In human-computer interaction, low-key feedback is a type of

output Output may refer to: * The information produced by a computer, see Input/output * An output state of a system, see state (computer science) * Output (economics), the amount of goods and services produced ** Gross output in economics, the value o ...

that takes a background role by being very subtle, sometimes nearly imperceptible. Physical

machines A machine is a physical system using power to apply forces and control movement to perform an action. The term is commonly applied to artificial devices, such as those employing engines or motors, but also to natural biological macromolecul ...

often provide rich low-key feedback as a byproduct of their design. In

computer software Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work. At the lowest programming level, executable code consists ...

, the low-key feedback usually needs to be designed in. The benefit of low-key feedback is that it can provide always available indication without cluttering the

user interface In the industrial design field of human–computer interaction, a user interface (UI) 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 f ...

with explicit indicators such as text labels or indicator lights. The downside of low-key feedback is that it can be too subtle to some users and it often cannot be self-describing to beginners. For example, a person driving an

automobile A car or automobile is a motor vehicle with wheels. Most definitions of ''cars'' say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people instead of goods. The year 1886 is regarde ...

has several means of being informed about the operation of the

engine An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power ...

. In addition to the

dashboard For business applications, see Dashboard (business). A dashboard (also called dash, instrument panel (IP), or fascia) is a control panel set within the central console of a vehicle or small aircraft. Usually located directly ahead of the drive ...

lights, the driver also perceives the

sound In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' b ...

and

vibration Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point. The word comes from Latin ''vibrationem'' ("shaking, brandishing"). The oscillations may be periodic, such as the motion of a pendulum—or random, su ...

of the engine. An abnormal sound or vibration alerts the driver that there may be a problem, while a typical sound or vibration assures the driver that everything is going as normal. Making the automobile completely silent might negatively impact the performance of the driver, as he must expend additional effort to stay informed about the operation of vehicle. Similarly, a

computer program A computer program is a sequence or set of instructions in a programming language for a computer to execute. Computer programs are one component of software, which also includes documentation and other intangible components. A computer program ...

that has two modes of operation might employ low-key feedback to keep the user informed about the current mode. If the program had a view mode and an edit mode, background color of the workspace might subtly change from white to pale yellow when switching to edit mode. A

web browser A web browser is application software for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's screen. Browsers are used o ...

application could keep track of the pages the user has visited and alter the colors of links that point to pages the user has already viewed.

See also