User interface

The user interface, in the industrial design field of human–machine interaction, is the space where interaction between humans and machines occurs. The goal of interaction between a human and a machine at the user interface is effective operation and control of the machine, and feedback from the machine which aids the operator in making operational decisions. 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.

A user interface is the system by which people (users) interact with a machine. The user interface includes hardware (physical) and software (logical) components. User interfaces exist for various systems, and provide a means of:

Generally, the goal of human-machine interaction engineering 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 human.

Ever since the increased use of personal computers and the relative decline in societal awareness of heavy machinery, the term user interface has taken on overtones of the graphical user interface, while industrial control panel and machinery control design discussions more commonly refer to human-machine interfaces.

Other terms for user interface include human–computer interface (HCI) and man–machine interface (MMI).

Contents

Introduction

To work with a system, users have to be able to control and assess the state of the system. For example, when driving an automobile, the driver uses the steering wheel to control the direction of the vehicle, and the accelerator pedal, brake pedal and gearstick to control the speed of the vehicle. The driver perceives the position of the vehicle by looking through the windshield and exact speed of the vehicle by reading the speedometer. The user interface of the automobile is on the whole composed of the instruments the driver can use to accomplish the tasks of driving and maintaining the automobile.

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 direct neural interface. However, this latter usage is seeing increasing application in the real-life use of (medical) prostheses—the artificial extension that replaces a missing body part (e.g., cochlear implants).

In some circumstance 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.

Usability

Main article: Usability
See also: mental model, human action cycle, usability testing, and ergonomics. List of human-computer interaction topics

User interfaces are considered by some authors to be a prime ingredient of Computer user satisfaction. 

The design of a user interface affects the amount of effort the user must expend to provide input for the system and to interpret the output of the system, and how much effort it takes to learn how to do this. Usability is the degree to which the design of a particular user interface takes into account the human psychology and physiology of the users, and makes the process of using the system effective, efficient and satisfying.

Usability is mainly a characteristic of the user interface, but is also associated with the functionalities of the product and the process to design it. It describes how well a product can be used for its intended purpose by its target users with efficiency, effectiveness, and satisfaction, also taking into account the requirements from its context of use.

User interfaces in computing

In computer science and human-computer interaction, the user interface (of a computer program) refers to the graphical, textual and auditory information the program presents to the user, and the control sequences (such as keystrokes with the computer keyboard, movements of the computer mouse, and selections with the touchscreen) the user employs to control the program.

Types

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.

Currently (as of 2009) the following types of user interface are the most common:

User interfaces that are common in various fields outside desktop computing:

Other types of user interfaces:

See also:

History

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

Consistency

A property of a good user interface is consistency. Good user interface design is about getting a user to have a consistent set of expectations, and then meeting those expectations. Consistency can be bad if not used for a purpose and when it serves no benefit for the end user, though; like any other principle, consistency has its limits.[2]

Consistency is one quality to trade off in user interface design as described by the cognitive dimensions framework. In some cases, a violation of consistency principles can provide sufficiently clear advantages that a wise and careful user interface designer may choose to violate consistency to achieve some other important goal.

There are three aspects identified as relevant to consistency.[3]

First, the controls for different features should be presented in a consistent manner so that users can find the controls easily. For example, users find it difficult to use software when some commands are available through menus, some through icons, some through right-clicks, some under a separate button at one corner of a screen, some grouped by function, some grouped by “common,” some grouped by “advanced.” A user looking for a command should have a consistent search strategy for finding it. The more search strategies a user has to use, the more frustrating the search will be. The more consistent the grouping, the easier the search. The principle of monotony of design in user interfaces states that ideally there should be only way to achieve a simple operation,[4] to facilitate habituation to the interface.

Second, there is the "principle of least astonishment". Various features should work in similar ways.[5] For example, some features in Adobe Acrobat are "select tool, then select text to which apply." Others are "select text, then apply action to selection."[6] Commands should work the same way in all contexts.

