Design of Everyday Things Don Norman on Design & HCI.

Design of Everyday Things

Don Norman on Design & HCI

Summary

Darn these hooves!I hit the wrong switch again!Who designs these instrumentPanels, raccoon?!

Don Norman

Professor at Northwestern and Principal of Nielsen Norman group

Previously Professor at UCSD, senior positions at Apple & HP

ACM/CHI Lifetime Achievement Award

Prolific author http://www.jnd.org/

Discussion

What did you take away from DOET book so far?

Here are some

Affordances are important Minimize the gulf of interpretation and

gulf of execution Use natural mappings Make state visible Use a conceptual model that makes

sense Provide feedback

Daily Challenges

How many of you can use all the functionality in yourVCRDigital watchCopy machineStereo systemPlumbing fixtures

Hall of Shame Example

Leitz slide projectorTo move forward, short pressTo move backward, long press

What happens when you get frustrated?

Fun Examples

Phones

How do you- transfer a call- change volume- store a number- ...

Changing Ringer Volume

Press “Program” Press “6” Set volume

Low - Press “1”Medium - Press “2”High - Press “3”

Press “Program”

Much better…

Important Concepts

Affordances Visibility Conceptual models Mapping Feedback Constraints

Affordances

Perceived and actual properties of an object that determine how it could be usedChair is for sittingButton is for pushingDoor handle is for ….Scroll arrow is for …Icon is for …

Door Opening Affordances

1 2 3 4 5

6 7

Which doors are easy to open?

Which doors are hard to open?

Why?

Affordances in interfaces

Interfaces are virtual and do not have ‘real’ affordances like physical objects

Interfaces have ‘perceived’ affordances Learned conventions of arbitrary mappings

between action and effect at the interface Some mappings are better than others

Mantra

Complex things may need explanation, but simple things should notIf a simple thing requires instructions,

it is likely a failed design

Designing for People

Norman’s 2 main principlesProvide a good conceptual modelMake things visible

• Affordances is part of this

Conceptual Models

People build their own systems of how things workExample - thermostat

Designer can help user foster an appropriate conceptual modelAppearance, instructions, behavior...

Conceptual Models

Mental models are not always right Two Classes:

Functional model• Stimulus - response• “Press the accelerator once, then turn the key”• At surface or superficial level

Structural model• Deeper sense of why it happens, not just what

happens• “Press the accelerator to engage the automatic

choke on a carburetor”

Visibility

When functionality is hidden, problems in use occurOccurs when number of functions is

greater than number of controls When capabilities are visible, it does

not require memory of how to useRecognition over Recallin the world vs. in the head

Simple Example

Bathroom faucetsTwo functions

• Hot/cold• Flow

Bathroom Faucets 1

Can you figureout how to useit?

Are two functionsclear and independent?

Bathroom Faucets 2

Can you figureout how to useit?

Are two functionsclear and independent?

Bathroom Faucets 3

Can you figureout how to useit?

Are two functionsclear and independent?

My parent’s microwave

5:45

My microwave

About that VCR…

That old joke - “how many of you have a VCR that is blinking 12:00?” :-)

Still true today :-(

Which is Faster for Setting Time?

Two Important Principles

Mapping Feedback

Mapping

Relationship between control and action/result in the world

Take advantage of physical analogies or cultural understandingsGood:

• Car, various driving controls• Mercedes Benz seat adjustment example

Bad• Car stereo - Knob for front/back speakers

Which is better?

or

Mapping Example: Euros

Size::value

Mapping Example: Stove

Which controls which?

Why not this?

Yikes!

Why Not Design Better

Stove

Speakers

Physical, monetary,convenience, etc.,constraints dictateotherwise

Feedback

Sending information back to the user about what has been done

Includes sound, highlighting, animation and combinations of these

e.g. when screen button clicked on provides sound or red highlight feedback:

“ccclichhk”

Example

ScissorsAffordances - Insert somethinginto holes

Constraints - Bigger hole forseveral fingers, small for thumb

Mapping - How to insert fingersinto holes suggested by visibleappearance

Conceptual model - Suggested byhow parts fit together and move

Execution-Evaluation cycle

Norman (DOET, p. 46)

UserGoals

PhysicalSystem

Gulfof

Execution

Gulfof

Evaluation

Goals, Execution, Evaluation

Physical System

GoalsWhat we

want to happen

ExecutionWhat we

do to the world

EvaluationComparing what happened

with what we wanted to happen

(Gulf of Execution) (Gulf of Evaluation)

Execution

GoalsWhat we

want to happen

An intention to actso as to achieve the goal

The actual sequence of actionsthat we plan to do

The physical execution of that action sequence

Physical System

Evaluation

GoalsWhat we

want to happen

Evaluation of the interpretationswith what we expected to happen

Interpreting the perception accordingto our expectations

Perceiving the stateof the world

Physical System

Seven Stages - All Together

GoalsWhat we

want to happen

Evaluation of the interpretationswith what we expected to happen

Interpreting the perception accordingto our expectations

Perceiving the stateof the world

An intention to actso as to achieve the goal

The actual sequence of actionsthat we plan to do

The physical execution of that action sequence

Physical System

Implications – Which Gulf does these Address?

Make current state and action alternatives visible Need good conceptual model with consistent system

image Interface should include mappings that reveal

relationships between stages User should receive continuous feedback Provide affordances

Goal: Minimize Gulfs

Gulf of Execution Conceptual model Affordances Natural mappings

Gulf of Evaluation Make state visible Feedback

Try and Try Again

Norman thinks that it often takes 5 or 6 tries to get something “right”

Simply may not have that luxury in a competitive business environment