1. Krug Chapter 6 B: Flow in UIs
Jeff Offutt
SWE 205
Software Usability and Design

2. Flow in User Interfaces
If the UI’s manifest model matches the users’ mental model the user can use the software without thinking
By doing what comes naturally
1-Jan-19
© Jeff Offutt

3. It’s easy to make things complicated, it’s hard to make things simple
GUI Flow
Flow: The next thing the interface wants to do is exactly what the user expects
Follow users’ mental model
Users direct the software
Don’t talk with the user
Keep related tools available
Modeless feedback : The user should not have to respond
Interfaces should be invisible, not cool
It’s easy to make things complicated, it’s hard to make things simple
1-Jan-19
© Jeff Offutt

4. Flow is a State of Mind
When in the flow, users have good concentration and are not easily distracted
Syntax interferes with flow
Surprises interrupt flow
Good flow allows users to concentrate on task-semantic knowledge, not syntactic
1-Jan-19
© Jeff Offutt

5. Design for the Probable Provide for the Possible
Make the most likely choices default
Less likely choices can be harder to find
Choices should be based on probability, not logic
Logic : 1 out of a million is possible … if p then s1 else s2
That’s programmer thinking
Probability : Make the 999,999 default, make the 1 hard to find
That’s user thinking!
Default should save changes when I exit
Of course I want to save !
Include a low probability option to discard and exit
1-Jan-19
© Jeff Offutt

6. Making the UI Disappear
Less interaction, not more – what do users need?
Indicate status visually – pictures, not words
Don’t use dialogs to report normal behavior
Provide default behavior and ways to change it
Don’t ask questions, give users choices
1-Jan-19
© Jeff Offutt

7. Help users find their stuff
Daily Summary
Understand the users
Help users find their stuff
Make sure navigation matches their mental model to create flow
Design for the probable; provide for the possible
1-Jan-19
© Jeff Offutt