Principles of User-Centered Design

Principles of User-Centered Design

CSCI 4800/6800

Feb. 1, 2006

What is design?

Finding the right components of a physical structure A goal-directed problem-solving activity Simulating what we want to make or do before we

make or do it – as many times as may be necessary to feel confident in the final result

Engineering design: “the use of scientific principles, technical information and imagination in the definiton of a mechanical structure, machine or system to perform pre-specified functions with the maximum efficiency and economy.

Approaches

Formal specifications Custom crafted / creative

User-Centered Design

Principles– Make user issues central in the design process– Carry out early testing and evaluation with users– Design iteratively

Methods for UCD

Soft Systems Methodology (SSM) Open Systems Task Analysis (OSTA) Multiview Star Life Cycle

Soft Systems Methodology

Focuses on planning Approach developed by Checkland, Schloes

’81, ’91 Emphasis : understand the problem and its

situation

SSM

Stages in SSM

Stages 1 and 2 – obtain “rich expression” of the problem: meetings with stakeholders

Stage 3 – obtain precise definition of the system

Stage 4 – produce conceptual models: abstract representation, “root definition”

SSM, “root definition”

• C - Clients (people who will benefit/suffer) • A - Actors (who is involved with system) • T - Transformation (purpose) • W - Weltanschauung/World View

(perspective from which root definition is formulated)

• O - Owners (who has commissioned system) • E - Environment

SSM

Stage 5 – compare “root definition” of stage 4 with “rich expression” of stage 2; iterate until gaps are filled

Stage 6 – identify changes Stage 7 – recommend an action

SSM

Benefits for HCI engineering:– Identifies people, constraints, view of system– Develops conceptual models

Cooperative Design

Participative design – users participate in design process

Sociotechnical design – considers both social and technical alternatives/solutions to/ aspects of problems

OSTA – Open Systems Task Analysis (Eason, Harker ’89)

OSTA

OSTA

Specified together:– Technical requirements

System structure, functionality

– Social system requirements Usability, acceptability

Goal:– Provide method for understanding what occurs

when computer system is introduced into a working environment

OSTA – Systems Analysis (top)

1. Primary task stated (goals of group of workers identified) 2. Task inputs identified - usually come from outside the system - character of inputs

may vary & affect way system behaves 3. External environment - including physical environment, economic, political

conditions, demand for task output 4. Transformation processes described typically - object/action flowchart of objects

to be transformed & actions neccessary to transform them with annotations

OSTA – technical and social

5. Social system analyzed • Roles of people in relation to one another • Characteristics & qualities of users of new system

6. Technical system analyzed - how will new system be integrated with others systems & what remains of the old system?

7. Performance satisfaction – for social system under new technical systems

8. Requirements for new technical system, based on the task analysis• Functionality, usability, acceptability

Problems:

Need expert to guide the design process Ability to integrate with other design

processes/methods Need “right” organizational and political climate Cost-effective???

Multiview

Combines sociotechnical and soft-systems approaches Stage 1: create PTM (primary task model) – similar to

“root def” Stage 2: conceptual modeling of info flows/ structure,

produce FM (functional model), ER model, dataflow models

Stage 3: design people tasks (PT), role sets (RS), and computer task requirements (CTR)

Stage 4: design the HCI Stage 5: technical design

Multiview

Multiview

Provides more direction for system designers

Star Life Cycle

No prescribed ordering of activities Based on actual design practive of HCI

designers Emphasis on prototyping and evaluation Rapid prototyping, incremental development

The Star Life Cycle

Star Life Cycle

Conceptual design – what is required? What should system do? What data is required? What will users need to know?

Physical design (formal design) : how to achieve the conceptual design …

Methods for UCD

Example: Olympic Messaging Service (1984 Los Angeles Olympic Games)

Kiosks at which athletes could send & receive voice messages among themselves

Or people from around the world could send messages in to athletes & official

Twelve languages (no translation)

OMS - Process

Paper scenarios of user interface prepared – Comments from designers, management, prospective

users – Some functions altered, others dropped

Brief user guides prepared, tested, developed iteratively (~200 iteratives)

– Simulations constructed & evaluated; help messages designed

– Simulations tested with users

OMS - Process

Needed to add undo/backup button Visit to village site, demos & interviews with

ex-olympians & others involved Prototype developed & tested

– "Hallway" method to collect info on height & layout of prototype kiosk

– "Try-to-destroy-it" tests of robustness (CS students)

OMS – summary

Focus on users & tasks early in design process, including user guides, help, & ensuring that user's cognitive, social, & attitudinal characteristics are understood & accomodated

Measure reactions by using prototype manuals, interface, & other simulations of the system

Design iteratively All usability factors must evolve together and be

under the responsibility of one control group

Example: Air Traffic Control System

Original system – Variety of info needed, each from own source -

some on desk, some on ceiling, some not in line of sight

– Dials – Closed Circuit TV – Temporary instructions

Air Traffic Control

Desire: Integrated data display system SAFETY (major concern) "Upgradeable" Variety of airports/local requirements Modified info requirements Layouts specific to controller & task More color Ability to add pages for specific local conditions Simple editing facilities for updates

Example – Air Traffic Control System

Process:– Evaluate controller’s task– Develop first-cut design– Establish user-systems design group– Concept testing, user feedback– Produce upgraded prototype– Road-show to five airports– Develop systems specification– build and install system– establish new needs