chapter3

= = toc

=Principles and Practice=

There are four key concerns of a good design: >
 * **//Accessibility//**: concerned with **removing all the barriers** that would prevent some people from using the system at all**.**
 * **//Usability//**//:// refers to the **quality of interaction** in terms of parameters such as time taken to perform the tasks, number of errors made, the time it took to become a competent user.
 * **//Acceptability//:** Whether or not the design fullfils its purpose completely, it will also take in to account the **personal preferences** of the user which may effect his or her ability to accept the new design to be used for its intended purpose.
 * **//Engagement//**: concerned with providing users with a great, exciting, and interesting **experience**.

Accessibility
People can be excluded from using an interactive system for a number of reasons:
 * //Physically//: people can be excluded because of inappropriate placement of the equipment. For example, something can be placed too high or too low for a person to reach with ease. Also, it may be because the output and the input device make excessive demands on their abilities, for instance it will be hard for a person with arthritis to use a joy stick.
 * //Conceptually//: people may be excluded because of their inability to understand complex instructions or demands which will disable them from forming a clear mental model of the system.
 * //Economically//: people may be excluded simply because they cannot afford the technology.
 * //Cultural Exclusion//: Using an American metaphor or slang words would exclude those who are not familiar with the game/ language.
 * //Social Exclusion//: It can occur if the equipment is not available at the appropriate time and place or if people are not members of a particular group: For instance, our course wikispace is not assessable for anyone who if not enrolled in the class.

Overcoming these barriers is the key to a good design. Two approaches for designing for accessibility: >
 * **Design for All (Universal Design):** refers to going beyond a particular design and applies to all design endeavors.
 * **Inclusive design** is based on for premises:
 * Varying ability: Not do we differ physically and mentally from others but we ourselves change in such respects overtime.
 * If the design works well for people with disabilities, it works well for everyone.
 * Personal user experience and usability are effected by design constraints and choices.

Principles of Universal Design
>
 * //Equitable//: The design does not disadvantage or stigmatize any group of users.
 * //Flexible//: The design accommodates a wide range of individual preferences and abilities.
 * //Simple//: Use of the design is easy to understand regardless of the users knowledge, skills and concentrations level.
 * //Perceptible//: The design effectively communicates necessary information to the users regardless of the surrounding conditions and sensory abilities of the user.
 * //Tolerant//:The design should have minimal consequences for accidental or unintended actions.
 * //Effortless//: The design can be used with comfort and minimum fatigue.
 * //Just Right size and Space//: Appropriate space and size is provided for each and use regardless of users body size and mobility.

Decision Tree
How to decide whether to design for all or just a selected group? >
 * Fixed/changing - is difference innate and immutable, or learned?
 * Common/rare - is difference a reasonably common occurrence?
 * Cheap/Expensive - what is the cost of accommodation?

Usability
Usability refers to a design which is easy to use, easy to learn, and which provides a good attitude to people. A system with a high degree of usability will have the following characteristics:
 * Its **efficiency**will enable people to do things using an appropriate amount of effort:
 * It will be **effective** since it would contain the appropriate functions and information content, organized in an appropriate manner.
 * It will be **easy to learn** and remember how to do things.
 * It will be **safe** to operate in a variety of contexts in which it will be used.
 * It will have high **utility** as it will get the job done that people want it to do.

Achieving usability requires a designer to consider a human centered approach to designed to adopt the star life cycle. >
 * //Early focus on users and tasks//: In order to complete the intended design, the designer must understand who the users would be and make them a part of the design team by consulting their opinions needs and wants.
 * //Empirical Measurement//:
 * Firstly, the reaction of intended users to manuals and printed scenarios should be observed and measured.
 * Secondly, their reaction to simulations and prototypes should also be observed, recorded and measured.
 * //Iterative Design//: a cycle of design, where it should be tested and measured and redesign, with the cycle being repeated as often as necessary. When problems are found in user testing, they must be fixed.
 * //Co-evolution and mutual dependence//: All usability factors must evolve together and the responsibility for all aspects of usability should be under one control.

Usability is concerned with achieving a balance in the PACT elements. Observe figue on page 57. Usability requires that the two gulfs be bridged. Gulf of execution is concerned with translating goals into actions. The gulf of evaluation is concerned with deciding whether the actions moved the user any closer to his or her goals. Observe figure on page 59.

Acceptability
It is about fitting technologies into people’s lives. The difference between acceptability and usability is that acceptability can only be understood in the context of use by the users themselves when usability can be evaluated in a lab.

Factors influencing acceptability:
 * //Political//: Trust - Do people trust it?
 * //Organizational Issues//: In many organizations, technologies are introduced mainly for economic reasons regardless of the opinion of the people who would actually use them.
 * //Convenience//: Designs that are awkward or that force people to do things may not be unacceptable.
 * //Cultural and Social Habits//: It is concerned with how people like to live, for instance they dont like to be disturbed so SPAM email is considered undesired and unwelcomed in a persons inbox.
 * //Usefulness//: It concerns usefulness in context. For instance, diary on a cell phone is useful but not in everyday life
 * //Economic//: Price, changes in business model - how business works and how they make money.

Engagement
Engagement is concerned with all the qualities of an interactive experience that makes it memorable, satisfying, enjoyable and rewarding, or whether its a sense of immersion. A challenge or a fascination unfolding. Engagment is about ensuring that the interaction flows by the creation of a bond.

Functions of Engagment:
 * //Identity//: A sense of identity and expression of the self, cohesion.
 * //Adaptivity//: is to do with change and personalization with changing levels of difficulty, pace and movement.
 * //Narrative//: is to do with telling something in a good way, with convincing characters and plot whether its a corporate video or a fiction story.
 * //Immersion//: Being completly involved in something
 * //Flow//: Smooth movement, the gradual change from one state to another.

1. **Visibility**- Try to ensure that things are visible so that people can see what functions are available and what the system is currently doing. This is an important part of the psychological principle that it is easier to recognize things than to have to recall them 2. **Consistency**- Be consistent in the use of design features and be consistent with similar systems and standard way of working. 3. **Familiarity**- Use language and symbols that the intended audience will be familiar with. 4. **Affordance**- Design things so it is clear what they are for; for example make buttons look like they are buttons so people will press them 5. **Navigation**- Provide support to enable people to move around the parts of the system: maps, directional signs etc. 6. **Control**- Make it clear who or what is in control and allow people to take control. 7. **Feedback**- Rapidly feed back information from the system to people so that they know what effect their actions have had. Constant and consistent feedback will enhance the feeling of control. 8. **Recovery**- Enable recovery from actions, particularly mistakes and errors, quickly and effectively. 9. **Constraints**- Provide constraints so that people do not try to do things that are inappropriate…dangerous operations 10. **Flexibility**- Allow multiple ways of doing things so as to accommodate users with different levels of experience and interest in the systems. 11. **Style**- Designs should be stylish and attractive. 12. **Conviviality**- Interactive systems should be polite, friendly, and generally pleasant.
 * //__Design Principles:__//**