Glossary » c

CAI

computer-aided instruction; the use of computers in training and education. Traditional techniques of computer-aided instruction included drill-and-practice programs and approaches inspired by artificial intelligence research which used models of learning to model errors learners were making to customize lessons to…

call control

same as session control; the mechanism for determining who is involved in a call (session) and for setting up the call. A call is the term used most frequently for telephone sessions. The term session is used more often in…

callback

a programming technique common in user interface toolkits. A function can be registered as a callback for an object in the system, which causes the function to be called whenever some event takes place on the object. For instance, a…

candy box

in website design, a small box or sidebar that may appear anywhere within a page that hilites interesting tidbits, quotes, small ads, asides, or chunks of related navigation. Often it is a small graphic used like a banner ad and…

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…

card sorting

a technique for uncovering the hierarchical structure in a set of concepts by having users group items written on a set of cards, often used, for instance, to work out the organization of a website.

For a website, users would…

caret

a small triangle used as an insertion-point indicator in text entry.

carpal tunnel syndrome

(CTS) a problem with swelling or inflammation around the median nerve in the wrist, causing pain or numbness. Poor wrist support and posture during extensive typing is considered a contributing factor. Some ways to prevent it include improved posture, wrist…

cascading menu

a hierarchical menu or submenu; a menu with items that open up further submenus.

cascading stylesheets

CSS; a method for specifying the look of a web page independent of the markup of the structure of that page.

The original intent in HTML markup was to specify the structure of a page and allow the individual user…

CASE

computer-aided software engineering, a field that examines how computer tools can be used to support programmers. Examples include tools for visualizing software code, tracking bugs, and organizing software projects.

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…

case study

an intensive analysis of a specific example. Case studies are useful for providing an in-depth understanding of complex situations and for suggesting models and mechanisms to integrate with theories. Case studies can also be quite powerful in providing demonstrations that…

CAUSE

computer-aided usability engineering; tools to automate usability, such as screen layout tools, design checkers, event logging, automated usability testing, diagramming tools, task analysis tools, & tools for software localization.

centralized architecture

an architecture for distributed applications, which may involve multiple processes and which depends on one central process to serialize all events. Serialization is necessary to make sure that actions performed by multiple participants in a conversation are in a single…

change bars

lines along the edge of text that indicate where changes have been made since the previous version of the text. These are useful when multiple people have been editing a document together and need to track each other’s work. Change…

chat

software that enables multiple people in realtime to write messages in a public space, usually in typewritten text. As each person submits a message, it appears at the bottom of a scrolling screen.

Chat groups are usually formed by having…

chauffeured prototype

a prototype, typically done as a paper-and-pencil version of the interface, that the designer walks through with the user and manually demonstrates how the interface would respond to user actions. For example, the user might say “I’d click this button”,…

checkbox

a small box used in forms or dialog boxes that users can check on or check off. Unlike radio buttons, checkboxes are mutually exclusive – the value of one checkbox is usually entirely independent of the value of any other.…

CHI

computer-human interaction, pronounced “KIE” (hard k, long i). HCI is the most common term for the field, but CHI is the term used (probably because it’s easier to pronounce) for the annual CHI conference sponsored by ACM SIGCHI (special interest…

chiseled appearance

The appearance that lines have been etched into a surface, by using adjacent dark and light lines casting the correct shadow (usually assuming a top-left light source). This style should be avoided for text because of its poor legibility. In…

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…

chrome

a visual style for user interfaces that presents widgets as beveled 3-dimensional objects, usually with a gray, metallic appearance. In this style, buttons are presented as raised rectangles, text-entry fields and other content areas usually appear in beveled insets, and…

chromostereopsis

a phenomenon of visual perception: different wavelengths of light focus at slightly different depths in the eye. Thus, it is difficult to focus on an image that combines two colors because each color is fuzzy when the other color is…

claims analysis

analyzing the relationship of design parameters to the usability of an interface. A claim is a statement that a certain aspect of a design, such as the location of a button, the interactive style of a scrollbar, or the feedback…

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:

…

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.

