXIBILITY / COGNITIVE ADOPTION•PREDICTABILITY / REGULARITY•CONTEXTUAL VISIBILITY•TRACKING•BACKTRACKING / AUDITING•FORECASTING / ANTICIPATING•BACKUP / UNDO

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•EFFECTIVENESS I•TASK FUNCTIONALITY•GENERALITY•MATCHING•COMPLETENESS•ROBUSTNESS•ABSTRACTION•ADAPTABILITY

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•EFFECTIVENESS II•INTEGRATION / CONNECTIVITY•RESILIENCY / ROBUSTNESS / RICHNESS•RELEVANCE•PRECISION

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•PSYCHOLOGICAL & SOCIOLOGICAL I•ETHICAL / HONESTY•AESTHETIC / PLEASING / ARTFUL•INTERESTING / CHALLENGING / FUN•SELF IMAGE ENHANCEMENT•EXPECTATIONS / MOTIVATION•PEER RELATIONS / STATUS•SENSE OF COMMUNITY•HUMANIZATION / POLITE

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•PSYCHOLOGICAL & SOCIOLOGICAL II•SATISFACTION•SYSTEM•GROUP•TASK

•MOTIVATION•EXPECTATIONS•PERCEIVED UTILITY•FEELING OF PARTICIPATION

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•ADMINISTRATIVE•TRAINING / DOCUMENTATION•MAINTENANCE•JOB ENHANCEMENT•HUMAN HELP•ORGANIZATION RELATIONSHIPS•SYSTEM EVOLUTION / MODIFIABILITY•EVALUATION / FEEDBACK•CHARGING POLICIES•CONFIDENCE

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•CONFLICTS AND TRADEOFFS: EXAMPLES

•COMPREHENSION SEGMENTATION•CONSISTENCY EFFICIENCY•CONSISTENCY COGNITIVE ADOPTION•CONCISENESS INFORMATIVE•CONCISENESS CLOSURE•RESILIENCY EASE OF LEARNING•TASK GENERALITY TASK MATCHING•SPECIFICITY FAMILIARITY•LEVERAGE MANIPULABILITY

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BASIC PROBLEM

•PROPER LEVEL OF TOOLS•TOO PRIMITIVE:•DIFFICULT TO WORK WITH

•TOO MACRO:•INFLEXIBLE

•GULF OF EXECUTION•GOALS, INTENTIONS, TO ACTIONS

•GULF OF EVALUATION•DISPLAY, INTERPRETATION, TO EVALUATION

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CONTROL SYSTEM VIEW

•INPUT - CONTROL•OUTPUT - RESULT•SYSTEM - BLACK BOX•OBJECTIVE - COMPARATOR•LAW OF REQUISITE VARIETY

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EVALUATION OF INTERFACES


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EVALUATION OF INTERFACES

•INDUSTRIAL ENGINEERING - HUMAN FACTORS•PSYCHOLOGICAL AND SOCIOLOGICAL•PROTOCOL ANALYSIS•CONTROLLED EXPERIMENTS•FIELD TRIALS•INTERVIEWS•SURVEYS•LONGITUDINAL STUDIES

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EVALUATION OF INTERFACES I

•MANAGEMENT SCIENCES - PERCEPTIONS•SYSTEM MONITORING•USER SATISFACTION•COST - BENEFITS / PRODUCTIVITY•EFFICIENCY•QUALITY•OPPORTUNITIES

•INDUSTRIAL ENGINEERING•HUMAN FACTORS

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EVALUATION OF INTERFACES II

•PSYCHOLOGICAL•COGNITIVE PROCESSES•HUMAN PROBLEM SOLVING

•SOCIOLOGICAL•GROUP PROCESSES•ENVIRONMENTAL INTERACTION

•EVALUATION OF INTERFACES

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EVALUATION OF INTERFACES III

•ANTHROPOLOGICAL•METAPHORS•PARTICIPANT OBSERVATION

•ARCHAEOLOGICAL•ARTIFACTS

•PHILOSOPHICAL•VIRTUAL REALITY

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APPROACHES TO UNDERSTANDING

•EXPERIMENTAL•FEATURES RELATIONSHIPS•COGNITIVE PSYCHOLOGY FACTORS•MODELS OF TOTAL SYSTEMS•HUMAN•TASKS•COMPUTERS

•FIELD TRIALS AND PROTOTYPING•ARTIFACTS AND METAPHORS•SOCIAL ENGINEERING

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EXPERIMENTS

•FIXED MESSAGE FORMAT VS. USER DESIGNED•LESS NOTE TAKING•GREATER COMPREHENSION

•DUAL MODE EDITOR•AFTER 16-20 HOURS USERS SWITCHED TO COMMANDS•USED HELP MORE IN COMMAND MODE•MORE ERRORS

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MENU CRITERIA

•TIME TO CREATE MENU < CHOICE TIME•MENU EXTENSIBLE BY USER•THEN BETTER THAN COMMANDS EVEN FOR EXPERTS

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SPECIFIC DESIGN FAULTS I

•POOR INTERACTIVE DIALOGUE•LONGER TO DO THAN MANUALLY•NO TOLERANCE FOR HUMAN ERRORS•NO FLEXIBLE PARSING (RIGIDITY)•WRONG FUNCTIONALITY•START-STOP HASSLE•POOR DOCUMENTATION AND HELP•INCONSISTENT METAPHORS

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SPECIFIC DESIGN FAULTS II

•MOST COMMON PROBLEM: FLEXIBILITY•APPLICABILITY TO BROAD RANGE OF TASKS•MULTIPLE APPROACHES TO A GIVEN TASK•MULTIPLE WAYS OF INVOKING•ADAPT TO DIFFERENT•USER STYLES•USER TYPES

•GREATER FLEXIBILITY IMPLIES MORE COMPLEX SYSTEM

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PSYCHOLOGICAL IMPACTS

•FISHBOWL•BULLY•PEEPHOLE•CONCRETE•CLUTTER•PEOPLE ANGST•COMPUTER ANGST•RORSCHACH BLOT

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PHASES OF USER EVOLUTION

•UNCERTAINTY•INSIGHT•INCORPORATION•SATURATION

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PSYCHOLOGICAL ROLES

•EVALUATOR MAGICIAN•HELPER ENTERTAINER•COMPANION CHALLENGER•FOE MENTOR•ACCOMPLICE PRODUCER•OVERSEER DICTATOR•PRIEST SERVANT•PICKY PARENT GOD

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DESIGN INTRODUCTION


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CONTROL FUNCTION EXAMPLES

•GO BACK (HOW FAR)•GO FORWARD (HOW FAR)•GO ELSEWHERE (HOW FAR)•PRINT/FILE (HOW MUCH)•OBJECT, SCREEN, HALF SCREEN, PAGE, LIST

•INTERACTION STATE, TASK, FUNCTION, PROCESS, TRANSFER, UP/DOWN LOAD•CONFIRM, QUIT, HELP, UNDO, ESCAPE, FINISH, INTERRUPT, CONTINUE, TRANSFER, QUIT, SAVE, EXECUTE, OPEN, CLOSE, TRANSFER, COPY, MOVE

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INTERACTION METHODS

•MENUS, COMMANDS•LISTS, FORMS, DIALOGUE•WINDOWS, ICONS, GUI•DIRECT MANIPULATION•MIMICKING / RECORDING•ANIMATION AND MODELS•LANGUAGES•SCRIPTING•VIRTUAL REALITIES•AI AND EXPERT SYSTEMS

