action plan: a sequence of actions selected to achieve a goal.
activities: the collective ventures which provide context and meaning for people’s interactions with computers and other tools
activity design: the first phase of reasoning about a new software system, in which the problems and opportunities of current practice are transformed into new ways of behaving
affective computing: the study and design of user interfaces that explicitly engage and respond to people’s emotions or affective experiences
affordance: perceptual characteristics of an object that make it obvious what the object can do and how it can be manipulated
analytic evaluation: usability evaluation based on a careful analysis or theoretical modeling of user interface features, usually carried out by usability experts
anthropomorphism: considering machines (especially computers) as if they have human capabilities or responsibilities
articulatory directness: the extent to which the physical behaviors carried out with a user interface map to the goals and intentions of the user’s current task
artifact: a designed object or tool used in support of an activity
articulation work: the collaborative effort required to document, exchange, schedule, refine, and otherwise coordinate shared activities
assistance policy: a predetemined set of rules that usablility evaluators develop and apply to decide when and how to intervene during a usability test
asynchronous collaboration: computer-mediated shared activity that does not take place in real time (see synchronous collaboration)
augmented reality: distributing computational power among objects in the real world; the new capability may be achieved by embedding input sensors or other processors, or by attaching information that is processed by external computational devices
avatar: an icon or other visual depiction used to represent the user in an information display
balloon help: a technique for embedding documentation in the user interface; when balloon help is turned on, a small “balloon” containing descriptive information appears when the mouse pointer moves over a display object
baseline: task performance or other usability outcomes that are measured under normal conditions and then used as a basis for comparison to other conditions
benchmark task: a standard task that is used to comparatively evaluate designs, measuring users' performance on the task with different versions or systems
between-subjects design: a usability test structure in which a separate group of participants is exposed to each level of an independent variable
breadth (of a hierarchy): the average number of choices at any level in a hierarchical information structure
breakdown: an episode of interaction in which a system does not work in the real world as planned or expected
categorical variable: user choices or other measures that can be classified and tabulated but not converted to a numeric value
change score: a difference between two numerical measures gathered from the same participant, one measured before a usage experience takes place, and one afterwards
chauffered prototype: a user interface prototype that is not used directly by a test user, but instead is used by a designer under the user’s direction
chord keyboard: an input device in which alphanumeric information is entered by conjointly pressing groups of keys
chunk: a structured collection of information that acts as a single unit with respect to storage and information processing capacity
claims analysis: an analytic evaluation method involving the identification of scenario features that have significant positive and negative usability consequences
claims feature: an element of a situation or an interactive system that has positive or negative consequences for people in this or similar situations
closure: a Gestalt perceptual principle stating that a perceivers are likely to fill in small gaps in a figure in order to see it as complete (and thus more simple)
cognitive walkthrough: an expert critique of a user interface that involves simulating the use of a system and analyzing possible problems in goal selection, planning, or action execution
command language: a structured set of expressions that a computer interprets as requests for information and services
common ground: mutual expectations of communication partners that help them predict and interpret what is said
content analysis: a summarization and interpretation method in which qualitative data like behavioral observations or user comments are grouped by similarity and labeled
context-aware computing: computer functionality and user interaction options that are selected and presented as a function of what is known about the use setting
contextual inquiry: a method used in requirements analysis and formative evaluation, in which people are observed as they carry out their normal tasks, and questioned about interesting or confusing episodes
continuity: a Gestalt perceptual principle stating that objects positioned along a smooth curve are more likely to be seen as a group
conversational agents: software agents that are interact with the user using natural language and that are often given a human-like appearance
confound: a problem in experimental design in which two variables are correlated, making the interpretation of observed effects ambiguous
cooperative design: a variant of user-centered design that emphasizes
the direct involvement of users in analysis and design activities (also called
participatory design)
critical incident: an event reported by a user as having a significant effect, either positive or negative, on task performance or satisfaction
critical subtasks: the key features of a scenario that are expected to influence usability, and thus are carefully specified and evaluated continuingly during iterative design
data collection form: a planning and observation form designed to guide the evaluators’ note-taking, time measurement, and so on, during a usability test
