User interface


In the industrial design field of human-computer interaction, a user interface is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine from the human end, whilst the machine simultaneously feeds back information that aids the operators' decision-making process. Examples of this broad concept of user interfaces include the interactive aspects of computer operating systems, hand tools, heavy machinery operator controls, and process controls. The design considerations applicable when creating user interfaces are related to, or involve such disciplines as, ergonomics and psychology.
Generally, the goal of user interface design is to produce a user interface which makes it easy, efficient, and enjoyable to operate a machine in the way which produces the desired result. This generally means that the operator needs to provide minimal input to achieve the desired output, and also that the machine minimizes undesired outputs to the user.
User interfaces are composed of one or more layers, including a human-machine interface that interfaces machines with physical input hardware such as keyboards, mice, or game pads, and output hardware such as computer monitors, speakers, and printers. A device that implements an HMI is called a human interface device. Other terms for human-machine interfaces are man-machine interface and, when the machine in question is a computer, human-computer interface. Additional UI layers may interact with one or more human senses, including: tactile UI, visual UI, auditory UI, olfactory UI, equilibrial UI, and gustatory UI.
Composite user interfaces are UIs that interact with two or more senses. The most common CUI is a graphical user interface, which is composed of a tactile UI and a visual UI capable of displaying graphics. When sound is added to a GUI, it becomes a multimedia user interface. There are three broad categories of CUI: standard, virtual and augmented. Standard composite user interfaces use standard human interface devices like keyboards, mice, and computer monitors. When the CUI blocks out the real world to create a virtual reality, the CUI is virtual and uses a virtual reality interface. When the CUI does not block out the real world and creates augmented reality, the CUI is augmented and uses an augmented reality interface. When a UI interacts with all human senses, it is called a qualia interface, named after the theory of qualia. CUI may also be classified by how many senses they interact with as either an X-sense virtual reality interface or X-sense augmented reality interface, where X is the number of senses interfaced with. For example, a Smell-O-Vision is a 3-sense Standard CUI with visual display, sound and smells; when virtual reality interfaces interface with smells and touch it is said to be a 4-sense virtual reality interface; and when augmented reality interfaces interface with smells and touch it is said to be a 4-sense augmented reality interface.

Overview

The user interface or human–machine interface is the part of the machine that handles the human–machine interaction. Membrane switches, rubber keypads and touchscreens are examples of the physical part of the Human Machine Interface which we can see and touch.
In complex systems, the human–machine interface is typically computerized. The term human–computer interface refers to this kind of system. In the context of computing, the term typically extends as well to the software dedicated to control the physical elements used for human-computer interaction.
The engineering of human–machine interfaces is enhanced by considering ergonomics. The corresponding disciplines are human factors engineering and usability engineering, which is part of systems engineering.
Tools used for incorporating human factors in the interface design are developed based on knowledge of computer science, such as computer graphics, operating systems, programming languages. Nowadays, we use the expression graphical user interface for human–machine interface on computers, as nearly all of them are now using graphics.
Multimodal interfaces allow users to interact using more than one modality of user input.

Terminology

There is a difference between a user interface and an operator interface or a human–machine interface.
In science fiction, HMI is sometimes used to refer to what is better described as a direct neural interface. However, this latter usage is seeing increasing application in the real-life use of prostheses—the artificial extension that replaces a missing body part.
In some circumstances, computers might observe the user and react according to their actions without specific commands. A means of tracking parts of the body is required, and sensors noting the position of the head, direction of gaze and so on have been used experimentally. This is particularly relevant to immersive interfaces.

