This item is not the definitive copy. Please use the following citation when referencing this material: Dillon, A. (1987) Knowledge acquisition and conceptual models: a cognitive analysis of the interface. In: D. Diaper and R.Winder (eds.) People and Computers III. Cambridge: Cambridge University Press, 371-379. Abstract: Understanding how users process the information available to them through the computer interface can greatly enhance our abilities to design usable systems. This paper details the results of a longitudinal psychological experiment investigating the effect of interface style on user performance, knowledge acquisition and conceptual model development. Through the use of standard performance measures, interactive error scoring and protocol analysis techniques it becomes possible to identify crucial psychological factors in successful human computer use. Results indicate that a distinction between "deep" and "shallow" knowledge of system functioning can be drawn where both types of user appear to interact identically with the machine although significant differences in their respective knowledge exists. The effect of these differences on user ability to perform under stress and transfer to similar systems is noted. Implications for the design of usable systems are discussed.

This item is not the definitive copy. Please use the following citation when referencing this material: Dillon, A., Richardson, J. and McKnight, C. (1990) Navigation in Hypertext: a critical review of the concept. In D.Diaper, D.Gilmore, G.Cockton and B.Shackel (eds.) Human-Computer Interaction-INTERACT'90. North Holland: Amsterdam, 587-592. Abstract: With the advent of hypertext it has become widely accepted that the departure from the so-called "linear" structure of paper increases the likelihood of readers or users becoming lost. In this paper we will discuss this aspect of hypertext in terms of its validity, the lessons to be learned from the psychology of navigation and the applicability of the navigation metaphor to the hypertext domain.

This item is not the definitive copy. Please use the following citation when referencing this material: Dillon, A., Sweeney, M. and Maguire, M. (1993) A survey of usability evaluation practices and requirements in the European IT industry. In. J. Alty, S. Guest and D. Diaper (eds.) HCI'93. People and Computers VII. Cambridge: Cambridge University Press. Abstract: The present paper reports on a survey of current practices in usability engineering and requirements for support within European I.T. organisations. Responses were obtained from 84 individuals working in nine European countries. The data were analysed in terms of four themes: respondents' background, their interpretation and appreciation of the concept of usability, current practice with regard to usability evaluation, problems and requirements for support in conducting usability evaluation. Results suggest widespread awareness but only superficial application of Human Factors methods in Industry.

This item is not the definitive copy. Please use the following citation when referencing this material: Dillon, A., Sweeney, M., Herring, V., John, P. and Fallon, E. (1988) The psychology of designer style. The Alvey Conference 1988. DTI/IED Publications, 323-327. 1. INTRODUCTION: Underlying the notion of style is a basic premise that all designers are not the same and that the manner in which any designer tackles a problem and proposes a solution may be qualitatively different from other designers. If this is shown to be the case and the concept of designer style can be meaningfully discussed then any model of the process of design should allow for such variation at the level of the group or individual. This basically describes the starting point of the HUSAT team's investigation of the concept.

This item is not the definitive copy. Please use the following citation when referencing this material: Dillon, A. (1995) Artifacts as Theories: Convergence through User- Centered Design. 1995 Proceedings of the 58th Annual ASIS Conference, Medford NJ: ASIS, 208-210. Abstract: The present paper proposes the artifact as theory perspective which draws together models of scientific practice and design behaviour and in so doing, offers the view of any information technology system as a conjecture on the part of the design team of human and organizational requirements to be met. By adopting this perspective, information system design can be seen as an ill-structured problem best tackled by usercentered theories and methods. The present paper will outline this perspective, emphasizing the need for convergence of views at the outset of design, and demonstrate the advantages it offers to both the theory and practice of technology design and the field of information science.

This item is not the definitive copy. Please use the following citation when referencing this material: Dillon, A. and Morris, M. (1998) From "can they?" to "will they?": extending usability evaluation to address acceptance. AIS Conference Paper, Baltimore, August 1998. Introduction: usability engineering: Within the human-computer interaction (HCI) community, there exists a long and rich research paradigm on "usability engineering (UE)." Within the usability engineering tradition, usability is operationally defined as the effectiveness, efficiency and satisfaction with which specified users can perform particular tasks in a given environment (see e.g., Shackel 1991, Nielsen, 1993). Effectiveness answers: can users perform their tasks? Efficiency means: what resources do users expend to achieve a given outcome (e.g., time, effort)? Finally, satisfaction measures assess how well users like the application. From this perspective, usability is contextually defined in operational terms that designers can see as targets to meet, for example: "Users should be able to perform specified tasks with new tool after W minutes training, with X% effectiveness, at least Y% efficiency, and Z% greater satisfaction than with old interface" where W < infinity, and 0< [X, Y, Z] <100. The strengths of the usability engineering approach include: 1. The use of operationalised measures that are negotiated in context, 2. The direct coupling of usability to tasks the tool must support, 3. The capability of negotiated targets to fit into an iterative design process, and 4. The decoupling of the usability construct from interface features Each of these strengths gives the approach value to the software industry where design practices require targets to be met and where the success of a new tool is determined contextually rather than in any absolute manner. Thus, the usability engineering paradigm has enjoyed a wide range of support from industry. Nonetheless, there are associated weaknesses of this approach. Some of these weaknesses include: 1. Usability criteria are dynamic, not fixed, 2. Usability is thus contextually determined so what works in one context may not work in another and design practices must continually ground themselves in work practices 3. Determining usability criteria requires considerable analytic skill, 4. Generalization beyond context is difficult, 5. Criteria do not determine re-design advice While the approach advocated by usability engineers of deriving appropriate targets for design and testing to meet is useful, it is clear that usability does not fully determine actual system use (see Dillon and Morris 1996). Thus, it is possible that designers may produce a well engineered artifact that meets set criteria, but still fails to gain the acceptance of discretionary users. In other words, usability is a necessary but insufficient determinant of use.

