chemistry

Mode (user interface)

Mode (user interface) is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Mode (user interface) rather than just read about it. In short: In user interface design, a mode is a state of a system in which user input is interpreted according to a particular set of rules. Larry Tesler defines mode as "a state of the user interface that lasts for a period of time, is not associated with any particular object, and has no role other than to place an interpretation on operator input." In his book The Humane Interface, Jef Raskin defines modality as: "An human…

Key takeaways

Mode (user interface) belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Mode (user interface) to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Mode (user interface) from memory before moving on to harder problems.

Reference excerpt

In user interface design, a mode is a state of a system in which user input is interpreted according to a particular set of rules. Larry Tesler defines mode as "a state of the user interface that lasts for a period of time, is not associated with any particular object, and has no role other than to place an interpretation on operator input." In his book The Humane Interface, Jef Raskin defines modality as:

"An human-machine interface is modal with respect to a given gesture when (1) the current state of the interface is not the user's locus 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).

Accordingly, 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 (from the Latin word locus, meaning "place" or "location"), also called heedstead in English. 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 in the place where interaction occurs. 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.

Modal

Examples of modal interfaces:

Keyboard caps lock When enabled, each letter key pressed is interpreted as the upper case version of that letter. When not enabled, letter key presses are interpreted as lower case. Keyboard insert/overwrite Keyboard input is usually affected by either insert mode or overwrite mode, toggled via the insert key. Bravo The first WYSIWYG modal editor made for Xerox Alto computers at Xerox PARC by Butler Lampson and Charles Simonyi. 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. Derivatives, such as Vim and Neovim. Emacs Has the concept of "prefix keys", which trigger a modal state by pressing the control key plus a letter key. Emacs then waits for additional keypresses that complete a keybinding. 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 multiple "major and minor" modes that change the available commands, and may be automatically invoked based on file type to more easily edit files of that type. Emacs modes are not restricted to editing text files; modes exist for file browsing, web browsing, IRC and email and their interaction patterns are equivalent to application software within the Emacs environment. Modes are written in Emacs Lisp, and all modes may not be included with all versions. Cisco IOS certain commands are executed in a "command mode". Palette tools Tools chosen from a palette in photo-editing and drawing applications are examples of a modal interface. Some advanced image editors have a feature where the same tools can be accessed nonmodally by a keypress, and remain active as long as the key is held down. Releasing the key returns the interface to the modal tool activated by the palette. In video games Video games can use game modes as a mechanism to enhance gameplay. Modal window Blocks all workflow in the top-level program until the modal window is closed.

Modeless A modeless interface does not have states in which different rulesets apply. A modeless interface avoids mode errors – when a user provides input that is interpreted differently than they expect since the mode (and associated ruleset) is not what they expect. Larry Tesler at PARC devised insights for a modeless word processor from the feedback gathered from a user test with newly-hired Sylvia Adams, where she was asked to ad lib some gestures to correct proofreading marks on the digital text. This test convinced Tesler's manager Bill English of the problems with their previous modal interface.

Mode error Modes are problematic because they can result in an error when the user not aware of what mode the interface is in, performs an action that is appropriate in a different mode, and gets an undesired response. A mode error can be startling, disorienting and annoying as the user copes with the violation of their expectations. Problems occur if a change in the system state happens unnoticed (initiated accidentally, by the system, or by another person), or if after some time the user forgets the current mode. Another common problem is a sudden change of state that interrupts a user's activity, such as focus stealing. In such a situation it the may perform operations with the old state in mind, while the brain has not yet fully processed the signals indicating the state change.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Mode (user interface)

Start with the simplest possible case. Write down what Mode (user interface) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Mode (user interface) before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Mode (user interface) ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Mode (user interface)

In research: Mode (user interface) appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Mode (user interface) in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Mode (user interface) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Graphical user interface elements, Human–computer interaction, User interface techniques, so understanding it makes those chapters shorter.
In everyday life: Look for Mode (user interface) outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Mode (user interface) in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Mode (user interface) means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Mode (user interface) out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Mode (user interface) in simple terms?

Why does Mode (user interface) matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Mode (user interface)?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Mode (user interface).