debriefing: a planned interaction after a user test, in which the test participant is allowed to ask and receive answer to questions about the system, tasks, or goals of the study
default (in a user interface): a pre-set input string or other user input that is offered as a likely input value; users can simply accept this input rather than generating their own
demonstration: a documentation technique in which a sequence of user inputs and system responses are animated, so that the user can see what actions to perform and what system response to expect in return
dependent variable: a usability outcome that is measured to determine if there are effects of system variations or other test characteristics (see independent variable)
depth (of a hierarchy): the average number of intermediate nodes between the root of a hierarchical information structure a terminating node
design rationale: arguments for why (or why not) a feature or set of features should be incorporated into a design
designer’s model: the mental representation of a design held by a designer, sometimes shared via design documentation like scenarios or feature lists
dialog design: the specification of each step of user input and system response during a user interaction sequence
digital divide: the gap in opportunities for education, jobs, and wealth, between those who have and use computers, and those who do not
direct manipulation: a user interface style in which system objects are represented visually and can be manipulated in ways analogous to how objects are manipulated in the real world (e.g., pointing, grabbing, dragging)
distributed cognition: a framework analyzing how information and processing activitiy is distributed throughout a situation—across the mental states of collaborating individuals, their communications with each other, and the states of task-relevant artifacts and tools
electronic brainstorming: a computer-mediated discussion in which participants are able to contribute ideas freely and in parallel, often anonymously so as to minimize social inhibitions
ethnography: in-depth study of individuals and groups, their practices, and their artifacts, in the context of their normal work environment
empirical evaluation: usability evaluation based on collection of data from users working with an interactive system or prototype
evolutionary development: an approach to system development in which a version of the system is created as early as possible and then expanded or refined in an incremental fashion as more system requirements and constraints are discovered
external consistency: the use of similar (or identical) interface actions and objects in a system for similar task actions and objects encountered in other systems or in the real world
FAQs (Frequently Asked Questions): questions about a system that are asked and answered multiple times are collected and made easily accessible to all users
feedback: information generated and communicated by a computer system in response to input from the user; typically it is provided to guide or confirm task-relevant behavior
field study: a usability evaluation of an installed system carried out in a workplace context, often involving surveys or observational methods
fisheye view: a visualization in which one part of an information structure is presented in detail relative to the surrounding context
Fitts' Law: time to point to a target is proportional to the distance from the target divided by the width of the target
floor control: the mechanism by which users take and relinquish input control in a shared work system
focus + context: a visualization in which one part of an information structure is presented in detail relative to the surrounding context
formative evaluation: usability analyses carried out during system development with the goal of identifying usability problems and guiding redesign
Gestalt principles: principles of human perception that emphasize wholistic relationships among visual features that identify objects and configurations
glyph: a visual symbol or code that is attached to a physical object, to be recognized by a computer as task-relevant input
grammar: composition rules that describe how commands or other language elements can be combined to form syntactically correct expressions
GOMS analyis: an analytic evaluation method that involves describing users’ goals, operators, methods, and selection rules for computer tasks
grid-based design: an information design strategy in which a grid is defined to specify the physical scale of visual elements, their relative position, and axes of symmetry
Gulf of Evaluation: the psychological distance between what is displayed by a computer and the user’s understanding of how it relates to current task goals
Gulf of Execution: the psychological distance between the task goals of a user and the actions required to achieve these goals with a computer system
haptic feedback: kinesthetic or force feedback provided by a user interface, often to convey physical characteristics of computational objects and media
heuristic evaluation: a user interface critiquing process carried out by experts with usability guidelines
hierarchical task analysis: decomposition of a complex task into a structure of constituent subtasks, annotated with the logic needed to perform the subtasks at each level
hierarchy: an information structure in which a root concept is successively decomposed, such that every child concept is the descendent of one and one only parent concept
horizontal prototype: a user interface prototype that illustrates all or most of a software system at a high level but provides little if any details about the functionality or user interaction
human-computer interaction: situations in which people understand and make requests of a software system, and the system interprets and responds to these requests
human factors: the study of variables that influence human performance in work contexts
