1. Chapter 2 Foundations of usability
Jeff Offutt
Chapter 2, , Concepts 2-5

2. Users anthropomorphize software
Fundamental Concept 2
Users anthropomorphize software
by expecting it to behave as if it is human
We name our tools
We curse at our home assistants
We expect software to be considerate, thoughtful, and rational
27-Apr-19
© Offutt

3. Knowledge in the world and knowledge in the head
Fundamental Concept 3
Users look for knowledge both in their heads and in the world
Some knowledge that may not be in your head
Write down the names of your country’s states or provinces
Whose face is on a $20 bill? $50?
Giving directions is much harder than walking to it
We merge knowledge in our heads with knowledge in the world
We often do not need to be precise
Good UIs constrain our use with syntax—legos, electronic connections, radio buttons
27-Apr-19
© Offutt

4. Information In the Head Information In the World
Information that we memorize
Our own name
Our address
World
Information that we see or look up
Time
Courses offered next semester
We often move information from one place to another
Our class schedule
The room number for our class
27-Apr-19
© Offutt

5. Precision is Not Needed
People are not good at being precise
The one dollar coin was almost the same size as a quarter—The US made this mistake twice in my life!
Remembering 10-digit phone numbers is hard … so my phone has a contact list and voice activation
The French & Indian war occurred about 20 years before the US revolutionary war … but which year?
We learn to be precise in our field only after years of learning and practice
A good UI must not require precision
But should help the user find precision when required
27-Apr-19
© Offutt

6. Syntactic Constraints
Spelling is hard … but made easier by patterns
What consonants can precede an “h” ?
“ch”, “gh”, “ph”, “rh”, “sh”, “th”, “wh”
Singers, musicians, dancers and martial artists don’t memorize so much as recreate based on patterns that “make sense”
The syntax of a UI must make syntactic constraints clear
In PPTX, if I highlight text, lots of actions are immediately enabled
27-Apr-19
© Offutt

7. Visibility, mapping, and functions
Fundamental Concept 4
Controls must be visible, the features they control must be obvious (mapping), and their effect must be clear (functions)
Invisible controls slow down learning
Unclear mappings slow down learning and increase errors
This is hard because designers don’t get confused
But users do
27-Apr-19
© Offutt

8. Mapping Syntax to Semantics
This arrangement has a natural mapping … fewer mistakes !
How can we remember which control maps to which burner ?
Mistakes are encouraged
27-Apr-19
© Offutt

9. Design usable defaults
Fundamental Concept 5
Most users never change the defaults, even if another option would improve usability
Users assume designers considered defaults carefully with their best interests in mind
Sometimes
Other time defaults are essentially random
And sometimes they are for the company’s benefits
Social media make more money from public settings
We can’t choose good defaults until we understand the users
Designers are NOT typical users
27-Apr-19
© Offutt

10. Foundations of usability
5 measurable criteria
Users anthropomorphize software
Knowledge in the world & in the head
Visibility, mapping, and functions
Defaults
27-Apr-19
© Offutt