Short Version
Conceptions of the Discipline of HCI: Craft, Applied Science, and Engineering
John Long and John Dowell
Ergonomics Unit, University College London, 26 Bedford Way, London. WC1H 0AP. L.
Published in: People and Computers V. Sutcliffe A. and Macaulay (ed.s). Cambridge University Press, Cambridge. Proceedings of the Fifth Conference of the BCS HCI SIG, Nottingham 5-8 September 1989.
……..First, consideration of disciplines in general suggests their complete definition can be summarised as: ‘knowledge, practices and a general problem having a particular scope, where knowledge supports practices seeking solutions to the general problem’……….
Contents 1. Introduction 2. A Framework for Conceptions of the HCI Discipline 3. Three Conceptions of the Discipline of HCI 4. Summary and Conclusions
1. Introduction
The main theme of HCI ’89 is ‘the theory and practice of HCI’. …….. For example, what is HCI? What is HCI practice? What theory supports HCI practice? How well does HCI theory support HCI practice? 1.1. Alternative Interpretations of the Theme …….. Some would claim HCI theory as explanatory laws, others as design principles. Some would claim HCI theory as directly supporting HCI practice, others as indirectly providing support. Some would claim HCI theory as effectively supporting HCI practice, whilst others may claim such support as non-existent. …….. Answers to different questions may also be mutually exclusive; for example, HCI as engineering would likely exclude HCI theory as explanatory laws, and HCI practice as ‘trial and error’. And moreover, answers to some questions may constrain the answers to other questions; for example, types of HCI theory, perhaps design principles, may constrain the type of practice, perhaps as ‘specify and implement’.
1.2. Alternative Conceptions of HCI: the Requirement for a Framework
1.3. Aims .
2. A Framework for Conceptions of the HCI Discipline
2.1. On the Nature of Disciplines Most definitions assume three primary characteristics of disciplines: knowledge; practice; and a general problem. All definitions of disciplines make reference to discipline knowledge as the product of research or more generally of a field of study. Knowledge can be public (ultimately formal) or private (ultimately experiential). It may assume a number of forms; for example, it may be tacit, formal, experiential, codified – as in theories, laws and principles etc. It may also be maintained in a number of ways; for example, it may be expressed in journals, or learning systems, or it may only be embodied in procedures and tools. All disciplines would appear to have knowledge as a component (for example, scientific discipline knowledge, engineering discipline knowledge, medical discipline knowledge, etc). Knowledge, therefore, is a necessary characteristic of a discipline. …….. suggest the definition of a discipline as: ‘the use of knowledge to support practices seeking solutions to a general problem having a particular scope’.
2.2. Of Humans Interacting with Computers
2.3. The Framework for Conceptions of the HCI Discipline Hence, we may express a framework for conceptions of the discipline of HCI as: ‘the use of HCI knowledge to support practices seeking solutions to the general problem of HCI of designing humans and computers interacting to perform work effectively’.
3. Three Conceptions of the Discipline of HCI
3.1. Conception of HCI as a Craft Discipline Craft disciplines solve the general problems they address by practices of implementation and evaluation. Their practices are supported by knowledge typically in the form of heuristics; heuristics are implicit (as in the procedures of good practice) and informal (as in the advice provided by one craftsperson to another). Craft knowledge is acquired by practice and example, and so is experiential; it is neither explicit nor formal. ……..HCI craft knowledge, supporting practice, is maintained by practice itself. ……..
The first explanation of this – and one that may at first appear paradoxical – is that the (public) knowledge possessed by HCI as a craft discipline is not operational. That is to say, because it is either implicit or informal, it cannot be directly applied by those who are not associated with the generation of the heuristics or exposed to their use. If the heuristics are implicit in practice, they can be applied by others only by means of example practice. If the heuristics are informal, they can be applied only with the help of guidance from a successful practitioner (or by additional, but unvalidated, reasoning by the user). ……..If craft knowledge is not operational, then it is unlikely to be testable –……..there is no guarantee that practice applying HCI craft knowledge will have the consequences intended (guarantees cannot be provided if testing is precluded). There is no guarantee that its application to designing humans and computers interacting will result in their performing work effectively……….
Thus, with respect to the guarantee that knowledge applied by practice will solve the general HCI problem, the HCI craft discipline fails to be effective. If craft knowledge is not testable, then neither is it likely to be generalisable ……To be clear, if being operational demands that (public) discipline knowledge can be directly applied by others than those who generated the knowledge, then being general demands that the knowledge be guaranteed to be appropriate in instances other than those in which it was generated. Yet, the knowledge possessed by HCI as a craft discipline applies only to those problems already addressed by its practice, that is, in the instances in which it was generated. ……..