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DESIGN COMPONENTS I

•GOALS AND OBJECTIVES•TASKS•SYSTEM METAPHOR•SYSTEM ARTIFACTS

•OBJECTS / SUB-OBJECTS•OBJECT PARTS•SHORTEST, ABSTRACT, CONTENT

•FUNCTIONS ON OBJECTS•GENERIC AND EXPLICIT•STRATEGIC CHOICE SETS•REACTIVE CHOICE SETS•CONTROLS

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DESIGN COMPONENTS II

•MODIFIERS AND STATUS STATES•SUBSETS, TRACKING

•LATERAL LINKAGES•SHARED PROCESSES•LIST PROCESSING•SEARCHING

•FORMATS•SCREEN LAYOUTS•WORKSPACE, STATUS AREAS•CONTROL AREA, MESSAGE AREA

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DESIGN COMPONENTS III

•USER INTERACTION STATES•INTERACTION PROCESSES•USER OBJECT LISTS•USER TASKS•ALTERNATIVE SETS•PROCESSES AND CLOSURE•ERROR CONDITIONS•SYSTEM MESSAGES

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MODEL RELATIONSHIPS

•MENTAL MODEL TO REAL WORLD: EXPERIENCE•REQUIREMENTS MODEL TO IMPLEMENTATION MODEL: TESTING•REAL WORLD TO IMPLEMENTATION MODEL: VALIDATION•MENTAL MODEL TO IMPLEMENTATION MODEL: EVALUATION•MENTAL MODEL TO INTERFACE MODEL: LEARNING AND TRAINING

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MODELS

•COGNITIVE DISSONANCE:•MENTAL MODEL TO INTERFACE MODEL:•FUNCTIONAL OPACITY

•IMPLEMENTATION MODEL TO INTERFACE MODEL:•SYSTEM OPACITY

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INFORMATION DOMAINS OF USERS I

•COMMON IS SUPPORT LEVELS•SINGLE FUNCTION TASKS:•SIMPLE INQUIRY / CALCULATIONS / MESSAGING

•STRUCTURING:•ORGANIZING / FILTERING / SUMMARIZING

•STATUS BRIEFING / REPORT GENERATION•TRACKING / MONITORING

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INFORMATION DOMAINS OF USERS II

•CURRENT INDIVIDUAL CHALLENGES•EXCEPTION REPORTING•CREATION TASKS•MODELING / STRUCTURING•DIAGNOSIS•DISCOVERY•HYPOTHESIS TESTING AND ANALYSIS

•CURRENT GROUP CHALLENGES•PLANNING AND DECISION ANALYSIS•DECISION IMPLEMENTATION•COMMAND AND CONTROL

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FOLKLORE OF INTERACTIVE SYSTEMS


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FOLKLORE OF INTERACTIVE SYSTEMS I

•USERS:•FAILURE TO NOTICE EXPLICIT INSTRUCTIONS•DO THE UNANTICIPATED AND THE FORBIDDEN•FORMULATE OPINION ON LITTLE KNOWLEDGE•MISINTERPRET MEANINGS•WILL NOT ASK FOR HELP•WILL NOT REPORT BUGS

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FOLKLORE OF INTERACTIVE SYSTEMS II

•USERS:•WILL NOT APPRECIATE IMPLEMENTATION EFFORT•ONLY APPRECIATE UTILITY TO THEM•WILL FALL INTO HABITS•WILL NOT READ MANUALS•NOT UNDERSTAND DOCUMENTATION

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FOLKLORE OF INTERACTIVE SYSTEMS III

•DESIGNERS:•EXPECT USERS TO LEARN WHOLE SYSTEM•TO UNDERSTAND WHOLE SYSTEM•WILL RE-INVENT THE WHEEL•TREAT ALL USERS THE SAME•WILL NOT TAKE CRITICISM WELL•WILL NOT EXPLAIN THEIR DESIGN•CANNOT TEACH USERS

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FOLKLORE OF INTERACTIVE SYSTEMS IV

•GENERAL I:•BEST WAY OF USING COMPUTER NOT EVIDENT TO USER•WRONG TO AUTOMATE, BUT EASY TO SELL•DESCRIPTIVE DESIGNS CAN BE PRESCRIPTIVE•USER BEHAVIOUR WILL CHANGE AND EVOLVE•DESIGNER HAS LINE OF CREDIT

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FOLKLORE OF INTERACTIVE SYSTEMS V

•GENERAL II:•DESIGNER KNOWLEDGE OF TASK CRITICAL•TWO OR MORE SHOULD DESIGN•ROLE FOR OMBUDSMAN•MULTIPLE DESIGN ITERATIONS DESIRABLE•ALLOW USER TO "CHUNK" PROBLEMS•USER FRIENDLY - EXPERIENCED HOSTILE

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FOLKLORE OF INTERACTIVE SYSTEMS VI

•GENERAL III:•VALUE WILL OVERCOME POOR INTERFACE•BEST SYSTEM IS THE FIRST LEARNED•EFFICIENT COMPUTER DATA STRUCTURE MAY BE INEFFICIENT FOR THE USER

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FOLKLORE OF INTERACTIVE SYSTEMS VII

•GENERAL IV:•USERS LEARN BEST BY TRAIL AND ERROR•EFFICIENT USE OF MACHINE MAY EQUAL INEFFICIENT USE OF PEOPLE•EXPERIMENT LEADS THEORY•DESIGNERS SHOULD KNOW APPLICATION AREA•REMEMBER THE MAGIC NUMBER 7 +- 2•A SYSTEM EVOLVES OR DIES

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FOLKLORE OF INTERACTIVE SYSTEMS VIII

•GENERAL V:•EVALUATING THE USER NOT A SYSTEM TASK•USERS WANT TO IGNORE SYSTEM•INVOLVE THE USER IN THE DESIGN PROCESS•ERROR DETECTION AS SOON AS POSSIBLE•USERS SHOULD HAVE CONTROL

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USER ROLES AND TYPES

•NOVICE, CASUAL, ROUTINE•INTERMEDIARY•FREQUENT•OPERATOR•EXPERIENCED•PROBLEM SOLVER•POWER•RESULTS:•DIFFERENT ROLES IN ONE SYSTEM•MULTIPLE INTERFACE METHODS

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USER RESPONSE TO INADEQUATE SYSTEM

•DIS-USE: TURN TO OTHER SOURCES•MIS-USE: USING INAPPROPRIATE WAYS•PARTIAL USE: USE OF WRONG SUBSET•DISTANT USE: USE OF INTERMEDIARY•MODIFICATION OF TASK: CHANGE TASK TO FIT SYSTEM•COMPENSATORY ACTIVITY: USER HAS TO DO MORE•DIRECT PROGRAMMING: USER MODIFIES SYSTEM•NON-USE: AVOIDING THE SYSTEM

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PROTOCOL ANALYSIS


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PROTOCOL ANALYSIS I

•OBJECTIVE: TO DISCOVER THE PROCESS A PERSON GOES THROUGH IN SOLVING A PROBLEM•USES: LEARNING COGNITIVE PROCESSES, DEVELOPING EXPERT SYSTEM MATERIAL, EVALUATING INTERFACES

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PROTOCOL ANALYSIS II

•ASSUMPTION: COGNITIVE PROCESSES THAT GENERATE VERBALIZATION ARE A SUBSET OF THOSE THAT GENERATE BEHAVIOUR•EXAMPLE: "LISA LEARNING," BY CARROLL AND MAZUR, IEEE COMPUTER, NOVEMBER 1986.

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PROTOCOL ANALYSIS III

•INVERSE RELATIONSHIP BETWEEN THE AMOUNT OF TRUST AND HOW MUCH NEEDS TO BE REPORTED VERBALLY.•1. DO YOU KNOW THE CAPITAL OF SWEDEN?•2. WHICH OF THE THREE: OSLO, STOCKHOLM, OR COPENHAGEN IS THE CAPITAL?•3. NAME THE CAPITAL OF SWEDEN.