History

The history of user interfaces can be divided into the following phases according to the dominant type of user interface:

1945–1968: Batch interface

In the batch era, computing power was extremely scarce and expensive. User interfaces were rudimentary. Users had to accommodate computers rather than the other way around; user interfaces were considered overhead, and software was designed to keep the processor at maximum utilization with as little overhead as possible.
The input side of the user interfaces for batch machines was mainly punched cards or equivalent media like paper tape. The output side added line printers to these media. With the limited exception of the system operator's console, human beings did not interact with batch machines in real time at all.
Submitting a job to a batch machine involved, first, preparing a deck of punched cards describing a program and a dataset. Punching the program cards wasn't done on the computer itself, but on keypunches, specialized typewriter-like machines that were notoriously bulky, unforgiving, and prone to mechanical failure. The software interface was similarly unforgiving, with very strict syntaxes meant to be parsed by the smallest possible compilers and interpreters.
Once the cards were punched, one would drop them in a job queue and wait. Eventually, operators would feed the deck to the computer, perhaps mounting magnetic tapes to supply another dataset or helper software. The job would generate a printout, containing final results or an abort notice with an attached error log. Successful runs might also write a result on magnetic tape or generate some data cards to be used in a later computation.
The turnaround time for a single job often spanned entire days. If one were very lucky, it might be hours; there was no real-time response. But there were worse fates than the card queue; some computers required an even more tedious and error-prone process of toggling in programs in binary code using console switches. The very earliest machines had to be partly rewired to incorporate program logic into themselves, using devices known as plugboards.
Early batch systems gave the currently running job the entire computer; program decks and tapes had to include what we would now think of as operating system code to talk to I/O devices and do whatever other housekeeping was needed. Midway through the batch period, after 1957, various groups began to experiment with so-called “load-and-go” systems. These used a monitor program which was always resident on the computer. Programs could call the monitor for services. Another function of the monitor was to do better error checking on submitted jobs, catching errors earlier and more intelligently and generating more useful feedback to the users. Thus, monitors represented the first step towards both operating systems and explicitly designed user interfaces.

1969–present: Command-line user interface

Command-line interfaces evolved from batch monitors connected to the system console. Their interaction model was a series of request-response transactions, with requests expressed as textual commands in a specialized vocabulary. Latency was far lower than for batch systems, dropping from days or hours to seconds. Accordingly, command-line systems allowed the user to change his or her mind about later stages of the transaction in response to real-time or near-real-time feedback on earlier results. Software could be exploratory and interactive in ways not possible before. But these interfaces still placed a relatively heavy mnemonic load on the user, requiring a serious investment of effort and learning time to master.
The earliest command-line systems combined teleprinters with computers, adapting a mature technology that had proven effective for mediating the transfer of information over wires between human beings. Teleprinters had originally been invented as devices for automatic telegraph transmission and reception; they had a history going back to 1902 and had already become well-established in newsrooms and elsewhere by 1920. In reusing them, economy was certainly a consideration, but psychology and the Rule of Least Surprise mattered as well; teleprinters provided a point of interface with the system that was familiar to many engineers and users.
The widespread adoption of video-display terminals in the mid-1970s ushered in the second phase of command-line systems. These cut latency further, because characters could be thrown on the phosphor dots of a screen more quickly than a printer head or carriage can move. They helped quell conservative resistance to interactive programming by cutting ink and paper consumables out of the cost picture, and were to the first TV generation of the late 1950s and 60s even more iconic and comfortable than teleprinters had been to the computer pioneers of the 1940s.
Just as importantly, the existence of an accessible screen — a two-dimensional display of text that could be rapidly and reversibly modified — made it economical for software designers to deploy interfaces that could be described as visual rather than textual. The pioneering applications of this kind were computer games and text editors; close descendants of some of the earliest specimens, such as rogue, and vi, are still a live part of Unix tradition.

1985: SAA User Interface or Text-Based User Interface

In 1985, with the beginning of Microsoft Windows and other graphical user interfaces, IBM created what is called the Systems Application Architecture standard which include the Common User Access derivative. CUA successfully created what we know and use today in Windows, and most of the more recent DOS or Windows Console Applications will use that standard as well.
This defined that a pulldown menu system should be at the top of the screen, status bar at the bottom, shortcut keys should stay the same for all common functionality. This greatly helped the speed at which users could learn an application so it caught on quick and became an industry standard.

