7.2 Usability
Essential idea:
Usability is about how easy it is to use a product or system.
Nature and Aims of Design
Nature of Design
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 utilize appropriate testing and trialling strategies must be used to determine these aspects. (1.5, 1.16, 1.18)
Aims
Aim 3: Designers must consider the limits of population stereotypes. Through recognizing these limits, the designers can critically assess the appropriateness of their product in relation to those who will use it.
Guidance
As DP Design Technology student you should:
Usability objectives
Enhanced usability
Characteristics of good user-product interfaces
Population stereotypes
Guidance:
Usability objectives include usefulness, effectiveness, learnability, attitude (likeability)
Benefits of enhanced usability include product acceptance, user experience, productivity, user error, training and support
Characteristics of good user-product interfaces include simplicity, ease of use, intuitive logic and organization, low memory burden, visibility, feedback, affordance, mapping and constraints.
Advantages and disadvantages of using population stereotypes for designers and users
Concepts and Principles
Usability Objectives
Usability is the extent to which a product can be used by specified users to achieve specified goals effectively
source: ISO
Usefulness
The product enables the user to achieve their goals
Effectiveness (ease of use)
The product is easy and efficient to use; Users can use it easily and with few or no errors
Learnability
The system for operating the product is easy to learn, and users can can understand how to use it after a reasonable amount of training; Infrequent users are able to easily relearn the system
Attitude (likeability)
The users' perceptions, feelings, and opinions of the product are positive
In your IA, consider the usability of your design and involve the user in evaluating how well the prototype meets their needs. You can do this in Criterion Bii by using user feedback to further conceptual models, and in Criterion Dii when testing and evaluating the success of the solution
Benefits of Enhanced Usability
Product Acceptance
A product will perform according to its specifications. In short, it does what it says it will do.
Example: The iPod, though technically inferior to it competitors, gained acceptance because of its usability and consideration of the whole user experience.
User Experience
These are the responses and perceptions of the users as they use a product or service. These could be visual, tactile, or audible feedback to the user - the "clicking" of keys as you type on a phone experience; or the way a user signs up or signs into a website.
Productivity
Designing products that allow the user to be efficient with their time and resources. This creates a more pleasant experience for the user.
Example: 3D printers allow designers to test and prototype quickly and accurately.
Training and Support
Products that have intuitive interfaces require less training and support to use. This can reduce training costs for manufacturers and increase the quality of the user experience.
Example: Nest thermostats are well known for their intuitive user interfaces that easily can clearly communicate the function and status.
User Errors
Simpler interfaces and controls reduce or eliminate user errors. Consequently, using the product or system is easier, safer, and more reliable.
Example: The ClearRX prescription bottle has several features to reduce user error: color coded rings to differentiate medicine for different family members, clear labelling with all the information on one side, and prescription instructions in plain English.
Read more about the story behind the design here and here
Characteristics of Good User-Product Interfaces
The point at where a human interacts with a machine or object is called an interface. Depending on the product, these interfaces can be quite simple or incredibly complex.
Good interfaces are intuitive and easy to use. Without a carefully designed interface, a product may not gain acceptance by consumers.
Many of these characteristics are also echoed by designer Dieter Rams and his 10 Principles for Good Design.
The characteristics listed below do not exist separate of each other - they are inter-related and interdependent.
Airplane cockpit controls are necessarily complex because the pilots must be able to check all systems at once. A novice would have a difficult time understanding how to use this system without specialized training.
Compare the cockpit above to the controls on the Braun record player below, designed by Dieter Rams.
Careful attention has been given to the layout and design of the controls to allow virtually any user to understand and intuitively adjust the settings.
Simplicity
A simple design makes the function and use of the design clear to the user. It is intuitive. Only what is needed is displayed and accessible - there are no confusing controls.
The Leica M10 (2017) camera body has a very simple and minimalist layout of controls - allowing the photographer to easily and intuitively make adjustments to ISO, shutter speed, and aperture. This design is based on the historic M4, used by professionals since the 1960s. Compare this layout to that of Canon 70D below:
The Braun ExacTemp digital thermometer has two buttons - a power button and a temperature button. The screen displays the battery status and the temperature.
Ease of Use
A design should be easy to use and not have any unnecessary features.
"Feature creep," the adding of features to a design regardless of whether they are needed are not, is one way to make a design less easy to use. For designers, this can be a challenge - the easiest way to innovate is to add a feature or function. However, designers need to consider what is essential to meeting the user's needs and accomplishing the task.
Multitools are hand-held tools that combine a number of features into a single tool. Their product category is defined by the fact that they have multiple features, and as such can easily become overwhelmed with too many functions. The challenge for designers and manufacturers is to combine the right type and number of features into a design that is easy to use and durable.