Thus, with respect to the generality of its knowledge, the HCI craft discipline fails to be effective. It (Craft) is ineffective because its knowledge is neither operational (except in practice itself), nor generalisable, nor guaranteed to achieve its intended effect – except as the continued success of its practice and its continued use by successful craftspeople.
3.2. Conception of HCI as an Applied Science Discipline The discipline of science uses scientific knowledge (in the form of theories, models, laws, truth propositions, hypotheses, etc.) to support the scientific practice ……..Scientific knowledge is explicit and formal, operational, testable and generalisable. It is therefore refutable (if not proveable; Popper [1959]). An applied science discipline is one which recruits scientific knowledge to the practice of solving its general problem – a design problem. HCI as an applied science discipline uses scientific knowledge as an aid to addressing the general problem of designing humans and computers interacting to perform work effectively. …….
First, its science knowledge cannot be applied directly, not – as in the case of craft knowledge – because it is implicit or informal, but because the knowledge is not prescriptive; it is only explanatory and predictive. Its scope is not that of the general problem of design. Second, the guidelines based on the science knowledge, which are not predictive but prescriptive, are not defined, operationalised, tested or generalised with respect to desired effective performance. Their selection and application in any system would be a matter of heuristics (and so paradoxically of good practice). Third, the application of guidelines based on science knowledge does not guarantee the consequences intended, that is effective performance…….
HCI as an applied science discipline, however, differs in two important respects from HCI as a craft discipline. Science knowledge is explicit and formal, and so supports reasoning about the derivation of guidelines, their solution and application (although one might have to be a discipline specialist so to do). Second, science knowledge (of encoding specificity, for example) would be expected to be more correct, coherent and complete than ……..It (Applied Science) fails to be effective principally because its knowledge is not directly applicable and because the guidelines based on its knowledge are neither generalisable, nor guaranteed to achieve their intended effect.
3.3. Conception of HCI as an Engineering Discipline The discipline of engineering may characteristically solve its general problem (of design) by the specification of designs before their implementation. It is able to do so because of the prescriptive nature of its discipline knowledge supporting those practices – knowledge formulated as engineering principles. Further, its practices are characterised by their aim of ‘design for performance’.
Engineering principles may enable designs to be prescriptively specified for artefacts, or systems which when implemented, demonstrate a prescribed and assured performance. ……. The conception of HCI engineering principles assumes the possibility of a codified, general and testable formulation of HCI discipline knowledge which might be prescriptively applied to designing humans and computers interacting to perform work effectively. Such principles would be unequivocally formal and operational. Indeed their operational capability would derive directly from their formality, including the formality of their concepts –…….
…….. The abstracted form of those principles is visible. An HF engineering principle would take as input a performance requirement of the interactive worksystem, and a specified behaviour of the computer, and prescribe the necessary interacting behaviours ……..
First, HCI engineering principles would be a generaliseable knowledge. Hence, application of principles to solving each new design problem could be direct and efficient with regard to costs incurred. The discipline would be effective. Second, engineering HCI principles would be operational, and so their application would be specifiable…….. Because they would be operational, they would be testable and their reliability and generality could be specified.
4. Summary and Conclusions This paper has developed the Conference theme of ‘the theory and practice of HCI’. ……..
Although all conceptions of HCI as a discipline necessarily include the notion of practice (albeit of different types), the concept of theory is more readily associated with HCI as an applied science discipline, because scientific knowledge in its most correct, coherent and complete form is typically expressed as theories.
Craft knowledge is more typically expressed as heuristics. Engineering knowledge is more typically expressed as principles. ……. Although all three conceptions address the general problem of HCI, they differ concerning the knowledge recruited to solve the problem. Craft recruits heuristics; applied science recruits theories expressed as guidelines; and engineering recruits principles. …….
The different types of knowledge and the different types of practice have important consequences for the effectiveness of any discipline of HCI. Heuristics are easy to generate, but offer no guarantee that the design solution will exhibit the properties of performance desired. Scientific theories are difficult and costly to generate, and the guidelines derived from them (like heuristics) offer no final guarantee concerning performance. Engineering principles would offer guarantees, but are predicted to be difficult…….
…….suggest that the initial creation of discipline knowledge, whether heuristics, guidelines or principles, in all cases requires a reflexive cognitive act involving intuition and reason. Thus, contrary to common assumption, the craft, applied science, and engineering conceptions of the discipline of HCI are similarly reflexive with regard to the general design problem. The initial generation of albeit different discipline knowledges requires in each case the reflexive cognitive act of reason and intuition. ……..
However, there is a case for mutual support of conceptions and it is presented here as a final conclusion. The case is based on the claim made earlier that the creation of discipline knowledge of each conception of HCI requires a reflexive cognitive act of reason and intuition. If the claim is accepted, the reflexive cognitive act of one conception might be usefully but indirectly informed by the discipline knowledge of another.
References
See full version of the paper, referenced in 3.5.