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Conceptual Understanding: A design team should be “user” driven and frequent contact with potential users is essential. To understand how a product, service or system may be used, the designer must consider the prior knowledge and experience of the users, as well as their typical psychological responses. Evaluation methods that utilise appropriate testing and trialling strategies must be used to determine these aspects.
Usability objectives: The extent to which a product can be used by specified users to achieve specified goals effectively and efficiently, while functioning in a predictable and consistent manner.
Usefulness (Ease of use)
Product enables users to achieve their goals and the tasks that it was designed to carry out and/or wants needs of the user. Once users have learned the design, how quickly can they perform tasks?
Efficiently – fast and with minimum effort
Effectiveness (Efficiency of use)
Quantitatively measured by speed of performance or error rate and is tied to a percentage of users. Use the design completely and accurately
Prevents errors
Users can recover if errors occur.
Learnability (Unambiguous feedback, Clarity of human interface)
User's ability to operate the system to some defined level of competence after some predetermined period of training. Also, refers to ability for infrequent users to relearn the system.
It is the ease at which the user can learn to use a product?
The intuitiveness to use a product, service or system design.
How easy is it for users to accomplish tasks the first time they encounter the design?
Memorable – when the user returns they do not have to re-learn how to use it
Attitude (Like-ability)
User's perceptions, feelings and opinions of the product, usually captured through both written and oral communication.
Satisfaction or likability when the client uses or interacts with the product, service or system design.
How pleasant is it to use the design?
Enhanced usability
Usability is part of the broader term “user experience” and refers to the ease of access and/or use of a product or website. A design is not usable or unusable per se; its features, together with the context of the user (what the user wants to do with it and the user’s environment), determine its level of usability.
Enhanced usability increases:
Product acceptance – The knowledge that a product or service paid for will meet up to its defined specifications. If it says it will do it, it will.
User experience - a person's perceptions and responses that result from the use or anticipated use of a product, system or service, this can modify over time due to changing usage circumstances. A key click on a phone will influence feelings when typing a message which will in turn provide an experience of the phone itself, all part of the user experience. This can lead users to brand loyalty and increased sales for a company.
Productivity - Developing products and services with the user in mind can reduce time wasting or difficult to understand aspects of a product. This can lead to a more efficient output level for the manufacturer and a more pleasant user experience. For example, a stereo system with simple controls (play, pause etc) would be easier to use and produce than a complex sound system, increasing productivity when manufacturing, less parts. Or one click to buy buttons on various websites
Enhanced usability decreased:
User error – With simpler interfaces and controls, user error is reduced or even eliminated. This leads to a better user experience and product acceptance through reduced frustration with products and services.
Training and support – If a product has a more intuitive user interface, a more pleasant user experience and simpler controls, there is less need for training and support to the consumer and so, reduced costs in these fields.
Good user-product interfaces design exhibits the following features:
low user error rate
high levels of user satisfaction
easy to learn-simple uncomplicated, uncluttered interfaces
easy to use-intuitive design, controls appear where anticipated and actions perform as expected
easy to remember functions and operations are performed over time with an ease of repeatability and high level of competence retention.
10 Characteristics of good user-product interfaces: These include: simplicity and ease of use; intuitive logic, organisation and low memory burden; visibility; feedback; affordance; mapping; and constraints.
Characteristic 1, 2: Simplicity and Ease of use - Products with intuitive and easily accessible interfaces are likely to be more popular with consumers (especially more affluent and older consumers).
Characteristic 3, 4, 5: Intuitive logic, organisation and low memory burden- Easy to use intuitive interface design allows new operators to quickly become competent in the basic operations of a product. Poorly designed, less intuitively organised interfaces place a high level of learning through trial and error. They also increase the memory burden placed on consumers who may use the product intermittently and be destined to repeat the learning process over.
Characteristic 6: Visibility- Colour, symbols of controls should be visible and it should be obvious how they work.
Characteristic 7: Feedback- Feedback is the provision of information, for example, an audible tone to a user, as a result of an action. The tone on a telephone touchpad or the click of a key on a computer keyboard provides feedback to indicate that a key has been pressed.
Characteristic 8: Affordance, Affordance is the property of an object that indicates how it can be used. Buttons afford pushing, and knobs afford turning. On a door, handles afford pulling, whereas push plates afford pushing.
Characteristic 9: Mapping - Mapping relates to the correspondence between the layout/space of buttons of the controls and their required action.
Characteristic 10: Constraints- Constraints limit the way that a product can be used.
Limiting the use actions that can be performed to simplify use and prevent error.
There are two types of constraints: physical and psychological.
Physical constraints limit the range of possible actions by redirecting physical motion. The three kinds of physical constraints are paths, axes and barriers.
Barriers absorb or redirect user actions. By doing this, barriers are able to slow, deflect, or cease user actions that are not conducive to a successful experience.
Axes direct user action into rotary motion. This has several benefits, most notably enabling the control to be of expansive or infinite in length, yet able to exist in a small space.
Paths restrict user action to linear or curvilinear motion. This is accomplished most frequently by the use of grooves or channels. Paths are particularly useful in controls where the control variable range is relatively small.
Psychological constraints limit the range of possible actions by leveraging the way people perceive and think. The three kinds of psychological constraints are symbols, conventions and mappings.
Conventions
Symbols
Mappings
Use constraints to minimise errors. Use physical constraints to reduce unintentional inputs and prevent dangerous actions. Use psychological constraints to improve the clarity and intuitiveness of a design.
Consumers can misuse many products due to inappropriate human factors considerations in their design so it is obvious from looking at products how they should be used. Visibility, feedback, mapping, affordance and constraints are vital for intuitive and user-friendly design.
Different populations have different beliefs, understandings, and expectations. Designers must consider their own assumptions and consider how these might impact the safety and usability of a design.
Population stereotypes
Population stereotypes are responses that are found to be widespread in a user population.
Assumptions and associations are made by the population of a particular culture regarding how equipment and products operate.
It is a concept relating to cultural expectations. It is the manner in which most people in the population expect something to be done. You might think of it as your intuition or your innate functional understanding of something.
Expectations that are found to be widespread in a population are known as conventions or stereotypes. E.g. USA vs. Europe vs Asia. Other examples includes the direction of handles to open and close and also the way switches turn on or off (e.g. with switches in houses and electric car window switch.
Do Android and Iphone users swipe photos in the same direction?
Anthropometric stereotypes: Different population groups differ physically in height, weight, etc. When using anthropometric data designers should carefully consider how accurately the data represents the target user group.
Culture: Different cultures will interpret forms, signs, and signifiers in different ways. In some cases, things may have always been done that way in a culture, and so the designers need to consider this when designing a product or a system. For example, some countries are right-hand drive, while others are lefthand drive. Car designers must consider the layout and organization of controls on the dashboard to reflect the different orientations.
Colours: Colors have very powerful and specific meanings in different cultures.
Advantages of using population stereotypes for designers and users:
For many controls, certain actions we do such as turning, sliding etc will produce the expected result. Many users can operate a product without having to learn how to operate it.
Disadvantages of using population stereotypes for designers and users:
Making use of population stereotypes in the design might sometimes be irrelevant. For example, when a person walks into a room and wants to turn a light switch on, the most common way for Americans is to turn it up, but in other countries, it is the opposite.
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