The Leatherman Multitool has been developed over many years to be a high-quality tool that contains the "right number of features". The tool is self-contained, made of durable materials, and has no removable parts that can be lost or misplaced.
The Keluin 23, on the other hand, is made from plastic and metal, with less durable construction. The combination of tools is less logical (a light, scale, knife, hammer, tape measure), and contains removable parts that can easily be lost.
The Leatherman, because of its quality and more refined feature set, is considered to be a more durable, easier to use, and refined design.
Remote controls are another object that span the gamut of complex to simple. The universal remote attempts to control all possible functions while providing a very complicated interface. The Apple TV remote on the other hand has just six buttons, while also making use of other technologies (Siri voice recognition, touch surface) to navigate.
Intuitive Logic and Organization
Intuitive product interfaces make sense for the user - they do not require any special training or require much memorization to use.
Depending on the task, the goals of the user, etc., the interface will have a different logic. For example, a customer wanting to troubleshoot a problem with their product will expect the company's website to be organized in a way that makes finding the answer easy, fast, and logical. An engineer for the same company may use a different interface to upload answers, resources, and information for consumers to access. Each user has different needs that require a different logical organization.
A lack of logical organization makes the product and service difficult to use.
Designers can communicate much about the function of a switch by its location and proximity to other elements of the design. The controls for this Dieter Rams designed Braun T45 radio are organized in a logical way. The dials and switches are organized according to related functions - the black knobs along the bottom modify the sound quality (balance, treble, bass, etc.).
Interface designers will often use paper prototypes to the logic and organization of a website or app. They may also present these to clients or users for feedback to further guide and iterate the design process.
Low Memory Burden
Successful designs do not require the user to memorize complex steps or how to use a device.
Products that are challenging to use may require the user to memorize complex steps - usually due to poor organization or over complication.
Compare the example of the EOS 70D and Leica M10 cameras above. The simpler design of the Leica has a lower memory burden on the user because the controls are self-evident and intuitive.
Visibility
Controls should be visible and their function should be clear. The function and purpose of the control should be self-evident and obvious.
"Norman doors" are good anti-examples. These are doors which have handles that indicate the opposite of their function.
Feedback
When using a product or system, humans want to know if their action is has been received and is successful. This is described by Don Norman as the Gulf of Execution and the Gulf of Evaluation.
Clicks of keys on a computer keyboard, or the highlighting of a letter on a smartphone keyboard provide feedback that the key has been pressed. Feedback is usually provided through a sense: sound, touch, taste, or smell.
Other examples include:
The "click" of a lid as it snaps shut on a container
An LED turning on to indicate power is connected
A gear changer on a bicycle clicking loudly and solidly as it changes gears
Grip Shifters by SRAM give a audible and tactile click to indicate that the gear has been changed. A number gauge shows the gear.
Older generation MacBooks had a "breathing LED" to indicate that it was plugged in and charging.
Affordance
Affordances are the properties of an object that suggest how it can be used or what its function is. For a ball, its round shape, bouncability, and plastic material afford it to be tossed and kicked. Compare this with a glass globe - though it is the same shape it does not afford being kicked or rolled across the floor.
The push plates on a door allow it to be pushed; the handles allow it to be pulled.
AKAI MIDI controller uses a variety of switches, sliders, dials, and buttons to create and manipulate sounds. Each type of controller affords a different type of action and corresponding result.
The many tabs, clips, and snaps of the Osprey Hydraulics hydration bladder allows the user to fill it with water and drink from it using the tube.
The pegs of the coat rack afford users the ability to hang clothing and bags from it.
Mapping
Mapping is related to the logical relationship between the product interface and what actually happens. The simplest example is the light switch: pushing the switch up turns on the light, pushing it down turns off the light. The clearer and more consistent the relationship is, the lower the memory burden, the more intuitive the design, and the easier it is for users to use.
The arbitrary placement of the controls do not match the layout of the heating elements. This arrangement makes it more difficult for the user to understand which switch operates which heating element.
Here the layout of the switches match the layout of the heating elements, making the relationship clear between the switch and the heating elements.
Constraints
Constraints limit the way a product can be used. These are usually implemented in order to prevent the user from making an error.
The red dots on the camera body and lens must be aligned in order for the lens to be mounted to the body. It will not fit on any other way.
The asymmetrical design of the various USB male and female ports and connectors only allow them to be connected in one way. This prevents the user from connecting them incorrectly.
The exception is the symmetrical design of the USB C port and plug, which allows it to be connected either way.
Population Stereotypes
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.
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. This is discussed in detail in 1.1a Anthropometrics.
Colors: Colors have very powerful and specific meanings in different cultures.
Learn more about color and perception in different cultures here.
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 needs 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.
Australian lightswitch, in the "on" position.
North American lightswitch in the "off" position
Right-hand drive dashboard.