Human Computer Interaction - Summary

Nadine BarthJoren Vandelaer

April 1, 2012

Chapter 1

Introduction

1.1 Usability of Interactive Systems

1.1.1 User Interface Development Process

1. Design Discovery Costumers (who, what, context), Marketing, Technology, Design(what the UI is for, not how it is to be implemented)

2. Design Exploration Storyboard, Prototyping (Build a mock-up of design so you cantest, Low fidelity techniques, Interactive prototyping tools, UI builders)

3. Evaluation Review and Iterate (Test with real customers, Build models, Low-costtechniques)

4. Production Work together ans realize the design in detail, evaluate with costumers

1.1.2 PACT

• People (Physical, Psychological, Social differences)

• Activities (Temporal aspects, Cooperation, Complexity, Safety-Critical, Nature of thecontent)

• Contexts (Physical Environment, Social Context, Organizational Context)

• Technologies (Input, Output, Communication, Content)

Goals: promote standardization, integration, consistency, and portability

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1.1.3 Usability measures

• Define the target user community and class of tasks associated with the interface

• Communities evolve and change (e.g. the interface to information services for the U.S.Library of Congress)

• 5 human factors central to community evaluation:

1. Time to learn

2. Speed of performance

3. Rate of errors by users

4. Retention over time

5. Subjective satisfaction

• Trade-offs in design options frequently occur

• Design alternatives can be evaluated by designers and users via mockups or high-fidelityprototypes

1.2 Guidelines, Principles, and Theories

1.2.1 Guidelines

Accessibility Guidelines

• Provide a text equivalent for every nontext element

• For any time-based multimedia presentation synchronize equivalent alternatives

• Information conveyed with color should also be conveyed without it

• Title each frame to facilitate identification and navigation

Smith and Mosier (1986) offer five high-level goals: Consistency of data display, Efficientinformation assimilation by the user, Minimal memory load on the user, Compatibility ofdata display with data entry, Flexibility for user control of data display

1.2.2 Principles

Principles are more fundamental, widely applicable, and enduring than guidelines qnd needmore clarification. Fundamental principles determine the user’s skill level and identifies thetasks.

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The user’s skill level has to be determined (we have to know the user): Age, gender,physical and cognitive abilities, education, cultural or ethnic background, training, motiva-tion, goals and personality. The design goals have to be based on the skill level of the user(novice or first-time users, knowledgeable intermittent users, expert frequent users). Thedesign could be made multi-layer.

The tasks have to be identified with PACT (see section 1)

The 8 golden rules of interface design

1. Strive for consistency

2. Cater to universal usability

3. Offer informative feedback

4. Design dialogs to yield closure

5. Prevent errors

6. Permit easy reversal of actions

7. Support internal locus of control

8. Reduce short term memory load

Preventing Errors

Preventing errors is very important in the process of Interface Design.The error messages must be specific, positive in tone and constructive. It has to correct

actions by for example graying out inappropriate actions, automatic completion or selectionrather than freestyle typing.

Complete sequences play an important role in error prevention: single abstract com-mands, macros and subroutines.

Automation and human control

With the successful integration, users can avoid routine, tedious and error prone tasks andcan concentrate on making critical decisions, coping with unexpected situations and planningfuture actions. User modeling for adaptive interfaces keeps track of the user performance,adapts behavior to suit user’s needs and allows for automatically adapting system (responsetime, length of messages, density of feedback, content of menus, order of menu items, typeof feedback, content of help screens). But it can also be problematic; the system may makesurprising changes, the user must pause to see what has happened or the user may not beable to predict the next changes, interpret what has happened or restore the system to itsprevious state.

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1.2.3 Theories

Theories should be more central to research and practice. Theories should lead rather thanlag behind practice.

