Glossary » d

“D” link

a “description link”; the letter “D” placed next to an image on a web page that links off to a text description of the image. This enables blind users or users of text browsers to understand the content of an…

damping factor

how far the pointer has to be moved before a click is considered a drag.

data mining

the use of statistical and visualization techniques to uncover trends and relationships within massive databases. Data mining is common with financial data, medical data, census data, and across the web as a whole. The trends sought after are often non-obvious…

data-centered interface

a user interface designed to support users editing object and documents and not designed around the use of application software. Users focus on documents without worrying about which applications are being used and possibly using multiple applications on the document…

data-driven error

when an automatic routine applies the wrong information because the wrong information was immediately available to perception.

dataflow diagram

a diagram similar to a circuit diagram used in workflow analysis, programming, and process management. It has a set of nodes and lines between the nodes indicating how information flows from one node to another.

For instance, in workflow analysis,…

dataglove

a glove with sensors to detect hand position and orientation, and finger position, used to provide 3-dimensional input, especially in virtual reality (VR) systems.

day-in-the-life studies

an approach to observational studies where one person is followed by the observer throughout a typical day and everything they do is recorded in order to get a detailed understanding of their work processes and work environment. By following a…

dead key

a key that modifies the output of the next key to be pressed, such as typing an accent followed by an “e” to get an “é” (Amiga term).

debriefing

after running a user study, explaining to a participant what happened and what the study is for, explaining any deception used in the study, asking for any remaining comments or concerns, and ensuring that the participant walks away with no…

decision support systems

software designed to facilitate decision-making, particularly group decision-making. Decision support systems may provide tools for such things as brainstorming, critiquing ideas, putting weights and probabilities on events and alternatives, and voting. Such systems enable presumably more rational and evenhanded decisions.…

decision tree

a visual representation of a decision problem intended to help people make better decisions. Each node represents either a choice by the decision-maker or a probabilistic outcome. A decision tree can be used to determine the probability and net…

decision tree analysis

a method for evaluating how users make decisions in performing their tasks. Through interviews and observations, a decision tree is created to model options a user must choose among in performing a task. The decision tree may be developed with…

declarative graphics system

software system to support the drawing of graphics through specifying the graphic objects that exist and their properties without having to specifically instruct the computer to draw at any specific time, in contrast to procedural graphics where each drawing command…

deep links

links from outside a website that go directly to a subpage of a website rather than the homepage, enabling direct linking to highly appropriate and specific content.

defect tracking

typically refers to identifying flaws appearing during manufacturing, which in software design normally pertains to the translation from design specs to finished software. The goal is not only to spot defects but to track them and identify the source of…

delay

a measure of the time it takes for a message to be transmitted across a network. The variance of the delay is also an important measure. Delay affects the perceived fluidity of a conversation and becomes a more serious problem…

delimited search

a search that requires a user to type an entire search string followed by a “delimiter character” (such as Return) to initiate a search, in contrast to an incremental search.

demand characteristics

a potential problem in user studies where people being studied have a tendency to behave in a way that reacts to what they think is expected of them. In user testing, for instance, people may tend to say an interface…

demand pull

technology development that is driven by user needs and requirements (demand), rather than by ideas or capabilities created by the development organization.

demographics

statistics representing the range and composition of your target audience, such as total market size and distribution of age, gender, education, income, computer experience, occupation, nationality, and system configurations.

depth perception

the experience of perceiving a third dimension of depth into a computer screen. For instance, windows add a certain depth by having shadows, and buttons indicate their dimensionality by having beveled edges.

Many different graphical qualities can act as depth…

described video

or descriptive video or audio captioning; provides audio descriptions of what appears in a video. Just as closed captions provide display text corresponding to the audio in a video, described video enables someone to hear what is being portrayed visually.…

description error

performing the right action for the wrong object, e.g. pouring your juice on your cereal in the morning instead of the milk.