hypothesis: a prediction of a causal relation between one or more independent variables and one or more dependent variables
hypothetical stakeholders: imaginary persons with characteristics that are typical of a stakeholder group, developed to serve as actors in analysis and design scenarios
immersive environment: a virtual reality simulation in which the user wears special headgear, eyeglasses, or other input devices so that the simulated world is experienced as a three-dimensional space
independent variable: an
attribute of a usability test situation that is manipulated to determine if it
influences outcome measures (see dependent variable)
information design: presentation and organization of task objects and actions in a way that facilitates the user’s perception, interpretation, and understanding
information layering: a documentation technique wherein help information is organized into successively more detailed levels accessed on an as-needed basis
information model: a set of concepts, relationships, and representations that are developed to help users make sense of large data sets and complex functionality
information visualization: a representational technique in which properties of data are mapped to visual features and rendered as a spatial display
informed consent: participants in usability studies must be informed in advance of the procedures and risks, and must feel free to withdraw from the study at any time
inheritance: a technique used in object-oriented programming to share attributes and behavior among related classes; superclasses specify common behaviors, and subclasses extend the superclasses with specialized attributes or behaviors
intelligent tutoring system: an online training system that models user knowledge and progress through pre-analyzed learning tasks, and uses this model to make suggestions, correct errors, answer questions, or provide other learning support
interaction design: mechanisms for accessing and manipulating the elements of an information design to facilitate the user’s goal selection, action planning, and action execution
interactive tutorial: an online series of presentations and exercises designed to introduce and practice system concepts and skills
interference (in memory): when information learned earlier causes difficulty in learning or errors in remembering new information
internal consistency: the use of similar (or identical) interface actions and objects within a system to represent similar task actions and objects.
interpretation (of an information display): the process of recognizing how perceived information is related to the objects and actions provided by a user interface
interval variable: data measured on a scale for which any two contiguous values are equi-distant
inquiry method: an analysis method where the goal is to raise questions and prompt discussion that will lead to a richer understanding of a problem
iterative design: a cyclical approach in which design ideas are prototyped and tested, with the results used to guide the next cycle of re-design
iterative development: an approach to software development in which the design specification is continually modified through prototyping and testing activities
keyboard short-cut: a brief sequence of keypresses that is assigned to, and can be substituted for, a graphical user interaction sequence
knowledge management: the activity of identifying, documenting, archiving, maintaining, and reusing the concepts and skills developed by the members of an organization
knowledge work: work involving significant expertise and intellectual decision-making
layout appropriateness: a design heuristic in which interface controls (e.g., a button in a dialog box) are laid out to optimize travel time for the most common usage cases
learn by doing: a strategy exhibited by many learners (especially those with task-domain or computer experience) in which they try to accomplish tasks as they learn
level (of a variable): one of multiple possible values of an experimental variable used in a usability test; the levels of independent variables form the experimental conditions
Likert scale: a rating scale used to gather subjective judgements, where an assertion about the task or system is made, and users rate the level of their agreement
localization: a design strategy in which global interaction and exchange is supported by adapting information and user interface designs to particular regions and cultures
locus of control: users' sense of how a dialog is being controlled, in particular by them or by the computer
longitudinal study: ranalysis of one or more user behaviors or attitudes over an extended period of time, often in a real world usage setting
macro: a user-defined sequence of events that is stored, labeled, and subsequently executed as a single command
mediated evaluation: an empirical usability evaluation in which the content and structure of the usability test materials are guided by a prior analytic evaluation
mental model: a cognitive structure of concepts and procedures that users refer to when selecting relevant goals, choosing and executing appropriate actions, and understanding what happens when they interact with a computer system (or other tool)
metaphor: a known concept that is used to understand a new concept by analogy
minimalism: an approach to instruction and documentation that emphasizes realistic tasks, minimal verbiage, thinking and improvization by the user, and the recognition and recovery from errors
mistake: when an inappropriate system goal is selected and pursued
mixed design: a usability test structure in which the independent variables are manipulated in a combination of within-subjects and between-subjects conditions
mobile computing: use of computing systems outside normal office or work environments, particularly while moving around in the physical world