•RETROSPECT TO 1: TELL WHAT YOU WERE THINKING

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PROTOCOL ANALYSIS IV

•TALK ALOUD, THINK ALOUD MODE: WHILE INFORMATION IS ATTENDED.•CONCURRENT PROBING MODE: WHILE IN SHORT-TERM MEMORY.•RETROSPECTIVE PROBING MODE: AFTER COMPLETION OF TASK

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PROTOCOL ANALYSIS V CONDITIONS

•SUBJECT ASKED TO VERBALIZE WHAT THEY ARE THINKING•SUBJECT IS NOT BEING EVALUATED•OBSERVER MUST NOT PARTICIPATE IN PROCESS OR AID SUBJECT•SUBJECT PROVIDING KNOWLEDGE OF HOW THEY SOLVE A PROBLEM OR HOW THEY LEARN A SYSTEM

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PROTOCOL ANALYSIS VICODING

•NEED A CODING SCHEME FOR VERBALIZATIONS•EXAMPLE I:•INTENTIONS: GOALS, SHALL, WILL, MUST, HAVE TO•COGNITIONS: CURRENT ATTENTION SITUATION•PLANNING: IF X THAN Y•EVALUATION: YES, NO, DAMIT, FINE

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PROTOCOL ANALYSIS VIICODING

•EXAMPLE II:•SURVEYING GIVEN INFORMATION•GENERATING NEW INFORMATION•DEVELOPING A HYPOTHESIS•UNSUCCESSFUL SOLUTIONS•CHANGING CONDITIONS OF THE PROBLEM•SELF REFERENCE OR CRITICISM•SILENCE

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PROTOCOL ANALYSIS VIII

•EXPERTS ON A PROBLEM VERBALIZE A LOT MORE THAN NON EXPERTS (DOUBLE).•VERBALIZATION OCCURS ONLY 30% TO 50% OF THE TIME•PEOPLE CANNOT VERBALIZE WHEN:•READING TEXT•DOING INTENSE COGNITIVE ACTIVITY•MAKING CHOICES

•PEOPLE HAVE TO SLOW DOWN TO VERBALIZE

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PROTOCOL ANALYSIS IX

•HOW TO INCREASE VERBALIZATION•1. HOLD BACK STIMULUS OR ENCOURAGE SLOWNESS•2. SEGMENT STIMULUS•3. INTERRUPT WITH PRE-ARRANGED SIGNAL OR SET POINT

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PROTOCOL ANALYSIS X OBJECTIVES

•OBJECTIVES FOR INTERACTIVE SYSTEMS:•DETERMINE THEIR UNDERSTANDINGS OF TERMS IN THE INTERFACE•UNDERSTAND THE CAUSE OF ERRORS OR MISINTERPRETATIONS•DETERMINING MISSING FUNCTIONALITY OR USER REQUIREMENTS•DETERMINING THE UTILITY OF THE METAPHOR FOR LEARNING•DETERMINING THE UTILITY OF HELP AND GUIDANCE

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PROTOCOL ANALYSIS XIAPPROACH 1

•ASK THE USER TO DESCRIBE WHAT HE OR SHE IS DOING OUTLOUD•TO GO THROUGH THE TERMS ON THE SCREEN AND EXPLAIN WHAT THEY THINK THEY MEAN•TO TRY TO FORECAST WHAT A COMMAND CHOICE WILL DO•CAN RECORD, TAPE, AND/OR MAKE NOTES

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PROTOCOL ANALYSIS XIIAPPROACH 2

•EXPLAIN IT IS SYSTEM BEING EVALUATED, NOT USER•THERE TO OBSERVE ONLY, CANNOT HELP USER•ONLY ASK USER TO VERBALIZE IF IT IS UNCLEAR AS TO WHAT THEY ARE DOING

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PROTOCOL ANALYSIS XIIIAPPROACH 3

•ASK TO EXPLAIN:•1. WHAT THEY ARE TRYING TO DO•2. WHAT CONFUSION OR CONCERNS THEY HAVE•3. WHAT THEY EXPECT TO HAPPEN NEXT•4. WHAT THEY DON'T KNOW THE MEANING OF

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PROTOCOL ANALYSIS XIV APPROACH 4

•GIVE HELP ONLY IF USER IS AT A DEAD END•USERS DO NOT ALWAYS KNOW WHY THEY DO THINGS•SAVE RETROSPECTIVE QUESTIONS FOR END

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PROTOCOL ANALYSIS XVADVANTAGES

•A LOT LESS EFFORT THAN OTHER APPROACHES•CAN BE DONE ON PROTOTYPE OR MOCKUP•LEARNING HOW USER APPROACHES TASK•CAN LEARN ATTITUDE•RAPID FEEDBACK FROM SMALL SAMPLES

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PROTOCOL ANALYSIS XVIREQUIREMENTS

•REQUIREMENTS:•SUBJECTS MUST BE REPRESENTATIVE•INSTRUCTIONS SIMPLE•YOU MUST BE OBSERVER ONLY

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PROTOCOL ANALYSIS XVIIQUESTIONS

•CAN ASK:•WHAT ARE YOU THINKING?•WHAT DOES THAT TERM MEAN?

•SHOULD NOT ASK:•WHY DID YOU DO THAT!•WHAT DOES A MESSAGE DO?

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PROTOCOL ANALYSIS XVIIIHOW TO 1

•A ONE PAGE EXPLANATION TO THE SUBJECT•A SET OF WRITTEN TASKS IN USER TERMS•SUBJECT SHOULD SPEND ABOUT ONE HOUR•A CATEGORISATION SCHEME FOR RECORDING•TAPE RECORD THEIR VERBALIZATIONS

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PROTOCOL ANALYSIS XIXHOW TO 2

•RETROSPECTIVE QUESTIONNAIRE FOR END•RETENTION OF MAJOR CONCEPTS•PERCEIVED UTILITY OF FEATURES

•DO NOT TRY TO TEST EVERYTHING•AT LEAST THREE SUBJECTS ON SAME TASKS•BE SPECIFIC ABOUT USER EXPLAINING CHOICE THEY ARE ABOUT TO MAKE

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GUIDELINES


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MODELS I

•COGNITIVE MODEL•DESCRIPTION OF MENTAL PROCESS BY WHICH HUMAN PERFORMS A TASK

•USER CONCEPTUAL/MENTAL MODEL•DESCRIPTION OF THE MODEL OF THE SYSTEM THAT THE USER UNDERSTANDS

•SYSTEM METAPHOR•DESIGNERS MODEL OF THE SYSTEM INTENDED TO BE THE ONE THE USER UNDERSTANDS

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MODELS II

•IMPLEMENTATION MODEL•MODEL USED TO DESCRIBE THE INTERNAL SYSTEM

•REQUIREMENTS MODEL•MODEL DEVELOPED THROUGH SYSTEMS ANALYSIS PROCESS

•REAL WORLD MODEL•WHAT OCCURS IN THE PHYSICAL WORLD

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GUIDELINES I

•HIGHLIGHTING•COLOR, SOUND, REVERSE VIDEO, FLASHING, SIZE, FONTS, BOXING, WINDOWING•PURPOSE: ATTENTION GETTING AND FEEDBACK

•SCREEN LAYOUT•STATUS, WORK, CONTROL, ERROR, HELP

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GUIDELINES II

•TELL USER WHAT HE/SHE IS WORKING ON•HIGHLIGHT WHAT USER HAS SELECTED•PUT DATA IN SOME ORDER•LONG STRINGS/NUMBERS BROKEN UP INTO MEANINGFUL CHUNKS•106677471812 1066-742-1812

•SCREEN DENSITY 25% TO 50%, 30% USUALLY IDEAL

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GUIDELINES III

•ORDER/GROUP MATERIAL: SEQUENTIAL, CLASSIFIED, HIERARCHICAL•MENU CHOICES: 5 TO 9 (7+-2)•GROUP MENU ITEMS:•CHANGE / NO CHANGE•TWO DIMENSIONAL ( 5 X 5 = 25 )

