Alan F. Blackwell

Password memorability and security: empirical results

Users rarely choose passwords that are both hard to guess and easy to remember. To determine how to help users choose good passwords, the authors performed a controlled trial of the effects of giving users different kinds of advice. Some of their results challenge the established wisdom.

The state of the art in end-user software engineering

Most programs today are written not by professional software developers, but by people with expertise in other domains working towards goals for which they need computational support. For example, a teacher might write a grading spreadsheet to save time grading, or an interaction designer might use an interface builder to test some user interface design ideas. Although these end-user programmers may not have the same goals as professional developers, they do face many of the same software engineering challenges, including understanding their requirements, as well as making decisions about design, reuse, integration, testing, and debugging. This article summarizes and classifies research on these activities, defining the area of End-User Software Engineering (EUSE) and related terminology. The article then discusses empirical research about end-user software engineering activities and the technologies designed to support them. The article also addresses several crosscutting issues in the design of EUSE tools, including the roles of risk, reward, and domain complexity, and self-efficacy in the design of EUSE tools and the potential of educating users about software engineering principles.

Dasher—a data entry interface using continuous gestures and language models

Existing devices for communicating information to computers are bulky, slow to use, or unreliable. Dasher is a new interface incorporating language modelling and driven by continuous two-dimensional gestures, e.g. a mouse, touchscreen, or eye-tracker. Tests have shown that this device can be used to enter text at a rate of up to 34 words per minute, compared with typical ten-finger keyboard typing of 40-60 words per minute. Although the interface is slower than a conventional keyboard, it is small and simple, and could be used on personal data assistants and by motion-impaired computer users.

The reification of metaphor as a design tool

Despite causing many debates in human-computer interaction (HCI), the term “metaphor” remains a central element of design practice. This article investigates the history of ideas behind user-interface (UI) metaphor, not only technical developments, but also less familiar perspectives from education, philosophy, and the sociology of science. The historical analysis is complemented by a study of attitudes toward metaphor among HCI researchers 30 years later. Working from these two streams of evidence, we find new insights into the way that theories in HCI are related to interface design, and offer recommendations regarding approaches to future UI design research.

CHAPTER 5 – Notational Systems—The Cognitive Dimensions of Notations Framework

ion: types and availability of abstraction mechanisms. Abstractions (redefinitions) change the underlying notation. Macros, data structures, global findand-replace commands, quick-dial telephone codes, and word-processor styles are all abstractions. Some are persistent, some are transient. Abstractions, if the user is allowed to modify them, always require an abstraction manager -a redefinition sub-device. It will sometimes have its own notation and environment (e.g. the Word style sheet manager) but not always (for example, a class hierarchy can be built in a conventional text editor). Systems that allow many abstractions are potentially difficult to learn. Secondary notation: extra information in means other than formal syntax. Users often need to record things that have not been anticipated by the notation designer. Rather than anticipating every possible user requirement, many systems support secondary notations that can be used however the user likes. One example is comments in a programming language, another is the use of colours or format choices to indicate information additional to the content of text. Closeness of mapping: closeness of representation to domain. How closely related is the notation to the result it is describing?

Graphic elicitation: using research diagrams as interview stimuli

Diagrams are effective instruments of thought and a valuable tool in conveying those thoughts to others. As such, they can be usefully employed as representations of a research domain and act as stimulus materials in interviews. This process of graphic elicitation may encourage contributions from interviewees that are difficult to obtain by other means. By representing concepts and relationships that other visual artefacts cannot depict, diagrams provide a complementary addition to conventional interview stimuli. This article discusses the application of graphic elicitation within the broader context of the diagramming process. Consideration is given to the unique characteristics of diagrams and the ways in which they are interpreted. Thus, the specific benefits that diagrams offer as interview stimuli may be understood. Following this, an example study is described in which the graphic elicitation process was employed in interviews with industrial designers. Reporting on a study in which the interviewees possessed a well-developed graphic sensibility allows a broad range of graphic elicitation’s potential benefits to be illustrated. In closing the article, a discussion is held on the range of methodological issues that must be addressed when employing diagrams in a research study.

Cognitive Dimensions of Notations: Design Tools for Cognitive Technology

The Cognitive Dimensions of Notations framework has been created to assist the designers of notational systems and information artifacts to evaluate their designs with respect to the impact that they will have on the users of those designs. The framework emphasizes the design choices available to such designers, including characterization of the users activity, and the inevitable tradeoffs that will occur between potential design options. The resuliing framework has been under development for over 10 years, and now has an active community of researchers devoted to it. This paper first introduces Cognitive Dimensions. It then summarizes the current activity, especially the results of a one-day workshop devoted to Cognitive Dimensions in December 2000, and reviews the ways in which it applies to the field of Cognitive Technology.

AutoHAN: an architecture for programming the home

AutoHAN is a networking and software architecture that enables user programmable specification of the interaction between appliances in a domestic house. This concept represents an immense challenge for End-User Programming. The characteristics of the potential user population are far broader than any other population of end-user programmers. It is therefore essential to approach the design of the programming environment from a well founded perspective of cognitive ergonomics and user modelling. We have created a novel programming language, Media Cubes, which is aimed at the same user population as existing domestic remote controls. Moreover, we have applied a cognitive model of programming behaviour in order to specify a language that gives the advantages of direct manipulation as well as the power of more conventional languages.

Smartback: supporting users in back navigation

This paper presents the design and user evaluation of SmartBack, a feature that complements the standard Back button by enabling users to jump directly to key pages in their navigation session, making common navigation activities more efficient. Defining key pages was informed by the findings of a user study that involved detailed monitoring of Web usage and analysis of Web browsing in terms of navigation trails. The pages accessible through SmartBack are determined automatically based on the structure of the users navigation trails or page association with specific users activities, such as search or browsing bookmarked sites. We discuss implementation decisions and present results of a usability study in which we deployed the SmartBack prototype and monitored usage for a month in both corporate and home settings. The results show that the feature brings qualitative improvement to the browsing experience of individuals who use it.

Mental imagery in program design and visual programming

There is widespread anecdotal evidence that expert programmers make use of visual mental images when they are designing programs. This evidence is used to justify the use of diagrams and visual programming languages during software design. This paper reports the results of two studies. In the first, expert programmers were directly questioned regarding the nature of their mental representations while they were engaged in a design task. This investigative technique was used with the explicit intention of eliciting introspective reports of mental imagery. In the second, users of a visual programming language responded to a questionnaire in which they were asked about cognitive processes. The resulting transcripts displayed a considerable number of common elements. These suggests that software design shares many characteristics of more concrete design disciplines. The reports from participants in the two studies, together with previous research into imagery use, indicate potential techniques for further investigation of software development support tools and design strategies.