There are three key principles:
1. You are trying to use
information instead of assumptions.
Assumptions are fast, but often wrong, relating to your personal
experience rather than the users of your design.
Ergonomics is objective, and uses data.
It involves research, measurement and testing.
2. The user is always right - there is no such thing as "human error"
in the sense of 'oh it was his mistake nothing to be done'. Some
designs invite mistakes more than others.
It's up to the design to take account of the way people are, and the
situation they will be in. Human fallibility must be allowed for.
3. The average is no use to you, it
can lead to absurdly low standards as the little joke above shows. Your concern is with the
percentage of people your design is suitable for, and also what the
other more extreme users will experience.
If you're starting out on a design project, here are some ergonomics questions to find answers to...
1. Who will be using the design? It's unlikely to be 'everyone',
or people like you.
Ideally, you would use data such as market research demographics to identify age, sex, and social aspects.
Then among the characteristics you might want to define are:
- Physical size
- Skills like eyesight and coordination
Also cognitive capabilities like:
- Familiarity with similar designs
- Ease of learning
- Familiarity with concepts and metaphors used in the design
All these factors will influence basic aspects of the design, including its scope, complexity, display size etc. etc.
If the users are not well known to you as a group, it may be a good idea to involve some
representatives very early in the process, to make sure that your design does not set off in an
unsuitable direction at the outset.
2. What do its users want to achieve with it?
This is something to think about because it may not be quite obvious. For example the act of using the
design may not form any part of the user's objectives, or it may be secondary.
This might guide you as to what users are
thinking about as they start using the design, and
thus how you can best guide their attention.
For many designs it can be helpful to set a testable criterion for design success, such as a percentage of users who can achieve their objective
within a certain time.
Then it follows that you consider what happens to those people who cannot achieve their objectives, and how serious that is.
|3. What percentiles are appropriate?
This follows from the previous question, and the answer is different for every project. It is best to see it in terms of
a percentage of users from the design, then you can formally consider:
- What happens for excluded users - discomfort, inconvenience, danger etc.
- Do the excluded users expect this (e.g. a very tall person may be used to
being cramped in an economy aircraft seat, but not in a luxury car).
- Can you warn the excluded users.
- Some dimensions may need to be more
generously specified than others.
|4. Where will it be used?
Putting the design in its context can reveal key factors such as
- How much time people have to learn,
- What they are expecting.
- If they will be distracted or under stress (which can decimate the ability to
- If reading instructions is really likely.
- What the users will be wearing.
- Things users may be carrying or holding.
- What happens to it while it is not being used.
- Temperature, humidity, wind, light.
|5. The Golden Rule
||If you were going to pick one golden rule it
would be: Test.