descriptive metric

a value that describes some aspect of a system. For instance, if we were trying to automatically evaluate a web page, we might want to rate its “text legibility” based on a measure of the font size used. An automated…

design for evolution

or plan for obsolescence; organizations and computer systems are always in flux, so it is rare that a design can be made in a one-shot fashion without being terribly expensive to fix when the environment around it outgrows it. Therefore,…

design for manufacture

a term from industrial design that emphasizes the importance of making tradeoffs so that designs are actually practical to manufacture at reasonable costs, in a reasonable amount of time, given the resources, personnel, and tools available. User interface designers need…

design for yourself

a method of motivating an application’s features and user interface design by building a tool that the designers and/or programmers would use for themselves. This grounds the design in real-world requirements and ensures a rapid feedback loop between making design…

design rationale

the reasoning that leads to design decisions. Documenting design rationale is important for validating that the correct design decision was made, to help those who are trying to interpret ambiguous design decisions or examples that don’t fall clearly within a…

design space analysis

exploring design options and their implications, by considering pros and cons and dependencies between design decisions. Various methods include tradeoff analysis and decision tree analysis.

design-prototype-test cycle

a design process methodology of driving changes in design through successive instantiations of the design that are evaluated through some type of user testing, user feedback, or inspection technique.

1. design – generate ideas, analyze, and create solutions
…

designer management

the approach of having the designer of software manage the development project, thus ensuring that design considerations are not inappropriately compromised in the development process.

desktop metaphor

the representation of familiar desktop items in a user interface to help make the capabilities of a computer clear. The prototypical example is the Macintosh desktop which is used as a backdrop for all application windows and the surface on…

device independence

the ability for software to work with a variety of different input or output devices without having to worry about which ones exactly the user is using. This enables users, such as the disabled, to use whatever devices are most…

diagnostic evaluation

(formative evaluation) a usability evaluation specifically designed to diagnose the problems with a system in order to fix them, as opposed to a measurement study that merely attempts to rate or rank a system without identifying how to make an…

diagnostic pretesting

a marketing method for determining the subjective response users will have to a given design. During a preliminary mockup stage, designs are presented to individual users and focus groups to evaluate how engaging, attractive, and persuasive different options will be.…

dial

a widget that enables a user to set a value on a circular display, much as they would move a slider. Circular motion is usually quite difficult to control on-screen (especially with a mouse), so dials are best avoided.

dialog box

a type of window other than the main document window, commonly used to specify options or properties, and typically only visible temporarily.

…

Diamond Bullet

the company, Diamond Bullet Design, that created this Usability First website. Diamond Bullet specializes in usability evaluation and design services for internet and software products.

A “diamond bullet” is the typographic term for the diamond-shaped bullet points used in bulleted…

diary study

a study that asks people to keep a diary, or journal, of their interactions with a computer system, any significant events or problems during their use of a system, or other aspects of their working life. A diary typically asks…

dingbat

(graphic design) a small typographic element that can be placed among text, typically to draw attention to the text it marks (such as a bullet item). Many font families are available which consist solely of dingbats. Dingbats are typically…

direct manipulation

performing operations by making changes to data directly, such as clicking on it, dragging it, resizing it, and typing over it, as opposed to indirect operations, such as typing in commands on a command line or using menus and dialog…

DIS conference

Designing Interactive Systems; a biannual conference sponsored by ACM’s SIGCHI. DIS aims to bring together different disciplines in interaction design and demonstrate best practices in design.

disability

a mental or physical characteristic that limits the ability for someone to function at full capacity. Disabilities are frequently categorized into:

…

disability access

computer equipment and software designed to help people with disabilities to more effectively use them.

disclosure triangle

a small triangle pointing to the right which, when clicked, rotates to point down and reveals additional information below it.

discount usability

an approach to usability that seeks ways to optimize usability methods for cost-effectiveness. For instance, how can the number of users tested in user-testing be minimized while still maintaining the validity of the test? Can heuristics be found that will…

disk tree

a representation of hierarchical information with the primary node at the center and each successive descendant falling on concentric rings spanning out from the center. On each ring, a node is allocated space according to how many leaf nodes fall…

display inertia

the principle that when the display must be changed (during user input or a change in system state), the change is kept to the minimum necessary to reflect the changing information. Rather than updating the entire display, keep changes localized…

distance learning

learning in an environment where the instructor and the student are at different locations. Distance learning may take place through the mail, email, the web, and broadcast or two-way video. Distance learning offers the opportunity to reduce educational costs and…

distraction

anything that draws a users attention away from their current focus or desired focus, usually sounds or moving visual displays (such as blinking text, automatically scrolling text, animations, and flashing menubars).

