User interface design principles

This is the basics to think about when designing a GUI, a website, any software with a user interface. See also the very good book “The Design of Everyday Things” by Donald A. Norman, ISBN 0-262-64037-6. I’m not an expert on UI design, so if you can help out please do by adding comments at the foot of the page.

Fundamental principles:

• Consistency is next to godliness
• Simpler is better
• Visible complexity is bad
• Smaller equals easier to us

How humans interact with a system

• Form the goal and the intention
• Specify and execute the action
• Perceive and interpret the system state
• Semantically evaluating the interaction outcome.

Assist the user

• Make the system state explicit: The inner workings of software are hidden from end users who have to figure out the internal state from only a few hints.
• Users act in cycles of action and evaluation.
• Encourage exploration with short response times and unlimited Undo
• Provide end-users with the sense of control.

Minimizing the load on users

• Reduce memory and cognitive load
• Allow a work session to be easily interrupted and resumed without any loss of work (web session timeout for ex making sure all info is on the url)
• Preserve consistencies

Two strategies for displaying data: High density and Low density

High-density

• Tabular arrangement: spreadsheet style
• Hierarchical organization: tree-like hierarchy as in file system graphic representation
• Graph: Data is represented graphically, like a chart or a diagram.

Low-density

• Step-by-step interaction: Wizard style interface
• Details on demand: Some optional data can be shown on user request. Use with care because users feel uncomfortable with a GUI that changes its appearance too much.
• Disable/minimize irrelevant information. There are many ways to minimize data; for example, shading it.