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

SIMS 213: User Interface Design & Development

Marti HearstThurs, Feb 13, 2003

Project TimelineFe

brua

ry 4

Apr

il 3

Apr

il 17

May

13

Proj

ect I

dea

Pers

onas

, Int

ervi

ews,

Task

s Ana

lysis

Low

-fi U

ser T

est

UI P

roto

type

#1

Heu

ristic

Eva

luat

ion

UI P

roto

type

#2

Use

r Tes

ting

UI P

roto

type

#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

backright

frontleft

backleft

frontright

24 possibilities, requires: -visible labels -memory

arbitrary full mapping

back front 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


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


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


Mental Models

Mental models built from– affordances– constraints– mappings– positive transfer – cultural associations/standards– instructions– interactions

Mental models are often wrong!


Our mental models of how bicycles workcan “simulate” this to know it won’t work

People are always trying to make sense of things

Mental models often extracted from fragmentary evidencePeople 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 actionsEvaluation has three stages:– Perceive world– Interpret what was perceived– Compare with respect to original intentions

Action Cycle

Goals

EvaluationEvaluation of interpretations

Interpreting the perception

Perceiving the state of the world

ExecutionIntention 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!


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


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 toolis 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 systemCentral 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)


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


Direct manipulation

Representation directly determines what can manipulated


Games


Is direct manipulation the way to go?

Some Disadvantages– Ill-suited for abstract operations

• spell-checker?Tedium

• manually search large database vs queryTask domain may not have adequate physical/visual metaphorMetaphor 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”)


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


“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: http://www.jjg.net/ia/visvocab/

– Use design guidelines to help make decisions– Create low-fi prototypes to quickly assess the different designs

http://www.jjg.net/ia/visvocab/

Design GuidelinesThere 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


1 Simple and natural dialogue

Use the user’s conceptual modelMatch 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


2 Speak the users’ language


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!)


3 Minimize user’s memory load


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


3: Minimize user’s memory load


4: Be consistent

Consistency of effects– same words, commands, actions will always have the same effect in

equivalent situationsConsistency 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


4. Be Consistent

These are labels with a raised appearance.

Is it any surprise that people try and click on them?


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?

> DoitThis will take5 minutes...

Time for

coffee.


5. Provide feedback

Should be as specific as possible, based on user’s inputBest within the context of the action


5. Provide feedback

What did I select?

What mode am I in now?

How is the system

interpreting my actions?


Provide feedback

Drawing Board LT

Multiple files being copied, but feedback is file by file.


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


How do I get

out of this?

6. Provide clearly marked exits


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)


7. Provide shortcuts

Experienced users should be able to perform frequently used operations quicklyStrategies:– 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 andpalettes 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


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


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.


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?


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...


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


Types of help

Reference manuals– used mostly for detailed lookup by experts– on-line hypertext

• search / find• table of contents• index• cross-index


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


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


Types of help

Wizards– walks user through typical tasks– but problematic if user gets stuck


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 optionsYour 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

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

Documents

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