Glossary » Design Principles

persuasive computing

or “captology”; the use of computing technology to change or influence attitudes or behaviors. Examples include advertising, public service messages, and demo and attract-mode screens used for point-of-sale displays and arcade games.

Many important ethical issues need to be considered…

pervasive usability

a principle of design that advocates the application of usability methods in every stage of the design process. Some of the primary stages of design, and some example usability techniques, are:

requirements gathering: field studies, interviews, focus groups requirements

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physical integration

when items that have to be compared are side by side on the screen so people can see both things simultaneously and not have to remember something from a previous page or have to scroll up or down to find…

playability

the degree to which a game is fun to play and usable, with an emphasis on the interaction style and plot-quality of the game; the quality of gameplay.

Playability is affected by the quality of the storyline, responsiveness, pace, usability,…

plug and play

a hardware architecture that enables users to add and remove input and output devices at any time and immediately use them, without software installation or complicated configuration. The computer system recognizes the devices and configures itself, as with the USB…

pointer jumping

when the pointer automatically moves around to the most likely place you’ll want to click next, such as moving the pointer over the default button of a dialog box as soon as the dialog appears. This shortens the average amount…

predictive metric

a value describing some aspect of a system that purports to provide a prediction or estimate of the usability of the system. For instance, if we described the font size used on a web page as a predictive metric (e.g.…

prisoner’s dilemma

a classic problem statement describing a situation where what is rational for an individual is in conflict with what is rational for the group (as with the commons problem). This type of problem is useful for describing problems in coordinating…

privacy

the principle of protecting private information about people, especially in shared or collaborative systems, and of helping to keep people free of distractions. Privacy may be provided for security reasons, to keep people (such as celebrities) from being deluged with…

productivity paradox

why is it that, despite adopting cool new technology, many businesses do not achieve higher productivity? That’s the productivity paradox. The systems were intended to improve productivity, but they didn’t. Why not? In general, it stems from a failure to…

progressive disclosure

the design principle that says to show overviews and hide details until the user requests more detail, and then to provide only the additional level of detail required.

This principle is often used in file systems and outlines, as with…

reaction time

a measure of a user’s delay in executing an action after being prompted. While it may measure “task time”, reaction time is usually used to refer to quick responses that do not require substantial mental processing (though the whole point…

readability

the degree to which the meaning of text is accessible, based on the complexity of sentences and the difficulty of the vocabulary that is used. Readability indexes usually rank usability by the age or grade level required for someone to…

reciprocity

a design principle that suggests that users of a communications system should be on equal terms, for instance, by allowing one person to see the video of another only if the other can also see the video of the first.…

redundant coding

or secondary coding; representing information in more than one way so that users have more than one opportunity to perceive and understand it, to reinforce the information, to make the information more accessible (because one representation may not work for…

redundant modalities

using more than one way to represent, display, and enter data, such as:

…

response time

time between receiving a stimulus and delivering an appropriate response or reaction. System response time is how long it takes the computer to respond to a user command, or the length of time, for instance, to download a web page…

responsiveness

the degree to which a user perceives a system as reacting quickly to user input. Responsiveness is not the same as speed. Slow systems can be perceived as highly responsive if they consistently provide quick feedback to users. This can…

reversible actions

any action that can be undone. Reversibility is a design principle that says people should be able to recover from their inevitable mistakes. Dialog boxes should have a Cancel button. Applications should have an Undo feature (and possibly multiple undo,…

role

a means of expressing that participants in a conversation come with different skills and interests and should have a user-interface that reflects their personal needs.

Roles such as chairperson, scribe, and facilitator reflect a set of access capabilities to shared…

RSVP

a mnemonic for requirements analysis – structural design – visual design – production, the main steps in a design process. In the spirit of iterative design, each stage would have an evaluation component to ensure that the design was proceeding…

SAFE

simplicity, appropriate form, function (workability & beauty), economy of effort. SAFE design principles were the organizing principle of the modern design book “art: an approach”, by Robert C. Niece, 1959.

safety

minimizing the risk of harm to people or the environment. Possible types of harm include physical harm (repetitive stress syndrome, electrocution), mental anguish (lack of privacy, negative self-attributions), and threats to property (fraud, vandalism).

Safe systems attempt to minimize both…

satisfaction

a common reference to the set of subjective responses a person has when using a system. Typically satisfaction is measured with questions that have their responses on Likert scales, e.g. “How satisfied are you with this software? (1=very dissatisfied, 7=very…

satisficing

a theory of human reasoning that says that people minimize cognitive load by minimizing reasoning and using quick heuristics to make decisions. Thus, people avoid complex memory, planning, and decision-making in favor of acting upon information immediately available perceptually, well-known…