Mode (computer interface)
Encyclopedia
In user interface
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...

 design, a mode is a distinct setting within a computer program
Computer program
A computer program is a sequence of instructions written to perform a specified task with a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute...

 or any physical machine interface, in which the same user input will produce perceived different results than it would in other settings.
The best-known modal interface components are probably the Caps lock
Caps lock
Caps lock is a key on many computer keyboards. Pressing it sets an input mode in which typed letters are uppercase by default. The keyboard remains in caps lock mode until the key is pressed again...

 and Insert
Insert key
The Insert key is a key commonly found on computer keyboards.It is primarily used to switch between the two text-entering modes on a personal computer or word processor. The first is overtype mode, in which the cursor, when typing, overwrites any text that is present on and after its current...

 keys on the standard computer keyboard
Computer keyboard
In computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...

, both of which put the user's typing into a different mode after being pressed, then return it to the regular mode after being re-pressed.

An interface that uses no modes is known as a modeless interface. Modeless interfaces intend to avoid mode errors by making it impossible for the user to commit them.

Definition

A precise definition is given by Jef Raskin
Jef Raskin
Jef Raskin was an American human-computer interface expert best known for starting the Macintosh project for Apple in the late 1970s.-Early years and education:...

 in his book "The Humane Interface
The Humane Interface
The Humane Interface: New Directions for Designing Interactive Systems is a book about user interface design written by Jef Raskin and published in 2000. It covers ergonomics, quantification, evaluation, and navigation.-Contents:...

":

"An human-machine interface is modal with respect to a given gesture
when (1) the current state
State (computer science)
In computer science and automata theory, a state is a unique configuration of information in a program or machine. It is a concept that occasionally extends into some forms of systems programming such as lexers and parsers....

 of the interface is not the user's locus [sic] of
attention and (2) the interface will execute one among several
different responses to the gesture, depending on the system's current
state." (Page 42).


In Raskin's sense and according to his definition, an interface is not modal as long as the user is fully aware of its current state. Raskin refers to this as 'locus of attention'. Typically a user is aware of a system state if the state change was purposefully initiated by the user, or if the system gives some strong signals to notify the user of the state change. If the user's locus of attention changes to a different area, the state of the interface may then represent a mode since the user is no longer aware of it.

Examples

Several examples of well-known software have been described as modal and/or using interface modes:
  • Text editor
    Text editor
    A text editor is a type of program used for editing plain text files.Text editors are often provided with operating systems or software development packages, and can be used to change configuration files and programming language source code....

    s - typically are in insert mode by default but can be toggled in and out of overstrike
    Overstrike
    In typography, overstrike is a method of printing characters that are missing from the printer's character set. It was widely used around the early 1990s...

     mode by pressing the Insert
    Insert key
    The Insert key is a key commonly found on computer keyboards.It is primarily used to switch between the two text-entering modes on a personal computer or word processor. The first is overtype mode, in which the cursor, when typing, overwrites any text that is present on and after its current...

     key.
  • vi
    Vi
    vi is a screen-oriented text editor originally created for the Unix operating system. The portable subset of the behavior of vi and programs based on it, and the ex editor language supported within these programs, is described by the Single Unix Specification and POSIX.The original code for vi...

     - has one mode for inserting text, and a separate mode for entering commands. There is also an "ex" mode for issuing more complex commands (e.g. search and replace). Under normal circumstances, the editor automatically returns to the previous mode after a command has been issued; however, it is possible to permanently move into this mode using Shift-Q.
  • Emacs
    Emacs
    Emacs is a class of text editors, usually characterized by their extensibility. GNU Emacs has over 1,000 commands. It also allows the user to combine these commands into macros to automate work.Development began in the mid-1970s and continues actively...

     - has a special mode for issuing commands, which is entered by pressing the control key plus a letter key. This differs from vi in that the mode always ends as soon as the command is called, when the sequence of key presses that activates it is completed. Emacs also has many "major and minor" modes that change the available commands, and are automatically invoked based on file type to more easily edit files of that type. Modes are written in Emacs Lisp
    Emacs Lisp
    Emacs Lisp is a dialect of the Lisp programming language used by the GNU Emacs and XEmacs text editors . It is used for implementing most of the editing functionality built into Emacs, the remainder being written in C...