1968–present: Graphical User Interface

Primary methods used in the interface design include prototyping and simulation.
Typical human–machine interface design consists of the following stages: interaction specification, interface software specification and prototyping:
All great interfaces share eight qualities or characteristics:
  1. Clarity: The interface avoids ambiguity by making everything clear through language, flow, hierarchy and metaphors for visual elements.
  2. Concision: It's easy to make the interface clear by over-clarifying and labeling everything, but this leads to interface bloat, where there is just too much stuff on the screen at the same time. If too many things are on the screen, finding what you're looking for is difficult, and so the interface becomes tedious to use. The real challenge in making a great interface is to make it concise and clear at the same time.
  3. Familiarity: Even if someone uses an interface for the first time, certain elements can still be familiar. Real-life metaphors can be used to communicate meaning.
  4. Responsiveness: A good interface should not feel sluggish. This means that the interface should provide good feedback to the user about what's happening and whether the user's input is being successfully processed.
  5. Consistency: Keeping your interface consistent across your application is important because it allows users to recognize usage patterns.
  6. Aesthetics: While you don't need to make an interface attractive for it to do its job, making something look good will make the time your users spend using your application more enjoyable; and happier users can only be a good thing.
  7. Efficiency: Time is money, and a great interface should make the user more productive through shortcuts and good design.
  8. Forgiveness: A good interface should not punish users for their mistakes but should instead provide the means to remedy them.

    Principle of least astonishment

The principle of least astonishment is a general principle in the design of all kinds of interfaces. It is based on the idea that human beings can only pay full attention to one thing at one time, leading to the conclusion that novelty should be minimized.

Principle of habit formation

If an interface is used persistently, the user will unavoidably develop habits for using the interface. The designer's role can thus be characterized as ensuring the user forms good habits. If the designer is experienced with other interfaces, they will similarly develop habits, and often make unconscious assumptions regarding how the user will interact with the interface.

A model of design criteria: User Experience Honeycomb

Peter Morville of Google designed the User Experience Honeycomb framework in 2004 when leading operations in user interface design. The framework was created to guide user interface design. It would act as a guideline for many web development students for a decade.
  1. Usable: Is the design of the system easy and simple to use? The application should feel familiar, and it should be easy to use.
  2. Useful: Does the application fulfill a need? A business’s product or service needs to be useful.
  3. Desirable: Is the design of the application sleek and to the point? The aesthetics of the system should be attractive, and easy to translate.
  4. Findable: Are users able to quickly find the information they're looking for? Information needs to be findable and simple to navigate. A user should never have to hunt for your product or information.
  5. Accessible: Does the application support enlarged text without breaking the framework? An application should be accessible to those with disabilities.
  6. Credible: Does the application exhibit trustworthy security and company details? An application should be transparent, secure, and honest.
  7. Valuable: Does the end-user think it's valuable? If all 6 criteria are met, the end-user will find value and trust in the application.