mode (of a user interface): a user interface state that provides a special context for interpretation of user input, including ignoring some input
MOO (Multi-user Domain Object-Oriented): a MUD where the characters, their behavior, and all other services are built and extended using an object-oriented programming language
MUD (Multi-user Domain): a persistent collaborative environment that is modeled on a geographic space
multimodal user interface: user interaction that integrates multiple input and output channels, either in parallel or in sequence
multiple coordinated views: a visualization technique in which complementary views of an underlying information structure are presented, manipulated, and updated simultaneously (see also tiled display)
multiple overlapping windows: a user interface technique in which parallel tasks are presented and pursued in different windows open simultaneously; the layering of windows mirrors the activity history of each task
newsgroup: an online threaded discussion where people post positions, questions, comments, or answers
nonfunctional requirements: qualities of a system under development that are not directly related to its function, for example maintainability or reliability
nonverbal communication: the body language, facial expressions, gestures, and other non-language cues that extend and aid interpretation of normal conversations
operationalize: to specify how a variable of interest will be manipulated or measured
opportunistic behavior: the tendency for users to generate and pursue goals suggested by manifest elements of the user interface
ordinal variable: data measured on a scale that has an inherent linear sequence or order
participatory analysis: a phase of cooperative or participatory design where users are presented with records of their own or other users’ behavior, and asked to reflect on features of interest
participatory design: a variant of user-centered design that emphasizes the direct involvement of users in analysis and design activities (also called cooperative design)
pilot test: a small study carried out prior to a large-scale study in order to practice and refine usability test materials, procedures, or data collection technique
PICTIVE: Plastic Interface for Technology Initiatives through Video Exploration, a participatory design technique addressing user interface layout
pluralistic walkthrough: a variant of a usability inspection where usability engineers, designers, and end users collaboratively step through and critique a user interface
point-of-view: a technique used during the design of interactive systems in which the designer adopts a computational perspective on the task objects in a scenario.
pragmatics (of a user interaction device): the physical behaviors that are required to manipulate the input or output devices in a user interface
presence (in a simulated world): the extent to which users of a virtual reality system feel as if they are moving within and experiencing the simulated environment
problem scenario: a story of current practice developed to reveal aspects of the stakeholders and their activities that have implications for design
production paradox: many users are highly motivated to continually accomplish real results, and as a result are often unwilling to take time to learn how to best achieve any given result
property sheet: a secondary window activated to present and manipulate the attributes of task objects or user interface controls
prototype: an operational model of a design or software development proposal, usually created for testing and feedback purposes
proximity: a Gestalt perceptual principle stating that objects positioned near one another are more likely to be seen as comprising a group
proxy server: an intermediate server that intercepts and assists in processing the requests sent by a client to a server on a network; the technique is often used to improve the quality or latency of a server’s response
radar view: an overview of a shared workspace that includes an outline or other indication of the portion of the workspace that is being viewed by each collaborator
random assignment: test participants are allocated to test conditions on a random basis
redundant coding: multiple perceptual cues signal the same information
remote usability evaluation: collection of usability problem reports by users in the course of their actual work with a computer system
requirements analysis: the detailed study of stakeholders and their current situation that is used to identify problems and opportunities to be addressed by a new system
requirements specification: a document listing and describing the features that a system under development is expected to provide
retrospective interview: a user interview conducted soon after a task has been completed to determine what usability issues stand out in a user’s memory of the interaction; sometimes the user’s memory may be prompted with a videotape or other records of activity
roomware: furniture or other objects in a room that have been augmented with computational powers designed to be useful for the activities conducted in the room
root concept: a multi-faceted description of the starting premises of a design project that includes a high-level vision, basic rationale, stakeholders, and starting assumptions
scaffolding: an instructional technique in which people are given support of some kind (often tool-based) that allows them to carry out, and thereby learn about, tasks that they otherwise would be unable to do
scenario: a narrative or story that describes the activities of one or more persons, including information about goals, expectations, actions, and reactions
scenario mock-up: one or more screen designs or other physical artifacts, created to illustrate key system states described by a scenario
scenario machine: a special-purpose user interface prototype that can be used to enact a user interaction scenario, in other words a single thread of execution given a starting state