click wheel

the thumbwheel on an iPod music player that allows scrolling through options with a circular motion of the thumb and can also be pressed in one of 4 directions to activate other commands (on the iPod: menu, back, forward, and…

clinical trial

testing a system in a clinical setting; that is, in a hospital, clinic, doctor’s office, etc. User testing and feature testing in such an environment has special limitations, especially because of the potential for unexpected effects on patient care. User…

clinical workstation

a computer in a clinical setting. Clinical workstations will usually need to provide some of the following capabilities:

…

clipboard

an abstract location where data is stored after it is cut or copied. The clipboard may actually be viewed when the items it contains have a natural visual representation, such as pictures or text.

clipping

a file that contains a small piece of text, graphics, or other object that has been dragged onto the desktop from an application, in contrast to a standard document saved by an application. The clipping can be dragged into another…

close box

a small box in the title bar of a window used to close the window.

closed captions

a visual text view of audio that is in a sound byte or video clip. Closed captions are an excellent provision for the hearing impaired, for nonnative speakers who may find written language easier to understand than spoken language, and…

closed card sort

a type of card sort that asks users to sort topics into pre-defined categories, as opposed to asking the users to label the categories. Users are provided with a list of topics (e.g. content pieces to go on a website)…

clown-invariant research design

an empirical study designed to be sufficiently robust, both in the effect being studied and in the method of the study, that you get the same results even if the investigator is wearing a clown suit.

CMN-GOMS

Card, Moran, and Newell GOMS. CMN-GOMS adds hierarchical structure to the Keystroke Level Model (KLM) version of GOMS. Tasks are organized as a series of goals and subgoals and operators are organized into subroutines called methods. CMN-GOMS can provide task…

CMYK

cyan-magenta-yellow-black; a color model that specifies any given color as the combination of 4 base colors, commonly used in printers. While the RGB model is based on combining projected colors (an additive system), the CMYK model is based on using…

co-discovery method

also “constructive interaction”; a user-testing technique where users work collaboratively to solve problems on a computer. The advantage over single-person testing is that the users talk about what they are doing naturally (as opposed to using a think-aloud protocol) and…

co-located

group activity that takes place in a specific location; co-located groupware is groupware designed for users who are at the same location, thus generally eliminating the need for phone or videophone connections, but often creating challenges in providing anonymity and…

coaching method

an approach to usability testing that involves a user and an expert coach. Instead of disallowing questions, users are encouraged to ask questions of the coach, who responds with appropriate instruction. By hearing typical user questions, problems are identified and…

cognetics

cognitive engineering; the study of human mental abilities, their limitations, and the application of this in design.

cognitive artifact

a physical object (or software application) used in the process of thinking, remembering, and problem-solving. Many types of drawings (on paper, whiteboards, and blackboards) can support thinking, and many software applications are specifically designed to help people solve problems (such…

cognitive dimensions

T.R.G. Green’s design principles for notations & programming language design. He emphasizes that because there are tradeoffs among these, they cannot be “guidelines” but must be viewed as discussion points, but of course, all guidelines involve tradeoffs.

…

cognitive impairment

any limitation in the ability to think or reason that affects a person’s capacity to perform a task. Cognitive impairments can be congenital or the result of a head injury, stroke, or disease. Head injuries in particular can result in…

cognitive load

the level of effort associated with thinking and reasoning (including perception, memory, language, etc.), thus potentially interfering with other thought processes. A user interface strives to minimize the cognitive load associated with operating the interface itself so that all of…

cognitive modeling

producing a computational model for how people perform tasks and solve problems, based on psychological principles. These models may be outlines of tasks written on paper or computer programs which enable us to predict the time it takes for people…

cognitive psychology

a branch of psychology whose focus on phenomena such as learning, memory, perception, and problem-solving lends itself well to applications in human-computer interaction.

Cognitive psychology is often characterized by the common use of experimental research methods and formal mathematical or…

cognitive walkthrough

an approach to evaluating a user interface based on stepping through common tasks that a user would need to perform and evaluating the user’s ability to perform each step. This approach is intended especially to help understand the usability of…

collaborative drawing

2 or more people conversing with the use of drawings or working together to create a drawn artifact. Conversing and creating an artifact are very different types of tasks, though there exists a continuum between them, such that it’s difficult…

collaborative inquiry

Inquiry is the investigation of users and their context in order to understand their problem space, their goals, and associated design constraints, usually by observational methods, surveys, and interviews. Collaborative inquiry involves the users (or potential users) of an application…

collaborative writing

multiple people composing text together. Collaborative writing systems may provide both realtime support and non-realtime support. Word processors may provide asynchronous support by showing authorship and allowing users to track changes and make annotations to documents. Authors collaborating on a…

collaboratory

a distributed research group coordinating their activities through electronic communication, remote instrumentation, and shared data analysis tools.