Design by levels

Foley and van Dam four-level approach:

• Conceptual level (User’s mental model of the interactive system )

• Semantic level (Describes the meanings conveyed by the user’s command input and bythe computer’s output display )

• Syntactic level (Defines how the units (words) that convey semantics are assembledinto a complete sentence that instructs the computer to perform a certain task )

• Lexical level (Deals with device dependencies and with the precise mechanisms bywhich a user specifies the syntax )

This approach is very convenient for designers because the top-down nature is easy toexplain, it mathches the software architecture and it allows for useful modularity during thedesign.

Stages of action models

Another approach to forming explanatory theories is to portray the stages of action thatusers go through in trying to use interactive products.

Norman’s seven stages of action:

1. Forming the goal

2. Forming the intention

3. Specifying the action

4. Executing the action

5. Perceiving the system state

6. Interpreting the system state

7. Evaluating the outcome

Four principles of good design:

• State and the action alternatives should be visible

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• Should be a good conceptual model with a consistent system image

• Interface should include good mappings that reveal the relationships between stages

• User should receive continuous feedback

Four critical points where user failures can occur

• Users can form an inadequate goal

• Might not find the correct interface object because of an incomprehensible label or icon

• May not know how to specify or execute a desired action

• May receive inappropriate or misleading feedback

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Chapter 2

Development Process

2.1 Managing Design Processes

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2.1.1 The four pillars of Design

1. User Interface Requirements: Soliciting and clearly specifying user requirementsis a major key to success in any development activity. Laying out the user-interfacerequirements is part of the overall requirements development and management process.The user interface requirements describe the system behavior.

Ethnographic Observation: Identifying and observing the user community in action(preparation, field study, analysis, reporting)

2. Guidelines, Documents and Process: Each project has different needs, but guide-lines should be considered for: words, icons and graphics. Screen Layout issues andinput and output devices need to be respected. Action sequences and Training.

3. User interface software tools: UI builder tools are used to vizualize the interfacesince it is difficult for users to imagine what a system will look like and major changesare expensive.

4. Expert Reviews and Usability Testing: The system has to be tested (Like re-hersals in theater).

2.1.2 Participatory Design

Include End users in the design process

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• Immerse Users in the subject before the session (give users probe packs with diaries,cameras, pens, instructions)

• Encourage users to annotate paper copies of your design scribble on paper copies)

• Allow users to create “Frankenstein’ designs (taking the best aspects of different de-signs)

• Ask users to personify the product (imagine the product as a person and describe itin words and pictures)

• Continue communicating about the subject with users (Continue discussion after prod-uct is finished like with a user community)

2.2 Evaluating interface Designs

2.2.1 Expert Reviews

It i sosmetimes helpful that an expert reviews the design. He can do that on different lev-els: Heuristic evaluation, Guidelines review, Consistency inspection, Cognitive walkthrough,Metaphors of human thinking or Formal usability inspection. It takes them between half aday and a week altough a longer training period may be required.

Expert reviews can be scheduled at several points in the development process whenexperts are available and when the design team is ready for feedback. Different experts tendto find different problems in an interface, so 3-5 expert reviewers can be highly productive, ascan complementary usability testing. The dangers with expert reviews are that the expertsmay not have an adequate understanding of the task domain or user communities. Evenexperienced expert reviewers have great difficulty knowing how typical users, especially first-time users will really behave.

Ten Usability Heuristics by Jakob Nielsen

1. Visibility of system status: The system should always keep users informed aboutwhat is going on, through appropriate feedback within reasonable time.

2. Match between system and the real world: The system should speak the users’language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a naturaland logical order.

3. User control and freedom: Users often choose system functions by mistake and willneed a clearly marked ”emergency exit” to leave the unwanted state without havingto go through an extended dialogue. Support undo and redo.

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4. Consistency and standards: Users should not have to wonder whether differentwords, situations, or actions mean the same thing. Follow platform conventions.

5. Error prevention: Even better than good error messages is a careful design whichprevents a problem from occurring in the first place. Either eliminate error-proneconditions or check for them and present users with a confirmation option before theycommit to the action.

