User interface
The space where humans and machines interact effectively.
A user interface (UI) is the space where interactions between humans and machines occur, enabling effective operation and control of the machine while the machine feeds back information to aid decision-making. This broad concept encompasses the interactive aspects of computer operating systems, hand tools, heavy machinery controls, and process controls. The design of user interfaces draws on disciplines such as ergonomics and psychology, with the overarching goal of producing a user-friendly interface that makes operation easy, efficient, and enjoyable, requiring minimal input for the desired output.
User interfaces are composed of one or more layers, including a human–machine interface (HMI) that typically interfaces with physical input hardware (e.g., keyboards, mice, game pads) and output hardware (e.g., monitors, speakers, printers). A device implementing an HMI is called a human interface device (HID). Interfaces that bypass physical movement entirely, using only electrodes, are known as brain–computer interfaces (BCIs) or brain–machine interfaces (BMIs). Additional UI layers may interact with one or more human senses, including tactile (touch), visual (sight), auditory (sound), olfactory (smell), equilibria (balance), and gustatory (taste).
Composite user interfaces (CUIs) engage two or more senses. The most common CUI is a graphical user interface (GUI), combining tactile and visual elements. Adding sound creates a multimedia user interface (MUI). CUIs fall into three categories: standard, virtual, and augmented. Standard CUIs use conventional devices like keyboards and monitors. Virtual CUIs block the real world to create a virtual reality interface, while augmented CUIs overlay information onto the real world. A CUI that interacts with all human senses is called a qualia interface. CUIs can also be classified by the number of senses they engage, such as a 3-sense standard CUI (visual, sound, smell) or a 4-sense virtual reality interface (adding touch). In complex systems, the HMI is typically computerized, and the term human–computer interface is used. The engineering of these interfaces is enhanced by human factors engineering and usability engineering, which are part of systems engineering. Multimodal interfaces allow users to interact using more than one input modality.
- field
- Human–computer interaction, industrial design
- known_for
- Defining the space where humans and machines interact, including HMI, GUI, and BCI
- related_disciplines
- Ergonomics, psychology, human factors engineering, usability engineering
Lore & Background
The user interface is the part of a machine that handles human–machine interaction, with physical examples including membrane switches, rubber keypads, and touchscreens. In complex systems, the human–machine interface is typically computerized, and the term human–computer interface refers to such systems. The engineering of these interfaces is enhanced by considering ergonomics, with disciplines such as human factors engineering and usability engineering being part of systems engineering. Tools for incorporating human factors are developed based on computer science knowledge, including computer graphics, operating systems, and programming languages.
Reader's Guide
The concept of the user interface is central to human–computer interaction, defining how humans operate and control machines across diverse fields, from computer operating systems to heavy machinery. Its design draws on ergonomics and psychology to maximize usability, aiming for minimal input and output. The terminology distinguishes between user interface, operator interface, and human–machine interface (HMI), with HMI typically local to one machine and operator interface linking multiple pieces of equipment. Modern interfaces include graphical user interfaces (GUIs), multimedia user interfaces (MUIs), and composite user interfaces (CUIs) that engage multiple senses, such as virtual and augmented reality interfaces. The legacy of the user interface lies in its evolution from batch processing to immersive, multimodal systems that allow interaction through multiple senses, including tactile, visual, auditory, olfactory, equilibria, and gustatory interfaces.
Did You Know?
- User interfaces can include brain–computer interfaces (BCIs) that use no input or output devices except electrodes.
- Composite user interfaces (CUIs) interact with two or more senses; the most common is a graphical user interface (GUI).
- A qualia interface interacts with all human senses, named after the theory of qualia.
Frequently Asked Questions
What is a User interface (UI)?
A user interface is the interaction space between a human and a machine, allowing the person to operate and control the system while the machine returns information that supports the user's decisions.
What layers or types make up a User interface?
UI can span multiple layers, from human–machine interfaces (HMIs) that connect to physical input and output hardware, through graphical interfaces (GUIs), all the way to brain–computer interfaces (BCIs) that rely solely on electrodes.
What is the main goal of User interface design?
The aim is to craft an interface that feels user-friendly so that operating the system is easy, efficient, and enjoyable while demanding as little input from the user as possible.
Which academic fields does User interface belong to?
UI sits at the intersection of human–computer interaction and industrial design, and it draws heavily on ergonomics, psychology, human factors engineering, and usability engineering.
Why is User interface important in communication and media?
It is the critical bridge that lets people direct machines and receive meaningful feedback, making every human–machine exchange—whether typing on a keyboard or reading neural signals—practical and purposeful.
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