collapse box

a box used in a window’s title bar (in MacOS) that causes the window to shrink or expand, leaving only the title bar visible in its shrunken state. This functionality has also been called WindowShade, metaphorically referring to the idea…

color blindness

an inability to distinguish certain color combinations. About 8% of males and 0.5% of females are colorblind in some fashion, so it is common enough to be a highly-significant factor in design. Red-green color blindness is most common, followed by…

combo box

a text entry field which also has a menu to choose default values from, often used for choosing font sizes.

command key

or Apple key; a key on the Macintosh used as a shortcut to issue commands, by holding down the command key and pressing another letter. The command key is usually labeled with a small cloverleaf symbol on the Macintosh. The…

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…

Common User Access

CUA; a set of user interface standards established for IBM platforms in 1987.

commons problem

a problem in group behavior where what is best for an individual will actually be harmful for the group as a whole.

If a village has a Commons area for grazing cattle then this Commons area can be a strong…

comp

(graphic design) a rapidly-drawn but high-quality sketch intended for presentation purposes. Traditionally comps are created as quick color sketches done in marker, often used for client presentations especially in advertising and architecture. A comp is usually intended to be a…

comparative study

a study whose purpose is to compare 2 or more products, such as a user testing comparison to make sure that a new version of a product has fewer problems than the prior version. Another type of comparison is a…

competitive analysis

a set of methods for getting ideas from your competition, whether through reverse-engineering their user interface design rationale, determining common user interface conventions, or finding usability problems that can be fixed.

Results of a competitive analysis can be used in…

competitive user testing

a comparison of 2 or more user interfaces from competitive products used for marketing or product design purposes. When used for marketing, fairly rigorous procedures must be applied to ensure the accuracy and credibility of the result.

complaint tracking

taking user complaints and categorizing them for later followup in improving a user interface. Particularly common for websites, where complaints usually arrive through email and may come in large numbers. Complaints are categorized and prioritized (in a kind of triage…

composite selection

a selection that contains multiple items, especially a discontinuous selection.

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…

cone tree

a way of displaying hierarchical data (such as org charts or directory structures) in 3 dimensions. Branches from any node are spread out in a cone. This allows a denser layout than traditional 2-dimensional diagrams, though nodes may be obscured.…

confidentiality

in collecting data in user studies, confidentiality guarantees a person that their data will not be released in a way that it can be tracked to them as an individual. Anonymity is slightly different, in that it guarantees that a…

confirmation slip

a dialog box for confirming or canceling an action (NewtonOS term).

confound

any factor that might serve as an alternative (and generally undesirable) explanation for a result seen in a study, such as non-randomized samples, practice and history effects, and any arbitrary differences between things that are being compared.

consistency

the principle that things that are related should be presented in a similar way and things that are not related should be made distinctive. Consistency applies across quite varied contexts:

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consistency inspection

a quality control technique for evaluating and improving a user interface. The interface is methodically reviewed for consistency in design, both within a screen and between screens, in graphics (color, typography, layout, icons), text (tone, style, spelling), and interaction (consistency…

constraint

a declarative specification of relationships between variables. These relationships are automatically maintained by the system. Among other applications, constraints are used in graphics systems to specify layout, e.g. by specifying that two objects should always be connected with a line…

construct validity

the degree to which the testing tool and measurement tool used in a study accurately reflect the conceptual question of interest. For instance, asking people whether they feel that a product is usable is not necessarily an accurate measure of…

content blueprint

a specification for the content that will be needed in creating a website or multimedia presentation. The blueprint specifies every page or screen and what components are needed for each. A typical way to specify the necessary elements is to…

context of use

the situational factors that influence the use and usability of a system, including environmental factors (physical conditions such as space, time, temperature, noise), organizational factors (social network, management and organizational pressures, and work processes), and technical/system factors (network connectivity, system…

context-sensitive help

helpful information available within a task that is specific to the current activity of the user, as opposed to being general in nature.

