Natural design involves using natural signals which do not require conscious interpretation in order to use them.
Principles of good design involve making the state of the device visible, giving the user a good conceptual model, using good mappings, and providing appropriate feedback.
Knowledge in the world is accessible; great precision is usually not required for successful completion of tasks; physical properties of objects constrain possible actions; and, knowledge in the mind is ephemeral.
Affordances suggest a possible range of possible actions; constraints limit the range of alternative actions.
"When simple things need pictures, labels, or instructions, the design has failed."
Once a satisfactory product has been designed, leave it alone; further changes may ruin your design.
Design should:
The human mind is designed to make sense of things. Give a person some clue as to the use of an object, and the mind will try to explain, rationalize, understand, or use the object. Dr. Norman makes the point that well-designed objects are easy to interpret, understand, and use because they contain visible cues for use. Poorly-designed objects are difficult to interpret, understand, and use because they provide false cues, sometimes misleading cues to trap the user and thwart the normal process of interpreting and understanding.
Norman asserts that mistakes are due to poor design principles and claims that designers "make the mistake of not taking error into account." He gives four prescriptions for designers:
Well-designed objects are easy to interpret and understand. They contain visible clues for their operation. Poorly designed objects can be difficult and frustrating to use. They provide no clues � or sometimes, false clues. They trap the user and divert the normal process of interpretation and understanding.
A device is easy to use when there is visibility to the set of possible actions, where the controls and displays exploit natural mappings. The principles are simple but rarely incorporated into design. Good design takes care, planning, thought. It takes conscious attention to the needs of the user.
Poor design predominates!!
There are psychological principles that can be followed to make these things understandable and usable.
A good conceptual model allows to predict the effect of our actions.
Without a good conceptual model we do operations as we were told to do them; we cant fully appreciate why, what effects to expect, or what to do if things go wrong.
In order to start designing one should:
- Form a conceptual model of the device and mentally stimulate its operation
- Other clues to how things work come from their visible structure � in particular from affordances, constraints, and mappings.
Example:
Scissors:
- The holes are affordances.
- The size of holes provide constraints to limit the possible fingers: the big hole suggests several fingers, the small hole only one.
- The mapping between holes and fingers � the set of possible operations � is suggested and constrained by the holes.
You can figure out scissors because their operating parts are visible and the implications clear. The conceptual model is made obvious, and there is effective use of affordances and constraints.
The correct parts of an object must be visible and convey the correct message.
Natural Signals allow to be naturally interpreted, without any need to be conscious of them.
The use of natural signals leads to natural design.
Visibility indicates the mapping between intended actions and actual operations.
Visibility acts as a good reminder of what can be done and allows the control to specify how the action is to be performed.
Causality
False causality
Something that happens right after an action appears to be caused by that action.
e.g. Touch a computer terminal just when it fails, and you are apt to believe that you caused the failure, even though the failure and your actions were related only by coincidence. Such false causality is the basis for much superstition.
Lack of clues.
- There must be a visible outcome for each operation. The user should know whether the action he / she performed worked.
- When an action has no apparent result, you may conclude that the action was ineffective. So you repeat it.
- It is poor design that allows either kind of false causality to occur.
Affordances
- The perceived and actual properties that determine just how the thing could be possibly used.
- Affordances provide strong clues to the operation of things.
- When affordances are taken advantage of, the user knows what to do just by looking: no picture is required.
- Complex things may require explanation, but simple things should not.
- When simple things need pictures, labels, or instructions, the design has failed.
Mapping is a technical term meaning the relationship between two things.
Natural mapping take advantage of physical analogies and cultural standards, leads to immediate understanding.
Natural choices are visible, closely related to desired outcome and providing immediate feedback.
Feedback - sending back to the user information about what actions has actually been done, what results has been accomplished - is a well-known concept in the science of control and information theory
Tactile Feedback or Auditory Feedback
New designs are pushing hard on the paradox of technology: added functionality generally comes along at the price added complexity, but in expense of feedback. New designed objects are often missing the feedback to the user. The trade-off is cost versus usability.
The Paradox of Technology
Technology offers the potential to make life easier and more enjoyable; each new technology provides increased benefits. At the same time added complexities arise to increase our difficulty and frustration.
The same technology that simplifies life by providing more functions in each device also complicates life by making the device harder to learn, harder to use, the design becomes arbitrary, unnatural and complicated. This is a paradox of technology.
The paradox of technology should never be used as an excuse for poor design.
How do people cope with bad design?? And why should they be concerned about it?
The answer lies in:
- The way the mind works - in the psychology of human thought and cognition
- Information available from the appearance of the objects - in the psychology of everyday things
- Ability of the designer to make the operation clear, project a good image of the operation and to take advantage of other things people might be expected to know.
Here is where the designer's knowledge of the psychology of people coupled with knowledge of how things work becomes crucial.