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GUIDELINES IV

•MENU TYPES•STRATEGIC MENUS / CONTROL PANELS•MENU TREES / OUTLINES•POPUP/PULLDOWN MENUS•LISTS (MULTIPLE CHOICES)•OBJECT MENUS (ICONS)•ACTION MENUS•MODIFIER MENUS

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GUIDELINES V

•CHOICE SELECTION•CURSOR KEYS / MOUSE•SELECTION BAR•NUMBERS•LETTERS•ABBREVIATION

•IMPORTANT FACTORS•FREQUENCY OF USE•GROUPINGS OF COMMANDS•HABIT & ERROR AVOIDANCE•CONTROLS

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GUIDELINES VI

•SEPARATE PARAGRAPHS BY BLANK LINES•USER STANDARD REPRESENTATIONS: HH:MM:SS•USE COMPLETE WORDS•AVOID HYPHENATION•USE VERTICALLY ALIGNED LISTS•USE OUTLINES AND BULLETS•MOST SIGNIFICANT WORDS FIRST•MINIMIZE PUNCTUATION: CPU

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GUIDELINES VII

•LABELING•LABEL OR IDENTIFICATION FOR AN OBJECT•DESCRIPTIVE TITLE, PHRASE•SPEED SCAN OF SHORT VERSION OF OBJECT•FULL STATUS DESCRIPTION OF AN OBJECT•APPLIES TO CONTENT OBJECTS, MENUS, SCREENS, STATES

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GUIDELINES VIII

•USER SHOULD BE ABLE TO CONTROL AMOUNT OF INFORMATION•ALL MEANINGFUL ALTERNATIVES IN ONE SCREEN•CONSISTENCY IN USE OF TERMS•SPECIFICITY OF TERMS DESIRABLE•FAMILIARITY OF TERMS DESIRABLE

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GUIDELINES IXX

•ALLOW SYNONYMS WHERE POSSIBLE•ALWAYS CONFIRM CRITICAL ACTIONS (E.G. DELETE)•MINIMIZE NUMBER OF MODES OF INTERACTION (E.G. EDIT MODE)•DISPLAY ACTION TAKING PLACE (E.G. STATUS)•MINIMIZE SUPERFLUOUS TASKS (E.G. LOGON)

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GUIDELINES XX

•PROMPTS AS SOON AS POSSIBLE AFTER ERRORS•USER GIVEN IMMEDIATE CHANCE TO CORRECT•IDENTIFY ERRORS SPECIFICALLY•PROVIDE RECOVERY INFORMATION•+UNDO OR +OOPS•SHOULD EXPLAIN WHY WHEN SOMETHING CAN NOT BE DONE

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GUIDELINES XXI

•ALLOW USER TO STAY IN ONE MODE OF ENTRY AS LONG AS POSSIBLE•ALLOW ENTRY STACKING OR ANSWER AHEADS•USE LOWER AND UPPER CASE

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INDEXING


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INDEXING I

•HIERARCHICAL•SINGLE LOCATION IN TREE•PRECISE DEFINITIONS•E.G. 1. 1.1 1.2 1.1.1•E.G. OUTLINES, MS/DOS FILES•RIGID, DIFFICULT TO ADAPT

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INDEXING II

•NETWORK (LATERAL LINKS)•SINGLE LOCATION IN NETWORK•PRECISE RELATIONSHIPS•E.G. BOOK INDEX, CITATION INDEX•E.G. HYPERTEXT•LACK OF GLOBAL VIEW

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INDEXING III

•SUBJECT HEADINGS•MULTIPLE SUBJECT HEADINGS•FIXED CATEGORIES, NO STRUCTURE•PRECISE DEFINITIONS•E.G. COMPUTERS IN CHEMISTRY AND INTEGRAL EQUATIONS

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INDEXING IV

•KEY WORD AND COORDINATE SYSTEMS•FIXED KEY WORDS•FREE KEY WORDS•MULTIPLE KEYS•COORDINATES FOR PROPERTIES E.G. TALL, MEDIUM, SHORT

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INDEXING V

•SYNTACTIC LANGUAGES 1•TAGGED DESCRIPTORS•QUALIFIED KEYS•E.G. TANK.WEAPON, TANK.PETROLEUM

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INDEXING VI

•SYNTACTIC LANGUAGES 2•FACETED INDEX•SEPARATE DIMENSIONS•E.G., QUANTITY, STYLE, COLOR•E.G., FOR LEATHER, WINE, METAL ALLOYS•E.G., AUTHOR, TITLE, SOURCE•E.G., STEEL, COMPONENT, INDUSTRY

•MIXED INDEXES•UNIVERSAL DECIMAL CLASSIFICATION

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INDEXING VII

•UNIVERSAL DECIMAL CLASSIFICATION•341.67:623.454.8(094.2)

•341.67: DISARMAMENT, LIMITATION AND CONTROL OF WEAPONS OF MASS DESTRUCTION•623.45: AMMUNITION, PYROTECHNIC DEVICES, WEAPONS OF MASS DESTRUCTION•623.454.8: ACTIVE RAYS, ATOMIC NUCLEAR (THERMO) WEAPONS•094.2: HISTORICAL SOURCES (09), INTERNATIONAL TREATIES

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INDEXING VIII

•PHRASES•SHORT PHRASES, TITLES•E.G. KWIC INDEX•E.G. CHAPTER HEADINGS

•NATURAL LANGUAGE•E.G. ABSTRACTS

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INDEXING EFFECTIVENESS IX

RELEVANT NON-RELEVANT•RETRIEVED A B•NOT RETRIEVED C D•PRECISION = A / (A+B)•RECALL = A / (A+C)•SPECIFICITY = D / (B+D)

•SEARCH EFFICIENCY = (RECALL)

(SPECIFICITY)

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INDEXING EFFECTIVENESS X

•TIMELINESS (UPDATING)•ACCURACY•COMPLETENESS (ALL IN DATABASE)•FORM OF DATA (E.G. SUMMARY, RAW DATA)•SUBJECTIVE / OBJECTIVE•ADOPTION•HISTORICAL RELEVANCE

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INDEXING XI

•INDEX TYPE• AMBIGUITY EXPRESSIVE CONCISE•HIERARCHICAL• LOW LOW HIGH•NETWORK•SUBJECTS•FIXED KEYS•FREE KEYS•TAGGED DESCRIPTORS•FACETED INDEXES•PHRASES•NATURAL LANGUAGE• HIGH HIGH LOW

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INDEXING XII

•INDEX TYPE• RETRIEVAL SELECTION ADOPTION• EFFORT EFFORT EFFORT•HIERARCHICAL• LOW HIGH HIGH•NETWORK•SUBJECTS•FIXED KEYS•FREE KEYS LOW•TAGGED DESCRIPTORS•FACETED INDEXES•PHRASES•NATURAL LANGUAGE• HIGH LOW HIGH

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INDEXING XIII

•INDEX TYPE IDEAL USE•HIERARCHICAL•MACRO, WELL STRUCTURED

•NETWORK•MICRO, STRUCTURED RELATIONSHIPS

•SUBJECTS•MACRO, STRUCTURED CONCEPTS

•FIXED KEYS•FREE KEYS•MICRO, UNSTRUCTURED

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INDEXING XIV

•TAGGED DESCRIPTORS•FACETED INDEXES

•MICRO, STRUCTURED FACTORS•PHRASES

•MACRO, SEMI STRUCTURED•NATURAL LANGUAGE

•MACRO, UNSTRUCTURED

112

INDEXING XV

•ZIPF'S LAW•LOG FREQUENCY OF TERMS IN THE ENGLISH LANGUAGE ARE LINEAR WITH LOG OF RANK ORDER•USED TO DETERMINE INDEX TERMS•HIGH FREQUENCY USELESS•LOW FREQUENCY USELESS FOR KEYS LEFT•TERMS DIFFERENT FROM NORMAL ENGLISH