contextual inquiry

a structured technique for gathering field data through interviewing (in a participatory design sense) and collecting information about the environment (the context).

contextual menus

menus that appear at the location of the pointer which give information relevant to the specific object or location being clicked, e.g. menus that appear after a right-click on a mouse (for PCs) or a control-click (Macs). These are in…

control

a type of widget that specifically enables a user to interact with it to provide input, as opposed to a widget that merely displays a value (e.g. a gauge). Example include most of the common widgets: buttons, scrollbars, text entry…

control key

CTRL; a key on used as a shortcut to issue commands (such as menu commands) and to type in certain non-alphanumeric values by holding down the control key and pressing another letter. The control key has been around a long…

control selectivity

the degree to which a control can be manipulated without accidentally activating other controls. A common problem is to position buttons or keys too closely, leading to the wrong button being pressed.

control sensitivity

the ease with which a control can be activated or set to a certain level. Less sensitive devices require greater effort.

controlled vocabulary system

any interface that is limited to the use of a small vocabulary. This applies to command-line systems, but usually refers to natural language and spoken language systems that, in order to produce consistent, predictable results, limit the number of recognized…

convenience

the degree to which accessing and using an interface is comfortable, and possible without excessive effort, mental or physical. The lack of deterrents to use, including organizational and social deterrents, schedule constraints, system availability, learning threshold, system delays, and prerequisites…

convention

a systematic approach to design that is established through consistent usage within a design community. Conventions are de facto standards, established not by the dictate of authority, but through implicit agreement and imitation.

Some common conventions include:

…

conversation analysis

a technique generally used for analyzing multi-user interactions, such as spoken conversations in a meeting. Conversation analysis is focused on detailed analysis of naturalistic transcripts of conversations.

conversational prop

an object used in a conversation, serving as the focus of the conversation, to provide context, or simply to clarify a point. In general, communication is achieved through 3 primary mechanisms: speech; gestures of the hands, face, and body; and…

conversion

on a website or web application, a conversion is any action taken by a user that satisfies the website owner’s business goals. Common examples include signing up for an email newsletter, making a purchase, or viewing an important web page.…

conversion rate

the percentage of people who achieve a given task from a given starting point. On websites, the percentage of people starting at page A who get to page B. So for instance, if 1000 come to a homepage on a…

corrector view

a special display for editing objects. In particular, in pen-based systems, the corrector view enables the easy correction of words that were incorrectly recognized from handwriting.

cosmesis

the effect that the appearance of a device has on the perception of the person who is using it; it’s “fashion statement”. The degree to which the user can feel attractive and socially acceptable in using the device.

cost justification

providing an economic argument for usability, for instance, by providing the value proposition…

Developer value proposition:

…

cost-benefit analysis

a comparison of the cost of a new system to the benefits of its use. This helps to evaluate the value of adopting new computer equipment and also to evaluate the merits of performing usability analyses and redesigning a user…

cost-effectiveness evaluation

a comparison of the cost of implementing a new information system or upgrading an existing one to the costs that would be involved in retaining the existing way of doing things (i.e. the legacy system or the non-computerized approach). A…

counterbalancing

A technique in experimental design that is used to avoid the introduction of confounding variables. In usability testing, this technique is most commonly used when establishing task order.

For example, a website user test might ask…

coupling

used to refer to the sharing of information between users, including which objects get shared and how often changes get transmitted between users. Tight coupling refers to situations where almost all information is shared between users and changes are transmitted…

course map

a flowchart that depicts learning paths for specific groups of learners who will be taking an online course. Used to determine course segmenting, navigation structures, and placement of shared content and resources on the interface design.

CPM-GOMS

Cognitive Perceptual Motor GOMS. CPM-GOMS is a cognitive modeling technique based on CMN-GOMS with an emphasis on parallel activities. Where other GOMS techniques assume that humans do one thing at a time, CPM-GOMS assumes as many operations as possible will…

CPR

computer-based patient record, a computer system for clinical use to record and retrieve patient information and patient care, and to provide a wide variety of other tools to both clinical and non-clinical staff, possibly in almost any clinical setting, from…

CRAP

contrast-repetition-alignment-proximity; a mnemonic for remembering 4 important principles of visual layout. These are closely related to the gestalt principles of similarity, good continuation, and proximity.