self-instruction: an approach in which people learn on their own using standalone documentation, tutorials, and tools
self-reflection: a usability evaluation method in which users are asked to remember and reflect about their own goals, plans, behaviors, and reactions
semantic filtering: a dynamic information visualization technique in which the semantic attributes of each data point are used to determine whether the element is visible, and where and how it is rendered if visible
semantic directness: the extent to which a user interface allows users to pursue their goals in a direct fashion
severity (of a usability problem): a judgement about how much impact an observed or analyzed usability problem will have on actual use
similarity: a Gestalt perceptual principle stating that objects that look alike are more likely to be perceived as comprising a group
site map: an overview of a large information space (typically a Web site) that may be of a textual form (e.g., a table of contents), a diagram, or an image
slip: an error that occurs during action planning or execution when an appropriate system goal was selected
social computing: the study and design of user interfaces that explicitly engage and respond to people’s social expectations
social context: the personal and organizational relationsihps among people in a situation, including their roles, and their knowledge of one another’s history, goals, and preferences
sociotechnical systems theory: an approach to software development in which the information technology system and the surrounding organization are analyzed, designed, and iterated as a single co-evolving system.
software agent: a computational entity that observes users’ behavior, make inferences about their goals and needs, and offers suggestions or other helpful advice
software crisis: the failure of the software industry to keep up with the demand for systems and applications of greated complexity, reflected in cost overruns, late delivery, and ineffective and unreliable systems
software logging: instrumentation of a system such that it automatically records and time-stamps user actions and system reactions
squint test: an assessment of a display’s “gestalt” made by squinting the eyes to blur the visual details of a display and allow the layout of major structures to stand out.
stakeholder: any individual or organization with an interest in the process or product of an analysis or design project
stakeholder profile: a summary of the general characteristics of a stakeholder group, including their background, expectations, and technology preferences
stakeholder diagram: a sketch of major stakeholders with interconnections indicating the relations and dependencies among the different groups
storefront testing: a usability evaluation method in which a prototype of an interactive system is placed in a hallway or other public area so that people passing by can try out the system and provide feedback
storyboard: a graphical event-by-event enactment of all or part of a scenario, developed to communicate or analyze a user interface design; the enactment may be at a high level (e.g., major screen changes) or at a detailed level (e.g., mouse selections), depending on the usability issue being explored
subjective reactions: a user’s personal responses, judgements, or opinions before, during, or after interaction with a computer system
summative evaluation: usability analyses carried out at milestones during system development with the goal of assessing whether and how well a system has met its usability objectives
symmetry: a Gestalt perceptual principle stating that similar or identical objects seen on either side of a possible axis of rotation are more likely to be seen as a group
system goal: a task-related goal expressed in terms of the objects and actions offered by a software system
synchronous collaboration: computer-mediated communication or shared work that takes place in real time (see asynchronous collaboration)
system functionality: the information a system holds or accesses, the kinds of operations that are permitted on this information, and the results that are returned by these operations
systematic documentation: an approach to user documentation that analyzes knowledge about a system into hierarchies, and then systematically introduces and builds up component skills and concepts one-by-one
tacit knowledge: knowledge that people have in an inarticulate form, which they may not be able to produce or explain on demand, but which they can enact, for example know-how about exceptions that arise in a work setting
technological determinism: the view that technology is the single most important factor in determining the success of an organization
think-aloud protocol: a usability evaluation method in which the user speaks out loud his or her goals, plans, behaviors, and reactions while using an interactive system
tiled display: a user interface style in which parallel tasks or subtasks are presented in separate windows that are sized and arranged to prevent overlapping (see also multiple coordinated views)
tooltips: a method for embedding small snippets of documentation in a user interface; usually a brief statement of a display object’s name or function appears when the pointer rests over it
top-down processing: the impacts that a person’s expectations and the task context have on the perception, recognition, and interpretation of information
tradeoff: an issue (often in design) that is understood to have competing arguments, usually contrasting positive and negative impacts of an option
training wheels: an approach to user training that involves temporary deactivation (but not hiding) of functionality deemed unnecessary or inappropriate for use by novices
transfer of learning: a learning and memory phenomenon in which what is learned in one situation facilitates understanding and behavior in a similar situation.
