Some Design Principles

In this section, I will be talking about some design principles for effective user interface design.

We can look at the following aspects:

1. Input Basics :
    Keyboard vs. Mouse vs. Joystick

2. Basics of display design

3. Icons vs. Words and display objects

4. Method structure

5. Support for learning

6. Error recovery

7. Documentation and on-line help

Keyboard Control:


Practice will make a man perfect

If the user needs to pause to recall a command, the speed advantage is gone.

The mouse is the best choice to point to arbitrary objects.

- As long as objects are big enough
- Fitt's law shows that pointing time is:
       - Less than linear with increasing distance

Joysticks

Joysticks are good for simulating
For example, for airplane simulation, joysticks are good.

Joysticks are NOT good as pointing device

Don't focus on Appearance


Don't be too concerned with what the display look like because :-

Information retrieval is more important than display


Make sure that the information for each decision is on the screen which the decision is made

Try to have relevant information simultaneously because :-

- Eye movements are fast as compared to additional screens of information

Good Approaches :


- Key information and control always visible

Icons vs. Words as display objects


The current trend is that we should use nifty icons and not boring words. However, this trend is misguided.

There is something we have been taught to use and process information -- words

Icons are often arbitrary and meaningless as compared to typical words for comparing objects

Method Structure

Users should be able to accomplish tasks using a small number of simple and efficient methods

Every high frequency critical task goal should have a simple method

Similar goals should have similar methods


Support for Learning


Ease of learning and speed of use can go hand in hand

Single biggest contribution to ease of learning : Intuition


Simple and Consistent Methods


- Careful choice of functionality and interface design can result in simple methods for learning

Error Recovery


- User errors are difficult design issues

Hard to predict when error will occur

Documentation and On-line help


Documentation should present all of the components of GOMS model for task

- Most documents present list of operator description

Instead:

- Table of contents should have user goals

References :

http://www.eecs.umich.edu/~soar/Classes/494/talks/User-interfaces.pdf