    Types

  8. Attentive user interfaces manage the user attention deciding when to interrupt the user, the kind of warnings, and the level of detail of the messages presented to the user.
  9. Batch interfaces are non-interactive user interfaces, where the user specifies all the details of the batch job in advance to batch processing, and receives the output when all the processing is done. The computer does not prompt for further input after the processing has started.
  10. Command line interfaces prompt the user to provide input by typing a command string with the computer keyboard and respond by outputting text to the computer monitor. Used by programmers and system administrators, in engineering and scientific environments, and by technically advanced personal computer users.
  11. Conversational interfaces enable users to command the computer with plain text English or voice commands, instead of graphic elements. These interfaces often emulate human-to-human conversations.
  12. Conversational interface agents attempt to personify the computer interface in the form of an animated person, robot, or other character, and present interactions in a conversational form.
  13. Crossing-based interfaces are graphical user interfaces in which the primary task consists in crossing boundaries instead of pointing.
  14. Direct manipulation interface is the name of a general class of user interfaces that allow users to manipulate objects presented to them, using actions that correspond at least loosely to the physical world.
  15. Gesture interfaces are graphical user interfaces which accept input in a form of hand gestures, or mouse gestures sketched with a computer mouse or a stylus.
  16. Graphical user interfaces accept input via devices such as a computer keyboard and mouse and provide articulated graphical output on the computer monitor. There are at least two different principles widely used in GUI design: Object-oriented user interfaces and application-oriented interfaces.
  17. Hardware interfaces are the physical, spatial interfaces found on products in the real world from toasters, to car dashboards, to airplane cockpits. They are generally a mixture of knobs, buttons, sliders, switches, and touchscreens.
  18. provide input to electronic or electro-mechanical devices by passing a finger through reproduced holographic images of what would otherwise be tactile controls of those devices, floating freely in the air, detected by a wave source and without tactile interaction.
  19. Intelligent user interfaces are human-machine interfaces that aim to improve the efficiency, effectiveness, and naturalness of human-machine interaction by representing, reasoning, and acting on models of the user, domain, task, discourse, and media.
  20. Motion tracking interfaces monitor the user's body motions and translate them into commands, currently being developed by Apple.
  21. Multi-screen interfaces, employ multiple displays to provide a more flexible interaction. This is often employed in computer game interaction in both the commercial arcades and more recently the handheld markets.
  22. Natural-language interfaces are used for search engines and on webpages. User types in a question and waits for a response.
  23. Non-command user interfaces, which observe the user to infer their needs and intentions, without requiring that they formulate explicit commands.
  24. Object-oriented user interfaces are based on object-oriented programming metaphors, allowing users to manipulate simulated objects and their properties.
  25. Permission-driven user interfaces show or conceal menu options or functions depending on the user's level of permissions. The system is intended to improve the user experience by removing items that are unavailable to the user. A user who sees functions that are unavailable for use may become frustrated. It also provides an enhancement to security by hiding functional items from unauthorized persons.
  26. Reflexive user interfaces where the users control and redefine the entire system via the user interface alone, for instance to change its command verbs. Typically, this is only possible with very rich graphic user interfaces.
  27. Search interface is how the search box of a site is displayed, as well as the visual representation of the search results.
  28. Tangible user interfaces, which place a greater emphasis on touch and physical environment or its element.
  29. Task-focused interfaces are user interfaces which address the information overload problem of the desktop metaphor by making tasks, not files, the primary unit of interaction.
  30. Text-based user interfaces are user interfaces which interact via text. TUIs include command-line interfaces and text-based WIMP environments.
  31. Touchscreens are displays that accept input by touch of fingers or a stylus. Used in a growing amount of mobile devices and many types of point of sale, industrial processes and machines, self-service machines, etc.
  32. Touch user interface are graphical user interfaces using a touchpad or touchscreen display as a combined input and output device. They supplement or replace other forms of output with haptic feedback methods. Used in computerized simulators, etc.
  33. Voice user interfaces, which accept input and provide output by generating voice prompts. The user input is made by pressing keys or buttons, or responding verbally to the interface.
  34. Web-based user interfaces or web user interfaces that accept input and provide output by generating web pages viewed by the user using a web browser program. Newer implementations utilize PHP, Java, JavaScript, AJAX, Apache Flex,.NET Framework, or similar technologies to provide real-time control in a separate program, eliminating the need to refresh a traditional HTML-based web browser. Administrative web interfaces for web-servers, servers and networked computers are often called control panels.
  35. Zero-input interfaces get inputs from a set of sensors instead of querying the user with input dialogs.
  36. Zooming user interfaces are graphical user interfaces in which information objects are represented at different levels of scale and detail, and where the user can change the scale of the viewed area in order to show more detail.

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