    , and all modes may not be included with all versions.
  • Cisco IOS
    Cisco IOS
    Cisco IOS is the software used on the vast majority of Cisco Systems routers and current Cisco network switches...

     - in order to execute certain commands, you must enter a certain "command mode" that allows you to execute that command.
  • Also, tools chosen from a palette
    Palette (computing)
    In computer graphics, a palette is either a given, finite set of colors for the management of digital images , or a small on-screen graphical element for choosing from a limited set of choices, not necessarily colors .Depending on the context In computer graphics, a palette is either a given,...

     in photo-editing
    Photo manipulation
    Photo manipulation is the application of image editing techniques to photographs in order to create an illusion or deception , through analog or digital means.- Types of digital photo manipulation :...

     and drawing applications are examples of a modal interface.
  • Video games can use game modes as a mechanic to enhance gameplay
    Gameplay
    Gameplay is the specific way in which players interact with a game, and in particular with video games. Gameplay is the pattern defined through the game rules, connection between player and the game, challenges and overcoming them, plot and player's connection with it...

    .
  • Modal window
    Modal window
    In user interface design, a modal window is a child window that requires users to interact with it before they can return to operating the parent application, thus preventing the workflow on the application main window...

    s that block all workflow
    Workflow
    A workflow consists of a sequence of connected steps. It is a depiction of a sequence of operations, declared as work of a person, a group of persons, an organization of staff, or one or more simple or complex mechanisms. Workflow may be seen as any abstraction of real work...

     in the top-level program until the modal window is closed.

Mode errors

Modes are often frowned upon in interface design because they are likely to produce mode errors when the user forgets what state the interface is in, performs an action that is appropriate to a different mode, and gets an unexpected and undesired response. A mode error can be quite startling and disorienting as the user copes with the sudden violation of his or her user expectations
User expectations
User expectations refers to the consistency that users expect from products. Interaction design is very concerned with this topic. For example, our user expectations for traffic behavior is one of the more consistent ones because it is governed by traffic laws that are enforced...

.

Problems occur if a change in the system state happens unnoticed (initiated by the system, or by another person, such as the user who was previously using the machine), or if after some time the user forgets about the state change. Another typical problem is a sudden change of state that interrupts a user's activity, such as focus stealing
Focus stealing
In computing, focus stealing is a mode error produced when a program not in focus places a window in the foreground and redirects all keyboard input to that window...

. In such a situation it can easily happen that the user does some operations with the old state in mind, while the brain has not yet fully processed the signals indicating the state change.

A very frustrating type of modality is created by a mode where the user does not find a way out, or, in other words, where she cannot find how to restore the old system state.

Examples of mode errors

  • The most common source of mode errors may be the caps lock
    Caps lock
    Caps lock is a key on many computer keyboards. Pressing it sets an input mode in which typed letters are uppercase by default. The keyboard remains in caps lock mode until the key is pressed again...

     key. Other common modes available in PC keyboards are Insert
    Insert key
    The Insert key is a key commonly found on computer keyboards.It is primarily used to switch between the two text-entering modes on a personal computer or word processor. The first is overtype mode, in which the cursor, when typing, overwrites any text that is present on and after its current...

     and the other lock key
    Lock key
    LOCK is a function that locks part of a keyboard keys depending on the lock settings selected.Most keyboards have three different types of lock functions:*Number Lock – Num Lock*Capital Lock – Caps Lock...

    s, Num lock
    Num lock
    Num Lock is a key on the numeric keypad of most computer keyboards. It is a toggle key, like Caps Lock and Scroll Lock. Its state is commonly represented by an LED light built into the keyboard....

     and Scroll lock
    Scroll lock
    Scroll lock is a keyboard button on some computer keyboards. The key is not frequently used and therefore some keyboards lack Scroll Lock altogether....

    . Also dead key
    Dead key
    A dead key is a special kind of a modifier key on a typewriter or computer keyboard that is typically used to attach a specific diacritic to a base letter. The dead key does not generate a character by itself but modifies the character generated by the key struck immediately after...

    s for diacritics create a short-term mode, at least if they don't provide visual feedback that the next typed character will be modified.