•LEADS TO PRINCIPLE OF LEAST HUMAN EFFORT

114

USER & TASK PROPERTIES


115

USERS AND TASKS

•INDIVIDUAL DIFFERENCES•ABILITIES, SKILLS, BACKGROUNDS COGNITIVE STYLE•DATA DIFFICULT TO USE BY DESIGNERS•IS USED IN SELECTION OF JOBS•OFTEN TIED TO TASK WHICH IS EASIER TO DEAL WITH•VERY USEFUL TO HAVE TASK TAXONOMY•DESIGNERS FAMILIAR WITH TASK DOMAIN USUALLY DO BETTER JOB

116

ERROR ANALYSIS

•ERROR FREQUENCY ANALYSIS CAN BE VERY INDICATIVE OF DESIGN PROBLEMS•SINGLE MOST IMPORTANT MONITORING FUNCTION•SYNTACTIC ERRORS CAN BE USED TO TRIGGER LEARNING AIDS•CONCEPTUAL ERRORS WHERE THE CURRENT CHALLENGE IS

117

USER TASKS

•TRAP OF DESIGNING A SYSTEM WHICH REINFORCES CURRENT USER BEHAVIOUR•MICRO AND MACRO UNDERSTANDING OF TASK•MICRO = COGNITIVE LEVEL•MACRO = FUNCTIONAL LEVEL

•PREDICTING WHAT HAS NOT BEEN POSSIBLE•EXAMPLE: CLASSIFYING COMMUNICATIONS OF A MANAGER

118

USER TASKS

•PAPER SIMULATION•USER OBSERVATION•PARTICIPANT OBSERVATION•PROTOCOL ANALYSIS APPLIED TO TASK•PROTOTYPING ALTERNATIVES•MOCK UPS (DEMO2)

119

TASK MODEL APPROACHES I

•CONTROL SYSTEM MODELS•PHYSIOLOGICAL•SPEED/ERROR ASSESSMENT

•NETWORK MODELS•STATISTICAL•BEHAVIOUR PATTERNS

•DECISION THEORY MODELS•TASK STRATEGIES•E.G., SEARCHES

•INFORMATION PROCESSING MODELS•MEMORY, ATTENTION•RECOGNITION

120

TASK MODEL APPROACHES II

•PROBLEM SOLVING MODELS•MACRO BEHAVIOUR•GOALS, OBJECTIVES

•COGNITIVE MODELS•MICRO BEHAVIOUR•SCANNING, SPECIFICITY, ETC.

•MENTAL (METAPHOR) MODELS•LEARNING•COMPREHENSION

121

PROBLEM OF TASK ALLOCATION:

•WHAT TO GIVE TO THE USER AND WHAT TO GIVE TO THE COMPUTER TO DO•CHOOSING PROBLEM SOLVING AIDS•NOT UNITARY, NOT ONE AID FOR EACH SITUATION•BOTH TASK AND USER EXPERIENCE INVOLVED

122

PROBLEM SOLVING SUBTASKS

•PROBLEM RECOGNITION•PROBLEM DEFINITION•GOAL DEFINITION•STRATEGY SELECTION•ALTERNATIVE GENERATION•ALTERNATIVE EVALUATION

123

ASPECTS OF A TASK

•1. GOALS AND INTENTIONS•2. SPECIFICATION OF ACTIONS•3. MAPPING FROM GOALS TO ACTIONS•4. TRANSLATION: COGNITIVE TO PHYSICAL•5. PHYSICAL STATE OF THE SYSTEM•6. CONTROL MECHANISMS•7. MAPPING PHYSICAL TO CONTROL•8. INTERPRETATION OF SYSTEM STATE•9. EVALUATING OUTCOMES

124

USER ACTIVITIES

•ESTABLISHING GOAL•FORMING INTENTION•SPECIFYING ACTION SEQUENCE•EXECUTING THE ACTION•PERCEIVING SYSTEM STATE•INTERPRETING THE STATE•EVALUATING RELATIONSHIPS

125

BEHAVIOUR DIMENSIONS

•ABSTRACTION NO ABSTRACTION•SEARCH NO SEARCH•DATA DRIVEN CONCEPTUALLY DRIVEN•ABSTRACTION: DEAL WITH STRATEGY•NO ABSTRACTION: GENERATE ALTERNATIVES•SEARCH: NEW STRATEGIES•NO SEARCH: USING ESTABLISHED STRATEGIES•DATA DRIVEN: EVALUATION BY DATA•CONCEPTUALLY DRIVEN: EVALUATION BY CONCEPT

126

METHODS OF PROBLEM SOLVING I

•ALTERNATIVE EVALUATION: SEARCH, NO ABSTRACTION•ALTERNATIVE GENERATION: SEARCH, NO ABSTRACTION, CONCEPTUALLY DRIVEN•BACKTRACKING: NO ABSTRACTIONS, SEARCH•IMPROVING DATA: DATA DRIVEN•CHANGE PROBLEM REPRESENTATION: ABSTRACTION•CONSISTENCY CHECKING: DATA DRIVEN•STRATEGY IMPROVEMENT: ABSTRACTION, CONCEPTUALLY DRIVEN

127

METHODS OF PROBLEM SOLVING II

•DECOMPOSITION AND RECOMBINATION: ABSTRACTION, CONCEPTUALLY DRIVEN•EXTENDED MEMORY: NO ABSTRACTION, SEARCH, NO SEARCH, DATA DRIVEN, CONCEPTUALLY DRIVEN•RAPID TRIAL AND ERROR: NO ABSTRACTION, SEARCH, DATA DRIVEN•STRATEGY CAPTURE (RULE SYSTEMS): DATA DRIVEN

128

DIALOGUE PROPERTIES

•INITIATIVE: COMPUTER OR USER INITIATIVE•FLEXIBILITY: NUMBER OF WAYS A USER CAN ACCOMPLISH A GIVEN TASK•POWER: AMOUNT OF WORK DONE BY THE SYSTEM IN RESPONSE TO A SINGLE USER ACTION•INFORMATION LOAD: DEGREE TO WHICH THE INTERACTION ABSORBS MEMORY AND PROCESSING RESOURCES OF USER

129

GUIDELINES

•INTERFACE BUGS•OUTRIGHT FAILURE•DOING SOMETHING THE WRONG WAY•NOT ALLOWING SOMETHING TO BE DONE•STRUCTURAL: USER CAN DO X Y BUT NOT Y X

130

DESIGN PRINCIPLES

•MAKE EXPLANATIONS BRIEF•ESSENTIAL PART OF DESIGNING USER INTERFACES IS TO EXPLAIN THEM•A STRUCTURE MODEL IS KEY TO UNDERSTANDING•MENDELEEV'S PERIODIC TABLE AND IMPACT ON CHEMISTRY

131

JOSS DESIGN PRINCIPLES I

•EXECUTION STEPS ARE ALWAYS COMPLETED•INTERRUPT CAUSES NO STATE CHANGE•SINGLE MODE•COMMAND CAUSING AN ERROR HAS NO IMPACT•JOSS AND USER PERCEIVE SAME INTERNAL STATE

132

JOSS DESIGN PRINCIPLES II

•JOSS INSISTED ON LETTER PERFECT INPUT/OUTPUT•USER / COMPUTER CONTROL BY LOCKED KEYBOARD -NEVER ANY DOUBT•ANYTHING INPUTTED COULD BE STORED•INCREMENTAL AND BATCH THE SAME