6. Recognition rather than recall: Minimize the user’s memory load by making ob-jects, actions, and options visible. The user should not have to remember informationfrom one part of the dialogue to another. Instructions for use of the system should bevisible or easily retrievable when appropriate.

7. Flexibility and efficiency of use: Accelerators - unseen by the novice user - mayoften speed up the interaction for the expert user such that the system can cater toboth inexperienced and experienced users. Allow users to tailor frequent actions.

8. Aesthetic and minimalist design: Dialogues should not contain information whichis irrelevant or rarely needed. Every extra unit of information in a dialogue competeswith the relevant units of information and diminishes their relative visibility.

9. Help users recognize, diagnose, and recover from errors: Error messages shouldbe expressed in plain language (no codes), precisely indicate the problem, and construc-tively suggest a solution.

10. Help and documentation: Even though it is better if the system can be usedwithout documentation, it may be necessary to provide help and documentation. Anysuch information should be easy to search, focused on the user’s task, list concretesteps to be carried out, and not be too large.

2.2.2 Usability Laboratories

The emergence of usability testing and laboratories since the early 1980s. Usability testingnot only sped up many projects but that it produced dramatic cost savings. The movementtowards usability testing stimulated the construction of usability laboratories. A typicalmodest usability lab would have two 10 by 10 foot areas, one for the participants to dotheir work and another, separated by a half-silvered mirror, for the testers and observers.Participants should be chosen to represent the intended user communities, with attention tobackground in computing, experience with the task, motivation, education, and ability withthe natural language used in the interface.

Videotaping participants performing tasks is often valuable for later review and for show-ing designers or managers the problems that users encounter.

Many variant forms of usability testing have been tried: Paper mockups, Discount usabil-ity testing, Competitive usability testing, Universal usability testing, Field test and portablelabs, Remote usability testing and Can-you-break-this tests.

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2.2.3 Surveys

Written user surveys are a familiar, inexpensive and generally acceptable companion forusability tests and expert reviews. In order to have a successful survey, the goals have tobe clear in advance and there has to be a development of focused items that help attainthe goals. Survey goals can be tied to the components of the Objects and Action Interfacemodel of interface design. Users could be asked for their subjective impressions about specificaspects of the interface. Online surveys avoid the cost of printing and the extra effort neededfor distribution and collection of paper forms. Many people prefer to answer a brief surveydisplayed on a screen, instead of filling in and returning a printed form.

2.2.4 Acceptance Test

For large implementation projects, the customer or manager usually sets objective and mea-surable goals for hardware and software performance. If the completed product fails to meetthese acceptance criteria, the system must be reworked until success is demonstrated.

Rather than the vague and misleading criterion of ”user friendly,” measurable criteriafor the user interface can be established for the following: Time to learn specific functions,Speed of task performance, Rate of errors by users, Human retention of commands over timeand Subjective user satisfaction.

2.2.5 Evaluation during active use

Successful active use requires constant attention from dedicated managers, user-servicespersonnel, and maintenance staff.

Continuous user-performance data logging: The software architecture should make iteasy for system managers to collect data about the patterns of system usage, the speed ofuser performance, the rate of errors and the frequency of request for online assistance. Amajor benefit is guidance to system maintainers in optimizing performance and reducingcosts for all participants.

Online or telephone consultants, e-mail, and online suggestion boxes: Many usersfeel reassured if they know there is a human assistance available. On some network systems,the consultants can monitor the user’s computer and see the same displays that the usersees.

Online suggestion box or e-mail trouble reporting: Electronic mail to the maintainersor designers. For some users, writing a letter may be seen as requiring too much effort.

Discussion groups, wiki?s and newsgroups: Permit postings of open messages andquestions, some are independent, e.g. America Online and Yahoo!, topic list, sometimesmoderators, Social systems, comments and suggestions should be encouraged.