The term comes from Robin Williams’ “The Non-Designer’s Design Book”.

creeping featurism

the tendency for every new version of software to have more features than the last, in time resulting in an application with an unwieldy number of features that detracts from usability.

Also called “feature cascade”, a much less exciting way…

criterion testing

user testing that measures user performance to determine whether a target performance level has been reached. Typically a project will begin by determining usability requirements in terms of target performance along various benchmarks, e.g. “starting from the website homepage, the…

critical incident analysis

critical incidents are events that represent significant failures of a design, such as when a user accidentally unplugs the computer by kicking the power cords under the desk or when a nuclear powerplant goes critical because an operator thought that…

critical mass

the number of people who need to be using a system before it can be successful; often thought of as the number of people contributing in a groupware system to make the value of the system to each individual greater…

cross-platform compatibility

interoperability or platform-independence; the ability for devices or software applications to work with more than one hardware platform or operating system. Broad compatibility with various systems is critical to having a large market for a product (reaching your entire user…

crossbeam pointer

a pointer in the shape of a thick cross, used to select cells in a spreadsheet or table (different from a crosshair pointer, which is a thin cross used to carefully pinpoint exact locations).

crosshair

a pointer in a cross shape for accurate pointing, used commonly in drawing applications.

crosslink

a link that goes from one part of a website to another part of the website that is not in the same hierarchical branch, thus breaking out of the pure hierarchy.

Hierarchies are often a very clear organization for a…

CRT

cathode ray tube; the traditional technology used for televisions and computer monitors which technically involves shooting an electron beam into phosphors embedded in the screen to temporarily light them up.

CRUD

create-report-update-delete; a mnemonic for remembering the 4 basic operations in administering a database.

CSCL

computer-supported collaborative learning, the use of groupware tools in collaborative learning situations.

Tools might include email, videoconferencing, or any other tool that people might use to work together or for collaborative problem-solving, such as collaborative writing systems and scientific collaboration…

CSCW

computer-supported cooperative work. The field of study that examines how technology affects group interaction, and how technology can best be designed and built to facilitate group work.

Despite the name, this field of study doesn’t restrict itself to issues of…

CSME

computer-supported meeting environments.

CSMR

computer-supported meeting rooms.

cue cards

a form of help system that displays tips in a small window (a “card”) during each step of a task.

cursor

an indicator that marks the location of the text insertion point, usually a thin vertical blinking line or a small caret (upward-pointing triangle) at the base of the line of text.

Note: “cursor” is often mistakenly used to refer…

cursor key

a key on the keyboard that moves the cursor position up, down, left, or right. On keyboards without them, this is often simulated with the numeric keypad used to move the cursor, or some key combination used to indicate cursor…

customer experience

the user experience, mostly called “customer experience” when referring to e-commerce websites; the totality of the experience of a user when visiting a website. Their impressions and feelings. Whether they’re successful. Whether they enjoy themselves. Whether they feel like coming…

customer loyalty

a measure of the success of a design is how frequently the user uses it, how often users return to a website, how often they recommend it to friends, and how often they buy similar products from the same company…

customer support

sometimes “tech support”; assistance provided to a user after the purchase of software to solve problems with the product, such as bugs, installation problems, data recovery, usability problems, and so forth. This support is often available through a hot line,…

customization

the ability for a user to set the characteristics of a system to suit their preferences and needs. In desktop software, this is typically done with a “Preferences…” option. Customization may be related to superficial characteristics, such as the skin…

cut and paste

a simple device for users to move items/data into different parts of a document and between different documents and applications. A user selects an object and selects the “cut” command (from a menu or toolbar). This removes the object from…

cut scene

a brief presentation, usually a video, used between 2 interactive segments of a multimedia title, such as between 2 levels in a game.

CUU conference

Conference on Universal Usability, a conference that focuses on what it takes to make systems work for everyone, considering the wide diversity of people with different system configurations and from a wide variety of backgrounds, including international and disability issues.…

cyberchondria

the overuse & misuse of online health information; the tendency for some people to over-rely on online health resources and to pester their physician with concerns generated by the experience.

cycle button

a button used for selecting among a small number of options. Each time the button is pressed, the next option in the sequence is selected. A cycle button serves the same purpose as a radio button group but takes a…