Third, consistency counsels against user interface changes version-to-version. Change should be minimized, and forward-compatibility should be maintained. Generally, less mature software has fewer users who are entrenched in the status quo. Older, more broadly used software must more carefully hew to the status quo to avoid disruptive costs. For example, the change from the menu bars of Microsoft Office 2003 to the ribbon toolbar of Microsoft Office 2007 caused mixed reactions. The new interface caused rejection among advanced users,[7] who reported losses in productivity,[8] while average users reported improved productivity [9] and a fairly good acceptance.[10]

Modalities and modes

Main articles: Modality (human-computer interaction) and Mode (computer interface)

Two words are used in UI design to describe different ways in which a user can utilize a product. Modality refers to several alternate interfaces to the same product, while mode describes different states of the same interface.

A modality is a path of communication employed by the user interface to carry input and output. Examples of modalities:

The user interface may employ several redundant input modalities and output modalities, allowing the user to choose which ones to use for interaction.

A mode is a distinct method of operation within a computer program, in which the same input can produce different perceived results depending of the state of the computer program. For example, caps lock sets an input mode in which typed letters are uppercase by default; the same typing produces lowercase letters when not in caps lock mode. Heavy use of modes often reduces the usability of a user interface, as the user must expend effort to remember current mode states, and switch between mode states as necessary.

See also

References

  1. ^ appleinsider.com
  2. ^ "How to avoid foolish consistency". http://www.scottberkun.com/essays/5-how-to-avoid-foolish-consistency.  "People don’t like to learn things. If they take the time to learn something, they expect to be able to apply that knowledge in many places. It follows that good designers conserve the number of things users need to learn to get stuff done. ... In rare cases, consistency can become a self-perpetuating monster: It has to be used for a purpose. A foolish consistency is one that serves no benefit for the end user. Making things look and work the same is pointless if the user can no longer accomplish their tasks. Rank making things useful above making them consistent. ... Consistency is great because people like predictable things. They will feel comfortable when they can rely on different parts of your product to do exactly what they think it will do."
  3. ^ David E. Boundy (October 1991). "A taxonomy of programmers". ACM SIGSOFT Software Engineering Notes 16(4) 23-30. alcor.concordia.ca. http://alcor.concordia.ca/~smw/home/resources/taxonomy.html. 
  4. ^ Summary of design rules from The Humane Interface
  5. ^ For example, inconsistent user interface was one of the major causes of the Three Mile Island nuclear accident in 1979. Some indicator lights indicated normal as red, some as green. iem-inc.com
  6. ^ help.adobe.com
  7. ^ “For one thing, Word 2007 uses the entirely new ribbon interface. … ‘People will get used to the new interface, but at major efforts in time, training and cost,' says [a] director of systems … When it came time to move [a user] from 2003 to 2007… ‘I might as well of hit her over the head with a bat,’ he says. ‘I could see anger and frustration.’” Power users said it "takes too much time and patience to learn" the new interface. Word 2007: Not Exactly a Must-Have
  8. ^ An online survey by an Excel user group reports that about 80% of respondents had a negative opinion of the change, and within that 80%, the self-estimated reduction in productivity was "about 35%", "Ribbon survey results". http://www.exceluser.com/explore/surveys/ribbon/ribbon-survey-results.htm. 
  9. ^ "'Other readers feel it's worth taking the time to learn the new interface. Once you do, they say, it actually makes creating professional-looking documents much easier for the average user.'" Word 2007: Not Exactly a Must-Have The usual solution in providing a new user interface is to provide a backwards-compatibility mode, so that a product's most intensive users are not forced to bear the costs of the change.
  10. ^ "Dostál, M. User Acceptance of the Microsoft Ribbon User Interface". http://www.wseas.us/e-library/conferences/2010/Faro/DNCOCO/DNCOCO-25.pdf. , In: Advances in data networks, communications, computers. pp 143-149, WSEAS Press, 2010. ISBN 978-960-474-245-5

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