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Chapter 3

Interaction Styles

3.1 Direct Manipulation and Virtual Environments

3.1.1 Introduction

Positive feelings are associated with good user interfaces.

3.1.2 Examples of Direct-Manipulation Systems

Command line vs. display editors and word processors: Training times with display editorsare much less than line editors. Line editors are generally more flexible and powerful. (MSWord, VisiCalc, MS Excel, ArtView, ...)

Video Games: Field of action is visual and compelling, Commands are physical actionswhose results are immediately shown on the screen, No syntax to remember, Most gamescontinuously display a score. (Guitar Hero, ...)

3.1.3 Discussion of Direct Manipulation

Problems with direct manipulation:

• Spatial or visual representations can be too spread out

• High-level flowcharts and database-schema can become confusing

• Designs may force valuable information off of the screen

• Users must learn the graphical representations

• The visual representation may be misleading

• Typing commands with the keyboard may be faster

Principles of Direct Manipulation

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1. Continuous representations of the objects and actions of interest with meaningful visualmetaphors.

2. Physical actions or presses of labeled buttons, instead of complex syntax.

3. Rapid, incremental, reversible actions whose effects on the objects of interest are visibleimmediately.

Icons: An icon is an image, picture, or symbol representing a concept. It has to representthe object or action in a familiar manner, the number of different icons has to be limited,icons have to stand out from the background, take three-dimensional icons into consideration,ensure that a selected icon is visible from unselected icons, design the movement animation,add detailed information, explore combinations of icons to create new objects or actions.

3.1.4 3D Interfaces

?Pure? 3D interfaces have strong utility in some contexts, e.g., medical, product design.In other situations, more constrained interaction may actually be preferable to simplifyinteractions.

3.1.5 Teleoperation

This is derived from direct manipulation in personal computers and process control in com-plex environments. Complicating factors in the architecture of remote environments are timedelays, incomplete feedback, feedback from multiple sources, unanticipated interferences.

3.2 Menu Selection, Form Fill-In, and Dialog Boxes

3.2.1 Single Menus

• Binary Menus: Only two possibilities (buttons)

• Multiple-item menus: radio-button or check boxes

• Pull-down, pop-up, and toolbar menus

• Toolbars, iconic menus, and palletes

• Pop-up menus

• Menus for long lists: Scrolling menus, combo boxes, and fisheye menus, slidersand alphasliders two-dimensional menus (example: colors)

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3.2.2 Combination of Multiple Menus

• Linear (guide the user trough complex decision-making process, effective for noviceusers performing simple tasks) menu sequences and simultaneous (Present multipleactive menus at the same time and allows users to enter choices in any order) menus

• Tree-structured menus (4-8 items per menu, 4 levels max)

• Menu Maps: Menu maps can help users stay oriented in a large menu tree, effectivefor providing overviews to minimize user disorientation.

• Acyclic and Cyclic Networks: Useful for social relationships, transportation rout-ing, scientific-journal citations. Can cause confusion and disorientation.

3.2.3 Content Organization

• Task-related grouping in tree organization: Create groups of logically similaritems, form groups that cover all possibilities, make sure that items are nonoverlapping,use familiar terminology, but ensure that items are distinct from one another.

• Item Presentation Sequence: The order of items in the menu is important, andshould take natural sequence into account when possible (time, numeric ordering, phys-ical properties). When cases have no task-related orderings, the designer must choosefrom such possibilities as alphabetic sequence of terms, grouping of related items, mostfrequently used items first or most important items first.

• Menu Layout

– Titles: For single menus, use a simple descriptive title. For tree-structured menus,use the exact same words in the higher-level menu items as in the titles for thenext lower-level menu.

– Graphic layout and design: contstraints (screen size, display rate,...)

– Establish guidelines for consistency of at least these menu components: Titles, itemplacement, instructions, error messages, status reports.