134

USER MENTAL MODELS


135

USER MENTAL MODELS

•USER MODEL IS RARELY VERBALIZED•A USER MODEL IS GENERALLY AS SIMPLE AS POSSIBLE•THE USER MODEL OFTEN CHANGES AS HE OR SHE ACQUIRES MORE KNOWLEDGE ABOUT THE SYSTEM•USER MODELS SHOULD CONFORM TO PSYCHOLOGICAL REQUIREMENTS

136

TASK MODEL OF WRITING IEXPLORE

•I. EXPLORE•GATHER RAW MATERIALS•EXPLORE (BROWSE) MATERIALS•PLAY WITH DIFFERENT CLUSTERS OF IDEAS AND•RELATIONSHIPS•LET IDEAS HAPPEN•MECHANICS•JOT AND POSTING, OUTLINE, DIAGRAMS, FILL IN HOLES, BOTTOM UP, TOP DOWN

•OBJECTIVE: MAP CONCEPTUAL SPACE

137

WRITING IIANALYSES 1

•II. ANALYZE READERS•IDENTIFY READERSHIP•RANK THEM•ESTIMATE WHAT THEY KNOW ABOUT SUBJECT•DETERMINE WHAT YOU HAVE TO TELL THEM•SET GOALS ON HOW MUCH YOU WANT TO CHANGE THEM

138

WRITING IIIANALYSES 2

•CHANGE KNOWLEDGE, CHANGE ATTITUDE•METHODS•ESTIMATE DISTANCE FROM YOU•MATRIX OF CONCEPTS BY READER TYPES

139

WRITING IVFOCUS 1

•III. FOCUS•DECIDE ON THE DOCUMENT YOU WILL WRITE OUT OF ALL POSSIBLE•WHAT IS OVER RIDING POINT•MOST IMPORTANT READERS•CHANGE TO MAKE IN READERS•HOW TO SOUND (IMAGE)

140

WRITING VFOCUS 2

•ORGANIZE TOP-DOWN HIERARCHICAL STRUCTURE•HEADINGS ARE CUES TO READER ON CONCEPTS

•BOTTOM LEVEL:•PARAGRAPH FOR WHAT YOU DO NOT KNOW WELL•PAGE OR MORE FOR MATERIAL YOU KNOW WELL

141

WRITING VIWRITING 1

•IV. WRITE•PRODUCE USABLE DRAFT FOR LATER REVISION•DO NOT REVISE AS YOU GO•ALTERNATIVE WAYS•START TO FINISH•TOP-DOWN: INTRODUCTION AND SUMMARY•RANDOM ORDER•BOTTOM UP: DETAILS FOR EACH SECTION

142

WRITING VIIWRITING 2

•PROBLEMS IN WRITING•WITH WORDING•MARK FOR LATER•3 STRIKES YOUR OUT,•KEEP WRITING

•WITH STRUCTURE•MINOR - KEEP WRITING•MAJOR - RETHINK STRUCTURE

•THINK STRATEGICALLY: TO PERSUADE, TO INFORM, SIGNAL HIERARCHY

143

WRITING VIIIFINAL STAGES

•V. VERIFY AND REVISE•GOAL: TO TURN DRAFT INTO FINISHED PRODUCT•SET PRIORITY AND EFFORT•SYNTACTIC: GRAMMAR, WORD CHOICE, SPELLING•SEMANTIC: OBJECTIVES, STRUCTURE, PARAGRAPHS

•VI. REVIEW•VII. FORMAT•VIII. COLLABORATIVE DOCUMENT

144

WRITING IXSTRUCTURE

•RELATION WRITERS READERS

•NETWORK EXPLORING REMEMBERING•HIERARCHY ORGANIZING COMPREHENDING•SEQUENCE ENCODING DECODING

•DOCUMENT SHOULD SIGNAL STRUCTURE: HEADINGS•PARAGRAPH IS A SINGLE THOUGHT•HYPERTEXT AN APPROACH TO NETWORKS LEVEL

145

WRITING AND READING X

•HIGHLIGHT WHAT THEY WANT: IMPOSE VALUE•ANNOTATE, MARGINAL NOTES•FLIP PAGES BACK AND FORTH•SEEK REFERENCES, INDEX, GLOSSARY, TEXT TO FIGURE, EARLIER ITEMS•MARKING TRIALS•BOOKMARKS FOR INTERRUPTIONS•COPYING NOTES•AGENDA FOR FURTHER WORK

146

MENTAL MODELGUIDELINES 1

•FORM DATA CHUNKS THAT ARE USED THROUGHOUT THE APPLICATION•VERBAL MEDIATION: WITHIN SYSTEM IMPORTANT WORDS SHOULD TAKE ON SPECIALIZED MEANINGS•MODEL PROCESSES IN THE INTERFACE TO THE LEVEL OF DETAIL WHICH THE USER CAN AFFECT, BUT NO MORE

147

MENTAL MODELGUIDELINES 2

•PROCESSES SHOULD BE GROUP TOGETHER TO HIGHER LEVEL: E.G., ALL UPDATING TASKS•LOWER LEVEL PROCESSES SHOULD BE THE SAME WHERE EVER THEY ARE (SEARCH).

148

MENTAL MODELS IINTERACTING OBJECTS &

EVENTS•CASUAL COMMONSENSE•TEXT OBJECT AND MEMBER OBJECT•CHAIN OF EVENTS•SET OF SYSTEM STATES•MORE AMBIGUOUS AND FUZZY•WORK ON OBJECTS•USERS SELECT OBJECT FIRST•AUTOMATIC PROCESSING•PARALLEL PROCESSING•EVENT DRIVEN

149

MENTAL MODELS IIVARIABLES AND RULES

•DETERMINISTIC REASONING•MEASURE BY OBSERVED VARIABLES•MEASURED BY RULES BETWEEN VARIABLES•WORK ON ACTIONS•COMMANDS CHOSEN FIRST•CONSCIOUS PROCESSING•SERIAL PROCESSING

150

MENTAL MODELS III

•USERS WANT TO SUBDIVIDE AND CLASSIFY (ENCODE) SYSTEM•LOW LEVEL OF SYSTEM TO DEAL WITH EVENT DRIVEN PROCESSES (REACTIVE)•HIGHER LEVEL DRIVEN BY GOALS AND MOTIVES (STRATEGIC)

151

MENTAL MODELS IV

•PROBLEM IS POSSIBLE LATERAL PROCESSING BETWEEN BOTTOM LEVEL NODES•BOTTOM LEVEL•DATA DOMAIN FOR ASSOCIATION, RECOGNITION, AND MATCHING•FUNCTIONAL DOMAIN FOR ABDUCTION, DEDUCTION, AND INDUCTION

152

MENTAL MODELS V

•IF SYSTEM STATE IS NOT OBVIOUS USERS WILL ENCODE IT THEIR OWN WAY•PEOPLE DO NOT MIND DEALING WITH COMPLEXITY IF THEY CAN CONTROL IT•BOTH DATA DRIVEN AND HYPOTHESIS DRIVEN MODES SHOULD BE CATERED TO

153

MENTAL MODELS VI

•USERS SHOULD UNDERSTAND ANY INFERENCE PROCESS•STRUCTURE OF GROUPED DATA SHOULD BE EVIDENT•DATA MANIPULATION SHOULD EXHIBIT RESULTS RATHER THAN INFORM IT IS DONE•ONLY ONE EXIT AND ONE ENTRY TO A PROCESS SHOULD BE USED

154

MENTAL MODELS VII

•T(TASK) = T(ACQUIRE) + T(EXECUTE)•ACQUISITION IS MAIN PROBLEM IN REDUCTION OF TIME•USE USERS COGNITIVE MODEL•MATCHING MECHANISMS:•SYNTACTIC (GRAMMAR)•PARAMETRIC (FORM, COLOR, SHAPE)•SEMANTIC (TEXT)•ICONIC (VISUAL PATTERN)