  • A frequent example is the sudden appearance of a modal
    Modal window
    In user interface design, a modal window is a child window that requires users to interact with it before they can return to operating the parent application, thus preventing the workflow on the application main window...

     error dialog
    Alert dialog box
    An alert dialog is a colloquial term for a particular type of dialog box that occurs in a graphical user interface. It is also known as an alert box, alert window, error dialog, alert popup or plainly alert.The typical alert dialog provides information in a separate box to the user, after which...

     in an application while the user is typing, known as focus stealing
    Focus stealing
    In computing, focus stealing is a mode error produced when a program not in focus places a window in the foreground and redirects all keyboard input to that window...

    ; the user expects the typed text to be introduced into a text field, but the unexpected dialog discards all that input and may even interpret some keystrokes (like 'Y' or 'N' for 'yes' or 'no') incorrectly.

  • The Unix
    Unix
    Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...

     text editor
    Text editor
    A text editor is a type of program used for editing plain text files.Text editors are often provided with operating systems or software development packages, and can be used to change configuration files and programming language source code....

     vi
    Vi
    vi is a screen-oriented text editor originally created for the Unix operating system. The portable subset of the behavior of vi and programs based on it, and the ex editor language supported within these programs, is described by the Single Unix Specification and POSIX.The original code for vi...

     can be notoriously difficult for beginners precisely because it uses modes, and earlier versions configured mode indication to be turned off by default.

Assessment

Modes are intended to grab the user's full attention and to acknowledge the content present in them, in particular when critical confirmation from the user is required.
This later use is criticised by as ineffective for its intended use (protection against errors in destructive actions) due to habituation
Habituation
Habituation can be defined as a process or as a procedure. As a process it is defined as a decrease in an elicited behavior resulting from the repeated presentation of an eliciting stimulus...

. Actually making the action reversible (providing an "undo" option) is recommended instead. Though modes can be successful in particular usages to restrict dangerous or undesired operations, especially when the mode is actively maintained by a user as a quasimode.

Modes are sometimes used to represent information pertinent to the task that doesn’t fit well into the main visual flow. Modes can also work as well-understood conventions, such as painting tools..

Modal proponents may argue that many common activities are modal and users adapt to them. An example of modal interaction is that of driving motor vehicles. A driver may be surprised when pressing the acceleration pedal does not accelerate the vehicle in the forward direction, most likely because the vehicle has been placed in an operating mode like park, neutral, or reverse. Modal interfaces require training and experience to avoid mode errors like these.

Interface expert Jef Raskin
Jef Raskin
Jef Raskin was an American human-computer interface expert best known for starting the Macintosh project for Apple in the late 1970s.-Early years and education:...

 came out strongly against modes, writing, "Modes are a significant source of errors, confusion, unnecessary restrictions, and complexity in interfaces." Later he notes, "'It is no accident that swearing is denoted by #&%!#$&,' writes my colleague, Dr. James Winter; it is 'what a typewriter used to do when you typed numbers when the Caps Lock was engaged'." Raskin dedicated his book The Humane Interface
The Humane Interface
The Humane Interface: New Directions for Designing Interactive Systems is a book about user interface design written by Jef Raskin and published in 2000. It covers ergonomics, quantification, evaluation, and navigation.-Contents:...

 to describe the principles of a modeless interface for computers. Those principles were implemented in the Canon Cat
Canon Cat
The Canon Cat was a task-dedicated, desktop computer released by Canon Inc. in 1987 at a price of $1495 USD. On the surface it was not unlike the dedicated word processors popular in the late 1970s to early 1980s, but it was far more powerful and incorporated many unique ideas for data...

 and Archy
Archy
Archy is a software system whose user interface poses a radically different approach for interacting with computers with respect to traditional graphical user interfaces. Designed by human-computer interface expert Jef Raskin, it embodies his ideas and established results about human-centered...

 systems.

