User-Centred Design: Design Principles (lecture-4)

User-Centred Design:

Design Principles(lecture-4)

Prof. Dr. Matthias RauterbergFaculty Industrial Design

Technical University of Eindhoven

[email protected]

© M. Rauterberg, TU/e 2

The first most important invariant

• horizon– the horizon is always

lighter than the ground

• ground– the ground is always

darker than the horizon


The second most important invariant

• The Top– All good, strong and

important things are at the top (e.g., God in heaven, the king, the boss, etc.).

• The Bottom– All small, weak and

unimportant things are at the bottom line.


Limits of the Working Memory

100%

80%

60%

40%

20%

0 3 6 9 12 15 18

remember rate

time interval until remember items (in sec)

• working memory– remember time < 5 sec

– about 5-9 chunks

– masking

– interferences

• long-term memory– no capacity limits


Knowledge in the World and in the Head

Property Knowledge in the World Knowledge in the Head

Retrievability: Retrievability whenevervisible or audible or tangible.

Not readily retrievable.Requires memory search orreminding.

Learning: Learning not required.Interpretation substitutes forlearning.

Requires learning, which canbe considerable.

Efficiency of use: Tends to be slowed up by theneed to find and interpret theexternal information.

Can be very efficient.

Ease of use atfirst encounter:

High. Low.

Aesthetics: Can be unaesthetic andinelegant, especially if thereis a need to maintain a lot ofinformation.

Nothing need be perceivable,which gives more freedom tothe designer and can lead tobetter aesthetics.


The Difference between Internal and External Memoryinternal memory external memory

• the mental model of the user about the external world is always incomplete

• all necessary information which is not in the internal memory must be provided by the environment (the “external memory”)


The Concept of Natural Mappings

• Definition [see Norman, D., 1988, p. 75ff]:

– A design solution based on a natural mappings reduces the need for additional explanatory information in memory!

– Natural mappings guarantee a minimum number of cognitive transformation steps.

– If a design depends upon labels, it may be faulty. Labels are important and often necessary, but the appropriate use of natural mappings can minimize the need for them. Wherever labels seem necessary, consider another design!


Design of Light Switch Panels (1)• Problem:

– no direct mapping between switches and corresponding lamps


Design of Light Switch Panels (2)


Corrective Design (1)• Problem:

– sliding door can damage the open petrol flap


Corrective Design (2)

• Solution:– extra bar to

lock the sliding door


Design of Door Handles


Design of Shower Faucets• Natural mapping:

– hot water left sideor RED

– cold water right sideor BLUE

• Un-natural mapping:– something else

(see figure)


Natural Mapping (1)


Natural Mapping (2)


Double Design

• Water-tap with– normal screw caps

• plus– infrared sensor for

automatic opening


physical operation

feedback control of action

goal-, subgoal-setting

mental operation

task(s)

planning of execution selection of means

the complete action cycle

synchronisation in time

synchronisation in space


The most important design principle

• Perception Space– The physical space where

the user’s attention is.

• Action Space– The physical space where

the user acts in.

• Design Principle:– perception space and action

space must coincide!


Design of Stove Controls (1)


Design of Stove Controls (2)


Interactive Directness: the desktop example

Pull down menus

Pull down menus

Toolbar


action space

perception space


Head-up Displays in Cars

• More information and less distractionInformation on the state of the road, on the speed of the vehicle in front (supplied by the intelligent cruise control), on obstacles lying around the next bend in the road identified by the remote detection system, or direction arrows sent by the driver guidance system... drivers will be receiving more and more information from "intelligent" vehicle systems. Although the information is intended to enhance safe driving, there is a danger that an abundance of information may produce the opposite effect if driver glance-away time has to increase in order to apprehend the data.


Electronic Performance Support System

• Food processing plant worker with a first-generation prototype wearable computer.

• Possible applications include support for quality control data collection or assistance with environmental auditing.

• This system gives its users the information the users need to perform a task as they actually perform the task.


Airline Applications

• This remarkable ultra-lightweight computer, worn as a belt, delivers maximum information to users with a minimum of work.

• Designed for individuals who demand mobility, this computer offers voice control and heads up display for complete, hands-free operation.

• Users can enter or retrieve information while going about their jobs, instead of constantly returning to the shop area to check a stationary computer, or stopping work to punch keys.


Interlacing display and manipulation spaces

• Exercise-4:– Design a user interface for a computer system

with some of the following components:• input devices: joystick, graphic tablet with pen,

keyboard, mouse, video camera, touch screen

• ouput devices: monitor, video projector

• other components: semitransparent mirrors


Two design principles for natural user interfaces (NUIs):

No technical equipment inside to body space of the user!

2. design principle

Perception space and action space must coincide!

1. design principle


Architecture of a Natural User Interface (NUI)

Working Area

Communication & Working Area

Paper document

Electronic documents

Tognazzini B: Tog on Software Design. (1996).

Wellner P, Mackay W, Gold R: Computer-Augmented Environments: Back to the Real World. (1993)Fitzmaurice G, Ishii H, Buxton W: Bricks: Laying the Foundations for Graspable User Interfaces. (1995)


The Virtual Workbench

The KOSIMA projectat the TU Aachen


virtual player

real chipvirtual chips

overhead projector

video camera

NEW button

NUI (1): The Digital Playing Desk


0

50

100

150

200

250

300

350

400

450

500

Cel

l Me

an f

or

time

of

use

r (s

)

Cell Line Chart for "playing time" Grouping Variable(s): Interface type Error Bars: ± 1 Standard Deviation(s)

CI MI TI DPDP<.001P<.01P<.001

P<.001P<.001

P<.001

Digital Playing Desk: Playing time per game


Digital Playing Desk: winning chance per dialog technique

computer win

remis

user win Cell Line Chart for "winning chance" Grouping Variable(s): Interface type Error Bars: ± 1 Standard Deviation(s)

CI MI TI DPDP<.001P<.080P<.020

P<.802P<.001

P<.007


ProjectionCamera

Gesture Database

NUI (2): a team oriented planning tool


NUI (2): The Build-It System


Section of thetop-view projection“the machine depot”

Picking the object out of the depot

Moving the objectinto the plant

Build-It System: the interaction handler


BUILD-IT: an integrative design tool

• design team with different domain knowledge

• unconstrained social interaction

• integration of form and content

• intuitive interaction style


Actual research goals...

• hand-written input• speech input• two-handed interaction

• new methods and concepts for integrative design

Documents

User-Centred Design: Design Principles (lecture-4)