SIMS 213: User Interface Design & Development Marti Hearst Thurs, Feb 13, 2003

Project Timeline February 4 April 3 April 17 May 13 Project Idea Personas, Interviews, Tasks Analysis Low-fi User Test UI Prototype #1 Heuristic Evaluation UI Prototype #2 User Testing UI Prototype #3

Mappings Mapping: –Relationships between two things Between controls and their results –Related to metaphor discussion –Related to affordances

Slide adapted from Saul Greenberg

Mapping controls to physical outcomes back right front left back left front right 24 possibilities, requires: -visible labels -memory arbitrary full mapping back front back 2 possibilities per side =4 total possibilities paired

Mappings For devices, appliances –Natural mappings use constraints and correspondences in the physical world Controls on a stove Controls on a car –Radio volume »Knob goes left to right to control volume »Should also go in and out for front to rear speakers For computer UI design –Mapping between controls and their actions on the computer Controls on a digital watch Controls on a word processor program

Based on slide by Saul Greenberg Transfer Effects People transfer their expectations from familiar objects to similar new ones –positive transfer: previous experience applies to new situation –negative transfer: previous experience conflicts with new situation

Based on slide by Saul Greenberg Cultural Associations Groups of people learn idioms –red = danger, green = go But these differ in different places –Light switches America: down is off Britain: down is on –Faucets America: counter-clockwise is on Britain: counter-clockwise is off

Based on slide by Saul Greenberg Mental Models People have mental models of how things work: –how does your car start? –how does an ATM machine work? –how does your computer boot? Allows people to make predictions about how things will work

Based on slide by Saul Greenberg Mental Models Mental models built from –affordances –constraints –mappings –positive transfer –cultural associations/standards –instructions –interactions Mental models are often wrong!

Slide adapted from Saul Greenberg Our mental models of how bicycles work can “simulate” this to know it won’t work

People are always trying to make sense of things Mental models often extracted from fragmentary evidence People find ways to explain things –Computer terminal breaks when accessing the library catalog –Certain you’re driving on the correct road

Norman’s Action Cycle Human action has two primary aspects –Execution: doing something –Evaluation: comparison of what happened to what was desired

Action Cycle Goals EvaluationExecution The World start here

Norman’s Action Cycle Execution has three stages: –Start with a goal –Translate into an intention –Translate into a sequence of actions Now execute the actions Evaluation has three stages: –Perceive world –Interpret what was perceived –Compare with respect to original intentions

Action Cycle Goals Evaluation Evaluation of interpretations Interpreting the perception Perceiving the state of the world Execution Intention to act Sequence of actions Execution of seq uence of actions The World start here

Gulf of Evaluation The amount of effort a person must exert to interpret –the physical state of the system –how well the expectations and intentions have been met We want a small gulf!

Based on slide by Saul Greenberg Example Scissors –affordances: holes for insertion of fingers blades for cutting –constraints big hole for several fingers, small hole for thumb –mapping between holes and fingers suggested and constrained by appearance –positive transfer learnt when young –conceptual model implications clear of how the operating parts work

Based on slide by Saul Greenberg Bad Example Digital Watch –affordances four push buttons, not clear what they do –contraints and mapping unknown no visible relation between buttons and the end-result of their actions –negative transfer little association with analog watches –cultural standards somewhat standardized functionality, but highly variable –conceptual model must be taught; not obvious

Digital Watch Redesigned for Affordances (Rachna Dhamija)

Digital Watch Redesigned for Affordances (Ping Yee)

Interface Metaphors Revisited Definition of Metaphor –application of name or descriptive term to an object to which it is not literally applicable Purpose –function as natural models –leverages our knowledge of familiar, concrete objects/experiences to understand abstract computer and task concepts Problem –metaphor may portray inaccurate or naive conceptual model of the system A presentation tool is like a slide projector

The Metaphor of Direct Manipulation Direct Engagement –the feeling of working directly on the task Direct Manipulation –An interface that behaves as though the interaction was with a real-world object rather than with an abstract system Central ideas –visibility of the objects of interest –rapid, reversible, incremental actions –manipulation by pointing and moving –immediate and continuous display of results Almost always based on a metaphor –mapped onto some facet of the real world task semantics)

Slide adapted from Saul Greenberg Object-Action vs Action-Object Select object, then do action –interface emphasizes 'nouns' (visible objects) rather than 'verbs' (actions) Advantages –closer to real world –modeless interaction – actions always within context of object inappropriate ones can be hidden – generic commands the same type of action can be performed on the object eg drag ‘n drop: my.doc move

Slide adapted from Saul Greenberg Direct manipulation Representation directly determines what can manipulated