3.2.4 Fast Movement Through Menus

Fast movement trough Menus by keyboard shortcuts.

3.2.5 Data Entry

• Form Fill-in: Appropriate when many fields of data must be entered. Includes format-specific field

• Dialog Boxes: Combination of menu and form fill-in techniques

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• Alternatives: Pie menus (example here), Control menus, Marking menus, Flowmenus, Toolglass, audio menus,

3.2.6 Audio Menus and Small Displays

Voice recognition etc.

3.3 Command and Natural Languages

3.3.1 Introduction

The Basic Goals of Language Design

• Precision

• Compactness

• Ease in writing and reading

• Speed in learning

• Simplicity to reduce errors

• Ease of retention over time

Higher-Level Goals of Language Design

• Close correspondence between reality and the notation

• Convenience in carrying out manipulations relevant to user’s tasks

• Compatibility with existing notations

• Expressiveness to encourage creativity

• Flexibility to accommodate novice and expert users

• Visual appeal

3.3.2 Command-Organization Strategies

Designers often err by choosing a metaphor closer to machine domain than to the user’s taskdomain. Each command is chosen to carry out a single task. The number of commandsmatch the number of tasks. For small number of tasks, this can produce a system easy tolearn and use.

Error rates and the need for extensive training increase with the number of possibleoptions.

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3.3.3 The bebefits of structure

Human learning, problem solving, and memory are greatly facilitated by meaningful struc-ture. Qrgument ordering hqs to be consistent!!

Hierarchial command structure: The full set of commands is organized into a tree struc-ture.

Symbols versus Keywords

3.3.4 Naming and Abbreviations

There is often a lack of consistency or obvious strategy for construction of command abbre-viations. (Specificity Versus Generality)

Six Potential Abbreviation Strategies

1. Simple truncation: The first, second, third, etc. letters of each command.

2. Vowel drop with simple truncation: Eliminate vowels and use some of what remains.

3. First and last letter: Since the first and last letters are highly visible, use them.

4. First letter of each word in a phrase: Use with a hierarchical design plan.

5. Standard abbreviations from other contexts: Use familiar abbreviations.

6. Phonics: Focus attention on the sound.

3.3.5 Natural Language in Computing

Natural-language queries and question answering, Alice Chatbot, Star-Trek scenario,...

3.3.6 Speech and auditory interfaces

Speech recognition still does not match the fantasy of science fiction.

• Continuous-speech recognition: Not generally available (difficulty in recognizingboundaries between spoken words, normal speech patterns blur boundaries, many po-tentially useful applications if perfected)

• Speech store and forward: Voice mail users can receive messages, replay messages,replay to caller, forward messages, delete messages, archieve mesages. Systems are lowcost and reliable.

• Audio tones, audiolization, and music: Sound feedback can be important (warn-ings,...)

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3.4 Interaction Devices

Qwerty vs. Dvorak vs. ABCDEKeyboards and keypads for small devices: Wireless or foldable keyboards, Virtual key-

boards, Cloth keyboards, Soft keys, Pens and touchscreens. Strange things: Orbitouch,typing with mouse, Palm device, ...

Pointing devices

Pointing devices are applicable in six types of interaction tasks: (Foley et al., 1984)

1. Select

2. Position

3. Orient

4. Path

5. Quantify

6. Text

Direct Control pointing devices: lightpen, touchscreen, Tablet PCs and mobile Devices.Indirect Pointing devices: Mouse, trackball, joystick, graphics tablet, touchpad.

Comparison of pointing devices

Human-factors variables: speed of motion for short and long distances, accuracy ofpositioning, error rates, learning time, user satisfactionOther Variables: cost, durability, space requirements , weight, left- versus right-hand use,likelihood to cause repetitive-strain injury, compatibility with other systemsResults: direct pointing devices faster, but less accurate, graphics tablets are appealingwhen user can remain with device for long periods without switching to keyboard, mouse isfaster than isometric joystick, for tasks that mix typing and pointing, cursor keys a fasterand are preferred by users to a mouse, muscular strain is low for cursor keys

3.4.1 Displays - Small and Large

The display has become the primary source of feedback to the user from the computer. Smallvs. large.