155

MENTAL MODELS VIII

•TASK KNOWING: GOAL AND SUBTASKS TO BE ACCOMPLISHED•INTERFACE KNOWING: MECHANICS OF ACCOMPLISHING TASK•SYSTEM ARCHITECTURE KNOWING: HOW SYSTEM WORKS•DESCRIPTIVE REPRESENTATIONS: WHAT USER CURRENTLY KNOWS•PRESCRIPTIVE REPRESENTATIONS: WHAT USER SHOULD KNOW

156

MENTAL MODELS IXGOMS

•GOMS: GOALS, OPERATORS, METHODS, AND SELECTION RULES•GOALS, SUBGOALS•RULES TO CHOOSE METHODS•SEQUENCE OF OPERATORS TO DO A METHOD

157

MENTAL MODELS XGOMS

•EXAMPLE: SEVERAL WAYS TO FIND FIRST PLACE TO EDIT:•SEARCH, PAGE SCANNING, CURSOR KEYS

•MODELS OF PROCESSING TIME BASED UPON KEYSTROKING VERY ACCURATE•MENTAL MODELS: IF I DO THIS, THIS WILL HAPPEN

158

MENTAL MODELS XIMODEL TYPES 1

•SURROGATES: PERFECTLY MIMICS TARGETS, NO CORRESPONDENCE (SPREADSHEETS)•METAPHORS: DIRECT COMPARISON BETWEEN TARGET SYSTEM AND SOMETHING KNOWN TO USER (DESKTOP)•GLASS BOX: ATTEMPTS TO REPRESENT INTERNAL SUBSYSTEMS (STORAGE FILE CABINETS)

159

MENTAL MODELS XIIMODEL TYPES 2

•NETWORK: SYSTEM STATES, USER STATES, AND TRANSITION CONDITIONS•PROBLEM: A FLOW CHART IS LIKE A PIPELINE (GAS/WATER/USER KNOWLEDGE)

160

MENTAL MODELS XIIIINFERENCES

•GOMS (SEQUENCE/METHOD) APPROACHES CAN PREDICT EFFORT BUT NOT ERRORS. CAN PREDICT USE OF KNOWLEDGE•MENTAL MODELS EXPLAIN ERRORS AND BEHAVIOUR IN NOVEL SITUATIONS•LEARNING INVOLVES: INTERNALIZATION, ELABORATION, AND CONSTRUCTION•EXPLANATIONS OF CALCULATORS VARY WIDELY EVEN BY PEOPLE WHO USE THEM.

161

MENTAL MODELS XIVINFERENCES

•UNIX: 20 OF 400 COMMANDS ACCOUNT FOR 70% OF USAGE (LOCAL TASK VIEWS)•EXTENSIVE USAGE DOES NOT LEAD TO POWER USE OF SYSTEM (WITHOUT METAPHOR?)

162

MENTAL MODELS XVLEARNING

•IF DESIGN IS BASED UPON A MODEL THEN USER CAN BE TRAINED BY TEACHING THE MODEL•TEACHING A CALCULATOR BY EXPLAINING INTERNAL MODEL•SAME ON STANDARD TASKS•BETTER FOR NOVEL TASKS

•SOME INDICATION BETTER LEARNING IF METAPHOR FORCES ACTIVE LEARNING•READING UNDERSTOOD BETTER IF GOALS PRIOR TO DETAILS IN STORIES

163

MENTAL MODELS XVIMETAPHOR EXAMPLES 1

•TYPEWRITER (WORDPROCESSING)•DOCUMENT (GML, PAGEMAKER)•OUTLINE (THINKTANK)•CHALKBOARD•NOTECARDS (HYPERTEXT)•DESKTOP (STAR, LISA, ETC.)•DESKTOP TOOLS (SIDEKICK)•DASHBOARD•BUSINESS FORMS

164

MENTAL MODELS XVIIMETAPHOR EXAMPLES 2

•TABLES OF DATA•SPREADSHEETS•BUILDINGS•THEATRE•ROADMAP•LETTERS•POST OFFICE•SPACES•TOOLS

165

MENTAL MODELS XVIIIPROBLEMS 1

•METAPHORS OFTEN INCOMPLETE ANALOGY•MISMATCHES PROVIDE PROBLEMS (DESTRUCTIVE BACKSPACE)•PAPER FORM ON SCREEN MAY RESTRICT INPUT TO FIELDS, NO MARKING•HOWEVER, CAN VERIFY DATA

166

MENTAL MODELS XIXPROBLEMS 2

•METAPHORS OFTEN APPLIED UNEVENLY•METAPHORS CAN BE MORE THAN PHYSICAL WORLD (GAMES)•METAPHORS CAN BE MISLEADING•STRUCTURE OF ATOM = STRUCTURE OF SOLAR SYSTEM

167

MENTAL MODELS XXCOGNITIVE STATES

•COGNITIVE STATES OF METAPHOR USE•INSTANTIATION: AUTOMATIC ACTIVATION PROCESS, USUALLY BASED UPON SIMILARITY•MISMATCHES STIR ELABORATION

•ELABORATION: MAPPING STRUCTURE BY GOAL MATCHING AND CHECKING INFERENCES•CONFIRMATION OF INFERENCES LEAD TO CONSOLIDATION

•CONSOLIDATION: CREATION OF MODEL, CONDENSING INTO SINGLE REPRESENTATION

168

MENTAL MODELS XXIPROPERTIES

•PROPERTIES OF METAPHORS•BASE SPECIFICITY: DEGREE TO WHICH IT SPECIFIES THE TARGET•CLARITY: DEGREE OF ONE TO ONE CORRESPONDENCE•ABSTRACTION: DEGREE OF GENERALITY•RICHNESS: EXPANDABILITY•BASE EXHAUSTIVENESS: COVERS WHOLE OF TARGET

169

MENTAL MODELS XXIIDESIGNING METAPHORS

•IDENTIFY CANDIDATE METAPHORS•DETAIL METAPHOR / SOFTWARE MATCH•USE REPRESENTATIVE USER SCENARIOS•IDENTIFY MISMATCHES•IDENTIFY DESIGN STRATEGIES TO HELP USERS•MANAGE MISMATCHES•TO DESCRIBE METAPHOR:•TASKS: WHAT PEOPLE DO•METHODS: OBJECTS, ACTIONS•APPEARANCE: LOOK AND FEEL

170

MENTAL MODELS XXIIIEXAMPLE 1

•SCENARIO:•METAPHOR: REMOVE DOCUMENT FROM A FOLDER TO VIEW•TARGET: REMOVE FILE FROM A FILE DIRECTORY TO VIEW

•METHODS:•METAPHOR: OPEN FOLDER BY PULLING BACK FOLDER COVER•TARGET: OPEN FOLDER BY DOUBLE CLICKING FOLDER ICON

171

MENTAL MODELS XXIVEXAMPLE 2

•APPEARANCE:•METAPHOR: 3-D PAPER FOLDER THAT UNFOLDS•TARGET: 2-D ICON THAT EXPANDS INTO 2-D WINDOW

172

MENTAL MODELS XXVLEARNING MODEL 1

•COGNITIVE APPRENTICESHIP THEORY•I. BEGIN WITH TASK EMBEDDED IN FAMILIAR ACTIVITY (BY EXAMPLE)•PROVIDES SCAFFOLDING FOR UNFAMILIAR TASK

•II. POINT TO DIFFERENT DECOMPOSITIONS•STRESSES HEURISTICS ARE NOT ABSOLUTE

173

MENTAL MODELS XXVILEARNING MODEL 2

•III. ALLOW LEARNER TO GENERATE THEIR OWN PATHS•ENCULTURATING/SITUATED COGNITION

174

MENTAL MODEL XXVIIDOCUMENTATION

•MINIMAL MANUAL•FOCUS ON REAL TASKS NOT OVERVIEWS•DON'T EXPLAIN MENU BUT SHOW HOW TO CREATE A MESSAGE•EXPLAIN PRINCIPLE ERRORS USERS MAKE AS DETERMINED BY PROTOCOL ANALYSIS•COORDINATE WRITING WITH THE USE OF THE SCREENS•"CAN YOU FIND THIS PROMPT ON THE SCREEN?"