ubiquitous computing: a term used to refer to the increasingly pervasive availability of computational processing in the world around us
user model: a representation (typically computer-based) of the knowledge and mental activities involved in use of a computer system, often used to make predictions about system usability
usability: the quality of an interactive computer system with respect to ease of learning, ease of use, and user satisfaction
usability engineering: an approach to software development in which target levels of system usability are specified in advance, and the system is engineered toward these measures
usability evaluation: any activity, either analytic or empirical, directed at assessing or understanding the usability of an interactive system or prototype
usability inspection: an
analytic method in which usability experts examine the user interaction
required to perform central or critical tasks with an interactive system or
prototype, looking for problematic aspects of user input or system response
usability laboratory: one or more rooms designed to simulate office or other computer use settings, usually instrumented with software and hardware for capturing the user’s behavior as he or she works through a set of tasks
usability specifications: critical or typical user tasks that are decomposed into subtasks, associated with target usability outcomes, and iteratively evaluated to guide redesign work.
use case: an enumeration of the complete course of events that can take place in response to some user input; the case specifies all possible interactions between the user and the system
user background survey: a questionnaire (usually brief) completed by a usability test participant prior to interaction with a system or prototype (sometimes called a pre-test)
user documentation: stored training and help information provided to assist users in carrying out activities with a computer system
user reaction survey: a questionnaire completed by a usability test participant during or after interaction with a system or prototype (sometimes called a post-test)
user interface: the physical representations and procedures that are provided for viewing and interacting with the system functionality.
user interface prototype: an operational version or mock-up of a system that supports interaction between the user and the system that is used for user testing and iterative design
user-system conversation: a scenario-based analysis technique in which user input is specified as one side of a conversation and the system’s interpretation, processing, and response to this input is specified on the other
validity (of a usability evaluation): the extent to which the conditions of an evaluation (users, setting, tasks) are representative of real world use
variability (of usability test data): the amount of diversity in a sample of data; high variability makes it more difficult to detect and interpret differences among test conditions
veridicality (of virtual reality): the extent to which a simulated world matches the structures, information, and actions possible in the real world
vertical prototype: a user interface prototype that illustrates all of a system’s functionality and user interface but for just one or a small set of tasks
visual design program: a set of visual design features and relationships that are deliberately repeated to create consistency and coherence among screens, dialog boxes, and other user interface elements
visual language: the features of an information design (e.g., menu style, font type and size, button shape and size) that are repeated across visual displays to create a sense of consistency and coherence
walk-up-and-use system: a computer system that requires no explicit user training; the functionality and user interaction procedures are designed to be self-evident and intuitive
waterfall: an approach to software development that organizes activities into a series of modular phases, beginning with the analysis of functional requirements, and continuing through software design, implementation, testing, and maintenance
white space: the parts of a graphical display that contain no graphical elements
widget: a user interface control (e.g., a menu or scroll bar), often predefined by the windowing system used to build a user interface
WIMP (Windows, Icons, Menus, Pointer): the graphical user interface style popularized by the Xerox Star and the Apple Macintosh in the 1980’s
within-subjects design: a usability test structure in which the same subjects are exposed to different levels of an independent variable (also called repeated measures)
wizard (help documentation): online assistance wherein a computer system recognizes that the user is attempting a specific task, and offers step-by-step guidance through the procedure
Wizard of Oz (prototype): a software system simulation, in which someone hides behind the scenes to interpret and generate meaningful responses to a user’s input
workflow system: a business support system that operates on an explicit model of task procedures; this model is used to plan, coordinate, and track interrelated tasks
workplace themes: labeled categories used to group related observations, stakeholder comments, or other data collected in a field study