On rare occasions, distractions can actually be useful for…

distributed architecture

an architecture for distributed applications which divides work among several processes. Generally no process has any privileged role in the application and the processes don’t depend on each other to continue operating.

distributed cognition

the notion of people thinking and solving problems collectively, rather than simply as isolated individuals. Those interested in distributed cognition are interested in how people communicate and jointly use artifacts to accomplish joint work.

diversion

any technique used to distract the user from the fact that the computer is busy processing so that the user doesn’t get bored, impatient, or frustrated. Techniques include presenting text to read, a picture, an animation, or a satisfying alternate…

diversity

things vary more than you’d ever expect. Users vary by preferences, skills, impairments, interests, language, and culture. Computers vary by operating system, processor speed, screen size, memory, and networking abilities.

Design for diversity, or expect to succeed with only a…

document management systems

systems for entering, tracking, routing, and processing documents, whether documents that were originally created electronically (email and online forms) or documents that are scanned (“imaged documents”). Document management systems form a subset of workflow systems, though they may also have…

documentation

manuals, help systems, and other materials used to introduce and explain a system to users. Manuals and readme files typically contain installation information. Manuals and help systems typically contain both reference information and how-to information (tutorials or “task-based” help information…

domain expert

or “subject matter expert” (SME); a person with special knowledge or skills in a particular area; a person extremely familiar with a given group of users and their work habits (because they belong to the group).

A truck driver is…

domain knowledge

or “subject matter expertise”; knowledge about a specific field of interest; knowledge about the content area for which a piece of software is being designed, as opposed to programming knowledge or usability expertise. For instance, when building medical software, physicians…

domain name

a name interpreted by internet software to determine which computer (which server) to access. For instance, diamondbullet.com is a domain name representing the company Diamond Bullet Design and which is translated by internet software to an IP address indicating the…

dome tree

like a disk tree, a representation of hierarchical information with the primary node at the center and each successive descendant falling on concentric rings spanning out from the center along a 3-dimensional dome. The dome allows relationships to be indicated…

doorway page

(or gateway page) a page designed as an entranceway to a website. The most common doorway is a homepage, but a doorway page can be a useful alternative entrance that appeals to a specific target audience. An example is to…

dot-coma

when a website is inaccessible due to too many simultaneous visitors, usually during major events such as a product release or a news item appearing with a link to the site.

double click

to click a button twice quickly in succession, typically on a mouse. This is used to indicate that the region currently under the mouse pointer should respond in some way distinct from how it responds to a single click, usually…

double tap

in a pen-based system, to tap a pen twice in succession, used in a way equivalent to a double-click to select a range or activate an icon.

drag

the operation of moving a graphical object across the computer screen, usually accomplished by pressing down the mouse button while the mouse pointer is over the object and moving the mouse with the button down, then releasing the mouse button…

drag and drop

a direct manipulation capability that allows you to select and drag and object and drop it into another location, specifically referring to dragging from one application to another. This is a more direct approach than the traditional cut and paste…

drag handle

a small box on the edge of a selected object that can be dragged to move the object.

drag texture

a texture that appears on draggable interface components, such as sliders, scrollbars, resize boxes, and window title bars. As a metaphor for real-world grippable objects, the texture is usually a sandpaper grid of dots or a set of parallel lines.…

drilldown

the act of navigating deeper thru a hierarchy of screens, often when the higher-level screens are intended only as navigation and the important content is only at the lowest level.

dropdown menu

in a menubar, an item you can click that brings down a list of options to choose, typically used to perform commands or set options.

Not always used to refer to items in a menubar, a menu can also appear…

DUX conference

Designing User Experiences; a conference that explores how to create a great user experience from a product lifecycle and professional viewpoint.

Dvorak keyboard

The most common alternative to the standard QWERTY keyboard; the Dvorak keyboard assigns letters to keys so that typing is fast. Primary alphabetic keys are arranged in three rows as follows:

‘,.PYFGCRL
AOEUIDHTNS
;QJKXBMWVZ

Unfortunately,…

dwell

the property of a control that keeps it from activating until it has been ‘held’ (or manipulated) for a certain period of time, thus preventing accidental activation from being briefly hit unintentionally.

dwell time

the time a user lingers at a certain step of a task, such as the time that a user holds the pointer over a button, or the time spent viewing an individual web page.

DWIM

do what I mean; an interface that allows flexible styles of user input and lets the user ask the computer to interpret “what-I-mean” (not what I say), generally involving a simple heuristic for guessing what the user is most likely…