Slide adapted from Saul Greenberg Games

Slide adapted from Saul Greenberg Is direct manipulation the way to go? Some Disadvantages –Ill-suited for abstract operations spell-checker? Tedium manually search large database vs query Task domain may not have adequate physical/visual metaphor Metaphor may be overly-restrictive Solution: Most systems combine direct manipulation and abstractions word processor: –WYSIWYG document (direct manipulation) –buttons, menus, dialog boxes (abstractions, but direct manipulation “in the small”)

Based on slide by Saul Greenberg Guidelines for Design Provide a good conceptual model –allows users to predict consequences of actions –communicated thorugh the image of the system Make things visible –relations between user’s intentions, required actions, and results should be sensible consistent meaningful (non-arbitrary) –make use of visible affordances, mappings, and constraints –remind person of what can be done and how to do it

Summary Good Representations –captures essential elements of the event / world –deliberately leaves out / mutes the irrelevant –appropriate for the person, their task, and their interpretation Metaphors –uses our knowledge of the familiar and concrete to represent abstract concepts –need not be literal –has limitations that must be understood Direct manipulation –visibility of the objects of interest –rapid, reversible, incremental actions –manipulation by pointing and moving –immediate and continuous display of results

Discuss Readings

Raskin on Cognition Cognitive Engineering –Ergonomics: sizes and capabilities of the human body –Cognetics: Ergonomics of the mind –This is the applied side of cognitive science

Image from Newsweek, Jan 2001 Raskin on Cognition Cognitive Conscious / Unconscious –Examples? –Differences? Locus of Attention –What is it? –Why is it important for HCI?

Cooper on error dialog boxes Why are they problematic? How related to locus of attention? What are the alternatives? –Cooper is talking to programmers “Silicon Sanctimony” You should feel as guilty as for using a goto – an admission of failure in design

What happens when you cancel a cancelled operation? Do I have any choice in this? Umm, thanks for the warning, but what should I do? Uhhh… I give up on this one

Inane Dialog Boxes

Slide adapted from Saul Greenberg “HIT ANY KEY TO CONTINUE”

Design Principles and Process

Designing the Interface How to do the design itself? –Do your task analysis –Identify the important tasks and their steps Use personas to identify the important ones Use card sorting to help organize the tasks Use scenarios to give order to the task sequences –Organize these into several different designs Get the main interactions sketched out –Make sketches, or –Use a tool, such as a flow chart –An example: –Use design guidelines to help make decisions –Create low-fi prototypes to quickly assess the different designs

Design Guidelines There are LOTS of them –Based on common sense and experience Not necessarily proven –Often conflict with one another –Often don’t say HOW to implement them What do to: –Focus on those guidelines most applicable to the kind of interface under development –Focus on those emphasized in our readings Bloopers, chapter 1 Usability Engineering, chapter 5 Raskin, chapter 3 All of Don Norman’s concerns –Use common sense

All-Star Usability Design Guidelines An edited selection

Slide adapted from Saul Greenberg 1 Simple and natural dialogue Use the user’s conceptual model Match the users’ task in as natural a way as possible –minimize mapping between interface and task semantics

1 Simple and natural dialogue Present exactly the information the user needs –less is more less to learn, to get wrong, to distract... –information should appear in natural order related information is graphically clustered order of accessing information matches user’s expectations –remove or hide irrelevant or rarely needed information competes with important information on screen –use windows frugally don’t make navigation and window management excessively complex

Slide adapted from Saul Greenberg

2 Speak the users’ language

Slide adapted from Saul Greenberg 3 Minimize user’s memory load Computers good at remembering things, people aren’t! Promote recognition over recall –menus, icons, choice dialog boxes vs command lines, field formats –relies on visibility of objects to the user (but less is more!)

Slide adapted from Saul Greenberg 3 Minimize user’s memory load

Slide adapted from Saul Greenberg 3: Minimize user’s memory load Describe required input format and example, and default Small number of rules applied universally –generic commands same command can be applied to all interface objects copy, cut, paste, drag ’n drop,... for characters, words, paragraphs, circles, files

Slide adapted from Saul Greenberg 3: Minimize user’s memory load

Slide adapted from Saul Greenberg 4: Be consistent Consistency of effects –same words, commands, actions will always have the same effect in equivalent situations Consistency of language and graphics –same information/controls in same location on all screens / dialog boxes –same visual appearance across the system (e.g. widgets) e.g. different scroll bars in a single window system! Consistency of input –consistent syntax across complete system

Slide adapted from Saul Greenberg 4. Be Consistent These are labels with a raised appearance. Is it any surprise that people try and click on them?

Slide adapted from Saul Greenberg 5: Provide feedback Continuously inform the user about –what it is doing –how it is interpreting the user’s input –user should always be aware of what is going on > Doit What’s it doing? > Doit This will take 5 minutes... Time for coffee.