This item is not the definitive copy. Please use the following citation when referencing this material: Dillon, A., Richardson, J. and McKnight, C. (1991) Institutionalizing Human Factors in the design process: the ADONIS Experience. Contemporary Ergonomics '91, London: Taylor and Francis, 421-426. Abstract: The ADONIS workstation was an experimental document delivery system developed to facilitate retrieval and printing of CD-ROM stored articles. Although primarily aimed at the document supply industry, its potential application in libraries and research environments with end users was recognised. Hence, the present authors were asked to assess the system ergonomically from this perspective, and the outcomes of this assessment form the basis of this paper. It was clear that the design of the system ignored many formal ergonomic considerations. Subsequent user evaluations of the interface highlighted several potentially serious problems and cast doubt on the usability of the system in the end-user domain. A follow-up study of actual usage rates during field-testing of the product confirmed the findings of the initial evaluation and also indicated that some of the very first design decisions (e.g., regarding the choice of journal titles included), which proved detrimental to the system's acceptance, might have been very different if human factors considerations had been taken into account. The present paper describes the system and the problems highlighted by the human factors practitioners as well as discussing the pitfalls that could have been avoided by earlier involvement. The potential role of human factors in early design of such products is emphasised.

This item is not the definitive copy. Please use the following citation when referencing this material: Richardson, J., Dillon, A., and McKnight, C. (1989) The effect of window size on reading and manipulating electronic text. In E. Megaw (ed.) Contemporary Ergonomics 1989. London:Taylor and Francis, 474-479. Abstract: With the advent of hypertext the presentation of electronic text is becoming an increasingly important issue. However, most research to date has focused on simplistic measures of reading speed or navigation in highly controlled presentation formats, often using very constrained texts and task scenarios. The present paper attempts a more meaningful analysis of the effect of window size on reader comprehension and manipulation of real-world texts. Reading a journal article for comprehension and a software manual for specific information are both investigated. Results indicate that screen size is not a major factor in performance on either task but readers express a strong preference for larger screens.

This item is not the definitive copy. Please use the following citation when referencing this material: Mostafa, J. and Dillon, A. (1996) Design and Evaluation of a User Interface Supporting Multiple Image Query Models. Proceedings of the 59th Annual Conference of the American Society for Information Science, Baltimore, MD, USA, October 21-26, 1996. I. Introduction: Digital image use occurs in many fields. For example, in the area of medicine, huge volumes of digital images are routinely generated for diagnostic purposes, sometimes reaching gigabyte range (Gitlin, 1992). Besser (1990) has designed highly innovative image- based selection systems to improve access to visual resources in architecture, anthropology and art collections. There are also signs that museums and archives have accepted the value of digital image technology in their environments (Besser, 1991; Wentz, 1989). Unfortunately, the technology for effective storage and retrieval of images has not kept pace with the technology of image production. The situation has reached such a critical stage that National Science Foundation (NSF) organized a special workshop on the topic of visual information management (Jain, 1993). The NSF workshop report stated, "It would be impossible to cope with this explosion of image information, unless the images were organized for retrieval. The fundamental problem is that images, video, and other similar data differ from numeric data and text data format, and hence they require a totally different technique of organization, indexing and query processing." This paper addresses the critical need for different techniques in improving retrieval of digital images. Our position is that the user interface is the principal component responsible for facilitating retrieval in databases. Therefore, to assure effective access design of interfaces need to be improved.

This item is not the definitive copy. Please use the following citation when referencing this material: Vaughan, M. and Dillon, A. (1998) The role of genre in shaping our understanding of digital documents. Proc. 61st Annual Meeting of the American Society for Information Science. Medford NJ: Information Today Inc., 559-566. Abstract: Interacting with documents in the digital domain is challenging many of our notions about discourse and its boundaries. Hyperlinked documents on the World Wide Web defy easy categorization and evaluation - making the role and value of digital documents difficult to assess. Most importantly, in such fluid and complex environments it is difficult to understand the nature of the interaction between users and information resources. This paper argues that notions such as navigation are limiting our understanding of these complex information spaces. Instead, what is needed is a broader framework of analysis that can embrace these concepts, and incorporate extended issues relating to shared understanding, relevance, and style. In the present paper we explore the utility of the intersection of genre theory and cognitive psychology in providing a meaningful framework for analysis and design purposes. In so doing we report the results of our latest research into the elements of genre that influence users of digital documents and provide examples of the usefulness of this analysis in web-based environments.