Some interface designers have recently taken steps to make modal window
Modal window
In user interface design, a modal window is a child window that requires users to interact with it before they can return to operating the parent application, thus preventing the workflow on the application main window...

s more obvious and user friendly by darkening the background behind the window or allowing any mouse click outside of the modal window to force the window to close – a design called a Lightbox
Lightbox (JavaScript)
Lightbox, and the newer Lightbox 2, is a JavaScript application used to display large images using modal dialogs. The script has gained widespread popularity due to its simple yet elegant style and easy implementation...

 – thus alleviating the risk of modal errors. Jakob Nielsen
Jakob Nielsen (usability consultant)
Jakob Nielsen is a leading web usability consultant. He holds a Ph.D. in human–computer interaction from the Technical University of Denmark in Copenhagen.-Early life and background:...

 states as an advantage of modal dialogs that it improves user awareness.

Larry Tesler
Larry Tesler
Larry Tesler is a computer scientist working in the field of human-computer interaction. Tesler has worked at Xerox PARC, Apple Computer, Amazon.com, and Yahoo!...

, of Xerox PARC
Xerox PARC
PARC , formerly Xerox PARC, is a research and co-development company in Palo Alto, California, with a distinguished reputation for its contributions to information technology and hardware systems....

 and Apple Computer
Apple Computer
Apple Inc. is an American multinational corporation that designs and markets consumer electronics, computer software, and personal computers. The company's best-known hardware products include the Macintosh line of computers, the iPod, the iPhone and the iPad...

, disliked modes sufficiently to get a personalized license plate for his car that reads: "NO MODES". He has used this plate from the early 1980s to the present, on various cars. Along with others, he has also been using the phrase "Don't Mode Me In" for years as a rally cry to eliminate or reduce modes.

Bruce Wyman, the designer of a multi-touch
Multi-touch
In computing, multi-touch refers to a touch sensing surface's ability to recognize the presence of two or more points of contact with the surface...

 table for a Denver Art Museum
Denver Art Museum
The Denver Art Museum is an art museum in Denver, Colorado located in Denver's Civic Center.It is known for its collection of American Indian art,and has a comprehensive collection numbering more than 68,000 works from across the world....

 art exhibition argues that interfaces for several simultaneous users must be modeless, in order to avoid bringing any single user into focus.

Avoid when possible

Alternatives to modes such as the undo
Undo
Undo is a command in many computer programs. It erases the last change done to the document reverting it to an older state. In some more advanced programs such as graphic processing, undo will negate the last command done to the file being edited....

 command and the recycle bin
Recycle bin (computing)
In computing, the trash is temporary storage for files that have been deleted in a file manager by the user, but not yet permanently erased from the physical media...

 are recommended when possible.
HCI researcher Donald Norman
Donald Norman
Donald Arthur Norman is an academic in the field of cognitive science, design and usability engineering and a co-founder and consultant with the Nielsen Norman Group. He is the author of the book The Design of Everyday Things....

 argues that the best way to avoid mode errors, in addition to clear indications of state, is helping the users to construct an accurate mental model
Mental model
A mental model is an explanation of someone's thought process about how something works in the real world. It is a representation of the surrounding world, the relationships between its various parts and a person's intuitive perception about his or her own acts and their consequences...

 of the system which will allow them to predict the mode accurately.

This is demonstrated, for example, by some stop sign
Stop sign
A Stop sign is a traffic sign to notify drivers that they must stop before proceeding.-Specifications:The Vienna Convention on Road Signs and Signals proposed standard stop sign diameters of 0.6, 0.9 or 1.2 metres. UK and New Zealand stop signs are 750, 900 or 1200 mm, according to sign...

s at road intersections. A driver may be conditioned
Conditioning
Conditioning may refer to:* In psychology, the process of performing some particular action to directly influence an individual's learning; see education...

 by a four way stop sign
Stop sign
A Stop sign is a traffic sign to notify drivers that they must stop before proceeding.-Specifications:The Vienna Convention on Road Signs and Signals proposed standard stop sign diameters of 0.6, 0.9 or 1.2 metres. UK and New Zealand stop signs are 750, 900 or 1200 mm, according to sign...

 near his or her home to assume that similar intersections will also be four way stops. If it happens to be only two way, the driver could proceed through if he or she sees no other cars. Especially if there is an obstructed view, a car could come though and hit the first car broadside. The stop sign alleviates the problem by showing small diagrams describing which of the directions have a stop sign and which don't, thus improving the situational awareness of drivers.