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3.5 Collaboration and Social Media Participation

3.5.1 Collaboration

Goals of cooperation: Focused partnerships, Lecture or demo, Conference, Structured workprocesses, Meeting and decision support, Electronic commerc, Tele-democracy, On-line com-munities, Collaboratories, Telepresence

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3.5.2 Asynchronous distributed interfaces: Different place, differ-ent time

Electronic Mail, Newsgroups, listservers, discussion boards, conferences, social media par-ticipation web sites, blogs, and wikis, network communities,...

3.5.3 Synchronous distributed interfaces: Different place, sametime

Group editing, shared screens for customer assistance, interactive games, CHAT, Twitter,Texting and cell phones, audio and video conferencing

3.5.4 Face-to-face interfaces: Same place, same time

Shared display from lecturer workstation, Audience response units, File sharing, Sharedworkspace, Group activities, Colab and Liveboard, SMART Board, Public spaces facilitatesharing, Sharing photos is very popular, Notification systems.

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Chapter 4

Design Issues

4.1 Quality of Service

4.1.1 Models of response-time impacts

Response time is the number of seconds it takes from the moment users initiate an activityuntil the computer presents results on the display. User think time is the number of secondsthe user thinks before entering the next action.

Overall majority of users prefer rapid interactions. Lengthy response times (15 seconds)are detrimental to productivity and rapid response times (1 second or less) are preferable,but can increase errors for complex tasks.

Display Rate: Alphanumeric displays (The speed in characters per second at whichcharacters appear for the user to read), World Wide Web Applications (Display rate may belimited by network transmission speed or server performance)

Reading textual information from a screen is a challenging cognitive and perceptual task.Users relax when the screen fills instantly- beyond a speed where someone may feel compelledto keep up

Cognitive human performance would be useful for: making predictions, designing sys-tems, formulating management policies.

Source of errors: Solutions to problems must be recorded to memory or implemented. Thechance of error increases when solutions are recorded. When using an interactive computersystem users may formulate plans and have to wait for execution time of each step. Long(1976) found unskilled and skilled typists worked more slowly and made more errors withlonger response times. For a given user and task, there is a preferred response time.

Longer response time causes uneasiness in the user because the penalty for error increaseswhile shorter response time may cause the user to fail to comprehend the presented materi-als. Progress indicators shorten perceived elapsed time and heighten satisfaction: graphicalindicators, blinking messages, numeric seconds left for completion.

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4.1.2 User Productivity

Users pick up the pace of the system to work more quickly with shorter response time.

4.1.3 Variability

People are willing to pay substantial amounts of money to reduce the variability in their life,e.g. insurance.

4.1.4 Frustrating experiences

Since frustration, distractions, and interruptions can impede smooth progress, design strate-gies should enable users to maintain concentration.

Three initial strategies can reduce user frustration: Reduce short-term and working mem-ory load, Provide information abundant interfaces, Increase automaticity

4.2 Information search

Information search should be a joyous experience, but it takes a skilled searcher with robusttools to perform an effective search.

What to enter? Where to search? Additional information like a table of content canhelp.

Expert uisers can use SQL. It has powerful features but requires trainng.

Five-phase framework to clarify user interfaces for textual search

1. Formulation

2. Initiation of actions

3. Review of results

4. Refinement

5. Use

4.2.1 Multimedia Document Searches

Image search (difficult), Map search, Design or diagram search, Sound search, Video search,Animation search

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4.2.2 Filtering

Filtering with complex Boolean queries, Automatic filtering, Dynamic queries, Faceted meta-data search, Query by example, Implicit search, Collaborative filtering, Multilingual searches,Visual field specification

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