Glossary » Interaction Design

2-second rule

A loose principle that a user should not need to wait more than 2 seconds for certain types of system response, such as application-switching and application launch time. The choice of 2 seconds is somewhat arbitrary, but a reasonable order…

3-click rule

The principle that access to any feature of an application, or each logical step in a process, should require no more than 3 clicks. Applying this principle can be tricky because of the ill-defined nature of what constitutes a primary…

access key

A key on the keyboard used as a shortcut to issue menu commands (underlined items in Windows menus).

adaptive interfaces

user interfaces that change over time, in response to how they are used, to improve the quality of the interaction. Examples with current technology include speech and handwriting recognition systems that improve the accuracy of their recognition as they become…

affective interface

a user interface that appeals to the emotional state of users and allows users to express themselves emotionally.

affordance

a situation where an object’s sensory characteristics intuitively imply its functionality and use.

A button, by being slightly raised above an otherwise flat surface, suggests the idea of pushing it. A lever, by being an appropriate size for grasping, suggests…

alert box

a dialog box, generally modal, that appears to alert the user to important information.

3 categories of alert boxes are common:

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ambient media

devices that monitor information states and display the information continuously in the periphery (that is, without the user needing to consciously attend to the display). This allows the user to be aware of the peripheral information without making an explicit…

anticipation

in animation, preparation before an action so that the user has some foreshadowing of the action and can more effectively interpret the action. For instance, when a character runs away, the character will back off slightly in the opposite direction…

associative activation error

an error that occurs when a thought or related idea interferes with the current action when it isn’t appropriate (like a Freudian slip).

auditory feedback

sounds in response to user activity, such as a click after a keypress, a whoosh accompanying opening and closing windows, or a klunk when a file is deleted. Useful as redundant reinforcement of activities and for those who are visually…

augmented reality

systems that annotate physical objects and environments by displaying into the environment rather than on an independent display device. Typical display mechanisms include projectors that project displays onto physical desktops or head-mounted displays that are semitranslucent, allowing overlays to be…

auto-completion

(or auto-fill) a feature of text-entry fields that automatically completes typed entries with the best guess of what the user may intend to enter, such as pathnames, urls, or long words, thus reducing the amount of typing necessary to enter…

auto-exit

or auto-skip; in form fields with a fixed character size, the movement to the next field automatically on completion of the field, used to reduce keystrokes (by avoiding the necessity of tabbing to the next field).

automatic scrolling

scrolling that occurs when a user drags outside the visible region, such as when a user is selecting text across multiple pages. Automatic scrolling is any scrolling that occurs without a user having to explicitly scroll using a scrollbar.

balloon help

a help facility in Mac OS that displays a speech balloon over widgets and screen regions when the users pause over them. The speech balloon typically contains a title and a short description.

Similar in some ways to tooltips, except…

boolean search

a search that allows the user to enter logical expressions including AND, OR, and NOT. This is a common advanced search feature because of its ability to specify desired results very precisely. However, in natural language, “and” is frequently used…

breakdown analysis

a technique for analyzing user interaction sequences which looks at times when users are focused on figuring out how to use the system (a “breakdown”) versus times when users are performing their intended tasks.

capture error

a type of slip (a kind of error) where a more frequent and more practiced behavior takes place when a similar, but less familiar, action was intended. Examples include telling someone your home phone number when you intended to give…

case sensitivity

whether an application distinguishes between phrases based on whether the letters are upper case or lower case. If the distinction is relevant, then the system is case-sensitive. Otherwise, it is case-insensitive.

In search engines and in search-and-replace systems, case insensitivity…

chording

an input mechanism which requires pushing more than one button simultaneously in different patterns to represent different letters or commands.

“Chording keyboards” allow rapid entry of letters and words which can allow faster typing than conventional keyboards and permits one-handed…

clearly marked exits

a principle that users should be able to easily cancel or undo an undesirable operation; essentially the principle of reversibility or forgiveness. Examples include:

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click

the press and release of a button, typically on a mouse, to select or activate the region on the screen that the pointer is currently indicating, for instance, to select an icon or press an on-screen button.

command-line interface

a means of operating a computer by typing a text command at an on-screen prompt and hitting the Enter or Return key to issue the command. The computer then processes the command, displays whatever output is appropriate, and presents another…

concurrent help

help systems that are available alongside an application, not overtaking it, so that the user can continue working with the application while referring to the content of the help system. Balloon help and tooltips are examples where the help system…