Proper placement

Modal controls are best placed where the focus is in the task flow. For example, a modal window can be placed near the GUI control that triggers its activation. Modal controls can be disruptive, so efforts should be made to reduce their capacity to block user work. After completing the task for which the mode was activated, or after a cancel action such as the Escape key, returning to the previous state when a mode is dismissed will reduce the negative impact.

Quasimodes

In the book The Humane Interface
The Humane Interface
The Humane Interface: New Directions for Designing Interactive Systems is a book about user interface design written by Jef Raskin and published in 2000. It covers ergonomics, quantification, evaluation, and navigation.-Contents:...

, Jef Raskin championed what he termed quasimodes, which are modes that are kept in place only through some constant action on the part of the user; such modes are also called spring-loaded modes.
The term quasimode is a composite of the latin prefix quasi (which means almost, to some degree) and the English word "mode".

Modifier key
Modifier key
In computing, a modifier key is a special key on a computer keyboard that modifies the normal action of another key when the two are pressed in combination....

s on the keyboard, such as the Shift key
Shift key
The shift key is a modifier key on a keyboard, used to type capital letters and other alternate "upper" characters. There are typically two shift keys, on the left and right sides of the row below the home row...

, the Alt key
Alt key
The Alt key on a computer keyboard is used to change the function of other pressed keys. Thus, the Alt key is a modifier key, used in a similar fashion to the Shift key. For example, simply pressing "A" will type the letter a, but if you hold down either Alt key while pressing A, the computer...

 and the Control key
Control key
In computing, a Control key is a modifier key which, when pressed in conjunction with another key, will perform a special operation ; similar to the Shift key, the Control key rarely performs any function when pressed by itself...

, are all examples of a quasimodal interface.

The application enters into that mode as long as the user is performing a conscious action, like pressing a key and keeping it pressed while invoking a command. If the sustaining action is stopped without executing a command, the application returns to a neutral status.

The purported benefit of this technique is that the user doesn't have to remember the current state of the application when invoking a command: the same action will always produce the same perceived result. An interface that uses quasimodes only and has no full modes is still modeless.

The StickyKeys feature turns a quasimode into a mode by serializing keystrokes of modifier keys with normal keys, so that they don't have to be pressed simultaneously. In this case the increased possibility of a mode error is largely compensated by the improved accessibility
Accessibility
Accessibility is a general term used to describe the degree to which a product, device, service, or environment is available to as many people as possible. Accessibility can be viewed as the "ability to access" and benefit from some system or entity...

 for users with physical disabilities.

See also

  • Automation surprise
    Automation surprise
    An automation surprise is when an automation system performs an action that is unexpected by the user. A mode error can be a common cause of an automation surprise. Automation surprise can be dangerous when it upsets the situational awareness of a control operator.-External links:* Rachid...

  • Error message
    Error message
    An error message is information displayed when an unexpected condition occurs, usually on a computer or other device. On modern operating systems with graphical user interfaces, error messages are often displayed using dialog boxes...

  • GUI
    Gui
    Gui or guee is a generic term to refer to grilled dishes in Korean cuisine. These most commonly have meat or fish as their primary ingredient, but may in some cases also comprise grilled vegetables or other vegetarian ingredients. The term derives from the verb, "gupda" in Korean, which literally...

  • Human computer interaction
  • Interaction design
    Interaction design
    In design, human–computer interaction, and software development, interaction design, often abbreviated IxD, is "the practice of designing interactive digital products, environments, systems, and services." Like many other design fields interaction design also has an interest in form but its main...

  • Modal window
    Modal window
    In user interface design, a modal window is a child window that requires users to interact with it before they can return to operating the parent application, thus preventing the workflow on the application main window...

  • Modalities and modes
  • State (computer science)
    State (computer science)
    In computer science and automata theory, a state is a unique configuration of information in a program or machine. It is a concept that occasionally extends into some forms of systems programming such as lexers and parsers....


External links

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