Slide adapted from Saul Greenberg 5. Provide feedback Should be as specific as possible, based on user’s input Best within the context of the action

Slide adapted from Saul Greenberg 5. Provide feedback What did I select? What mode am I in now? How is the system interpreting my actions?

Slide adapted from Saul Greenberg Provide feedback Drawing Board LT Multiple files being copied, but feedback is file by file.

Slide adapted from Saul Greenberg 5. Provide feedback Response time –how users perceive delays 0.1 second max: perceived as “instantaneous” 1 seconds max: user’s flow of thought stays uninterrupted, but delay noticed 10 seconds: limit for keeping user’s attention focused on the dialog > 10 seconds: user will want to perform other tasks while waiting

Slide adapted from Saul Greenberg How do I get out of this? 6. Provide clearly marked exits

Slide adapted from Saul Greenberg 6. Provide clearly marked exits Users don’t like to feel trapped by the computer! –should offer an easy way out of as many situations as possible Strategies: –Cancel button (for dialogs waiting for user input) –Universal Undo (can get back to previous state) –Interrupt (especially for lengthy operations) –Quit (for leaving the program at any time) –Defaults (for restoring a property sheet)

Slide adapted from Saul Greenberg 7. Provide shortcuts Experienced users should be able to perform frequently used operations quickly Strategies: –keyboard and mouse accelerators abbreviations command completion menu shortcuts function keys double clicking vs menu selection –type-ahead (entering input before the system is ready for it) navigation jumps e.g., going to location directly, and avoiding intermediate nodes –history systems WWW: ~60% of pages are revisits

Keyboard accelerators for menus Customizable toolbars and palettes for frequent actions Split menu, with recently used fonts on top Scrolling controls for page-sized increments Double-click raises object- specific menu Double-click raises toolbar dialog box

Slide adapted from Saul Greenberg 8: Deal with errors in a positive and helpful manner People will make errors! Errors we make –Mistakes arise from conscious deliberations that lead to an error instead of the correct solution –Slips unconscious behaviour that gets misdirected en route to satisfying goal –e.g. drive to store, end up in the office shows up frequently in skilled behaviour –usually due to inattention often arises from similarities of actions

Slide adapted from Saul Greenberg Designing for slips General rules –Prevent errors before they occur –Detect and correct errors when they do occur –User correction through feedback and undo Examples –mode errors have as few modes as possible (preferably none) make modes highly visible –capture errors instead of confirmation, make actions undoable allows reconsideration of action by user –loss of activation if system knows goal, make it explicit if not, allow person to see path taken –description errors in icon-based interfaces, make sure icons are not too similar, check for reasonable input, etc.

Slide adapted from Saul Greenberg 8 Deal with errors in a positive and helpful manner Prevent errors –try to make errors impossible –modern widgets: only “legal commands” selected, or “legal data” entered Provide reasonableness checks on input data –on entering order for office supplies 5000 pencils is an unusually large order. Do you really want to order that many?

Slide adapted from Saul Greenberg 9. Provide help Help is not a replacement for bad design! Simple systems: –walk up and use; minimal instructions Most other systems: –feature rich –some users will want to become “experts” rather than “casual” users –intermediate users need reminding, plus a learning path Volume 37: A user's guide to...

Slide adapted from Saul Greenberg Types of help Tutorial and/or getting started manuals –short guides that people are likely to read when first obtaining their systems encourages exploration and getting to know the system tries to get conceptual material across and essential syntax –on-line “tours”, exercises, and demos demonstrates very basic principles through working examples

Slide adapted from Saul Greenberg Types of help Reference manuals –used mostly for detailed lookup by experts –on-line hypertext search / find table of contents index cross-index

Slide adapted from Saul Greenberg Types of help Reminders –short reference cards expert user who just wants to check facts novice who wants to get overview of system’s capabilities –keyboard templates shortcuts/syntactic meanings of keys; recognition vs. recall; capabilities –tooltips text over graphical items indicates their meaning or purpose

Slide adapted from Saul Greenberg Types of help Context-sensitive help –system provides help on the interface component the user is currently working with Tool tips Macintosh “balloon help” Microsoft “What’s this” help –brief help explaining whatever the user is pointing at on the screen

Slide adapted from Saul Greenberg Types of help Wizards –walks user through typical tasks – but problematic if user gets stuck

Slide adapted from Saul Greenberg Types of help Tips –migration path to learning system features –also context-specific tips on being more efficient –must be “smart”, otherwise boring and tedious

Summary Design is a creative process, with many options Your design should reflect –The results of the interviews, task analysis –Existing conventions when applicable –Design guidelines when applicable Usability testing helps you decide which of several options to pursue