175

MENTAL MODELS XXVIIICOGNITIVE 1

•DIFFICULT CONSTRUCTING COMMANDS THAT ARE "NATURAL"•NATURAL IMPLIES EXISTENCE OF GOAL-ACTION ASSOCIATION•COMMAND HIERARCHY IS ONE APPROACH•GET.LIST•GET.SCAN•GET.VIEW

176

MENTAL MODELS XXIXCOGNITIVE 2

•NUMBER OF RULES TO DECOMPOSE A GOAL INTO SUBGOALS AND TO EXECUTE THE SEQUENCE OF ACTIONS PREDICTS LEARNING TIME•LEARNING PROGRAM LANGUAGE = 200-500 HOURS•NUMBER OF THOUGHTS TO CONSTRUCT NEXT ACTION PREDICTS DELAY•AMOUNT NEEDED IN SHORT TERM MEMORY PREDICTS ERRORS

177

MENTAL MODELS XXXCOGNITIVE 3

•VISUAL LAYOUT FOUND TO BE VERY IMPORTANT AND NOT PREDICTED BY GRAMMAR RULES•REDUCE NUMBER OF RULES NEED IS AN OBJECTIVE•DELETING SENTENCE SAME RULE AS DELETING PARAGRAPH

•TRAINING WHEELS: INTRODUCE ONLY SUBSET OF SYSTEM

178

MENTAL MODELS XXXICOGNITIVE 4

•METAPHORS SHOULD NOT BE MECHANISTIC•WHETHER OR NOT SYSTEM USES METAPHOR IN THE DESIGN THE USER WILL FORMULATE ONE•MAIL METAPHOR AN EXAMPLE OF LIMITING THE UNDERSTANDING OF WHAT IS POSSIBLE

179

MENTAL MODELS XXXIIOBSERVATION

•"METAPHORS ARE NOT JUST GOOD OR BAD DESCRIPTIONS OF THEIR TARGETS, RATHER THEY ARE STIMULATING OR UNSTIMULATING INVITATIONS TO SEE TARGET DOMAIN IN A NEW LIGHT." CARROL

181

COGNITIVE PROPERTIES


182

THE MAGIC NUMBER 7+-2

•MILLER (1956)•CHUNKING•1776149219181941

•LIMITED CHANNEL CAPACITY•SHORT TERM MEMORY•INFORMATION THEORY•LEARNING STRATEGIES•PEOPLE REORGANIZE INFORMATION TO OVERCOME LIMITATIONS

183

THE MAGIC NUMBER 7+-2

•EXAMPLES•THE SEVEN SEAS•THE SEVEN WONDERS OF THE WORLD•THE SEVEN SINS

184

RECIPROCAL RELATIONSHIP

•COGNITIVE PSYCHOLOGY•INFORMATION PROCESSING•MEMORY MODELS•LEARNING THEORIES•LANGUAGE PROCESSING•IMAGE PROCESSING•ORGANIZATION AND CLUSTERING•LEVELS OF MEMORY

185

HUMAN FACTORS AND ENGINEERING

•STIMULUS RESPONSE MODELS•PERCEPTION PROCESSING•SIGNAL/NOISE RELATIONSHIPS•PHYSIOLOGICAL RESPONSES•SIGNAL DETECTION THEORY•CHOICE REACTION TIME•DECISION PERFORMANCE•STRESS REACTIONS•FILTERING

•MAN-MACHINE SYSTEMS

186

COMMUNICATIONS AND INFORMATION THEORY

•COMMUNICATION CHANNELS•CAPACITY•CODING

•SERIAL AND PARALLEL PROCESSING•UNCERTAINTY AND AMBIGUITY•SUBJECTIVE INFORMATION MEASURES

187

MORSE CODE CODING

• LETTER CODE PROBABILITY

• E * .131• T - .105• A *- .082• X *-** .0012• Z **** .0008

188

THE THIRD METAPHORCOMPUTER ANALOGY TO

THINKING•GENERALITY OF PURPOSE•ALGORITHMS, SUBROUTINES AND COMPILERS•CONDITIONAL INSTRUCTIONS AND DECISION MAKING•SIMULATION•STRUCTURAL THEORY•SYMBOL MANIPULATION•LEVELS OF ABSTRACTION•PROGRAMS AND INTERNAL STORAGE•THEORIES OF LANGUAGE AND KNOWLEDGE

189

AN INFORMATION PROCESSING SYSTEM

•ENVIRONMENT•RECEPTORS, EFFECTORS, PROCESSOR, MEMORY

•SYMBOLS•STRUCTURE•SET OF RELATIONSHIPS•REFERENCES OBJECT•PROGRAM OR INTERPRETER

•MEMORY•RETAINS SYMBOL STRUCTURES•REPRESENTATION

190

SYSTEM CONCEPTS

•INFORMATION FLOW•DECOUPLING•HIERARCHICAL STRUCTURE•NETWORKING STRUCTURE•ASSOCIATIVE STRUCTURE

191

CHOICE REACTION TIME (CRT)SERIAL PROCESSING MODE

•STIMULUS PREPROCESSED•STIMULUS COMPARED UNTIL CATEGORIZED•CATEGORISATION IS BASIS FOR RESPONSE SELECTION•SUBJECT PROGRAMS HIS RESPONSE EXECUTION•PROPORTIONAL TO LOG OF CHOICES•CONSISTENT WITH INFORMATION THEORY•40 MSEC PER ITEM, 400 MSEC INITIAL SETUP

192

SERIAL AND PARALLEL PROCESSING

•CRT SERIAL•TYPING AND PHONE NUMBERS PARALLEL•SCANNING FOR:•(K, Z), OR (K, O), OR (O, C)•K OR (K,Z) SAME TIME•(K, O) DOUBLE TIME

•PREPROCESSORS FOR SENSES•PEOPLE SCANNING NEWSPAPERS•SPEED INDEPENDENT OF NUMBER OF CLIENTS

193

SPEED-ACCURACY TRADE-OFF

•EXTREME ACCURACY EMPHASIS•SLOW, MAXIMUM ACCURACY

•EXTREME SPEED EMPHASIS•FAST, VERY LOW ACCURACY

•HUMANS CAN CHOOSE TRADEOFF POINT•SIGNAL DETECTION THEORY

194

SIGNAL DETECTION THEORY I

•HUMAN SETS:•UPPER THRESHOLD•FAST POSITIVE RESPONSE•SMALL NUMBER OF FALSE ALARMS

•LOWER THRESHOLD•FAST NEGATIVE RESPONSE•SMALL NUMBER OF MISSES

195

SIGNAL DETECTION THEORY II

•BETWEEN THRESHOLDS•MEMORY SEARCH YIELDING•SLOWER POSITIVE AND NEGATIVE RESPONSES

•FAMILIARITY IS THE X AXIS•LEARNING EFFECTS

196

RECOGNITION DECISION FLOW

•STIMULUS PRESENTED•ENCODING AND ACCESS TO•FAMILIARITY VALUE•RESPOND IMMEDIATELY•NO: EXHAUSTIVE SEARCH

•YES: ACTIVATE RESPONSE•RESPONSE OUTPUT•HUMAN PERFORMANCE CAN BE INFLUENCED

design of interactive systems

Technology

magic number

interface

protocol analysis

mental models

data driven

interface

implementation

mass destruction