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.
Pre-print: In: Sutcliffe, A. andMacaulay, L., (eds.) People and Computers V: Proceedings of the Fifth Conference of the British Computer Society.(pp. pp. 9-32). Cambridge University Press: Cambridge, UK. http://discovery.ucl.ac.uk/15292/ .
….. 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’. Second, the scope of the general problem of HCI is defined by reference to humans, computers, and the work they perform. Third, by intersecting these two definitions, a framework is proposed ……
The framework expresses the essential characteristics of the HCI discipline, and can be summarised as: ‘the use of HCI knowledge to support practices seeking solutions to the general problem of HCI’……
Contents 1. Introduction 1.1. Alternative Interpretations of the Theme 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 2.2. Of Humans Interacting with Computers 2.3. The Framework for Conceptions of the HCI Discipline 3. Three Conceptions of the Discipline of HCI 3.1. Conception of HCI as a Craft Discipline 3.2. Conception of HCI as an Applied Science Discipline 3.3. Conception of HCI as an Engineering Discipline 4. Summary and Conclusions
1. Introduction
1.1. Alternative Interpretations of the Theme……..
1.2. Alternative Conceptions of HCI: the Requirement for a Framework …….. A conception of the HCI discipline offers a unitary view; its value lies in the coherence and completeness with which it enables understanding of the discipline, how the discipline operates, and its effectiveness…….. A suitable structure for this purpose would be a framework identifying the essential characteristics of the HCI discipline……..
1.3. Aims ….. the aims of this paper are as follows: (i) to propose a framework for conceptions of the HCI discipline
2. A Framework for Conceptions of the HCI Discipline
Two prerequisites of a framework for conceptions of the HCI discipline are assumed. The first is a definition of disciplines appropriate for the expression of HCI. The second is a definition of the province of concern of the HCI discipline, which, whilst broad enough to include all disparate aspects, enables the discipline’s boundaries to be identified. Each of these prerequisites will be addressed in turn (Sections 2.1. and 2.2.). From them is derived a framework for conceptions of the HCI discipline (Section 2.3.). Source material for the framework is to be found in (Dowell & Long [1988]; Dowell & Long [manuscript submitted for publication]; and Long [1989]).
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…….. 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. Consideration of different disciplines suggests that practice is also a necessary characteristic of a discipline. Further, a discipline’s knowledge is used by its practices to solve a general (discipline) problem. …….. The discipline of engineering includes the engineering practice addressing the general (engineering) problem of design. …….. Practice, therefore, and the general (discipline) problem which it uses knowledge to solve, are also necessary characteristics of a discipline. Clearly, disciplines are here being distinguished by the general (discipline) problem they address. …….. Yet consideration also suggests those general (discipline) problems each have the necessary property of a scope. Decomposition of a general (discipline) problem with regard to its scope exposes (subsumed) general problems of particular scopes……. 
Two basic properties of disciplines are therefore concluded. One is the property of the scope of a general discipline problem. The other is the possibility of division of a discipline into sub-disciplines by decomposition of its general discipline problem. Taken together, the three necessary characteristics of a discipline (and the two basic properties additionally concluded), suggest the definition of a discipline as: ‘the use of knowledge to support practices seeking solutions to a general problem having a particular scope’. It is represented schematically in Figure 1. This definition will be used subsequently to express HCI.
2.2. Of Humans Interacting with Computers
The second prerequisite of a framework for conceptions of the HCI discipline is a definition of the scope of the general problem addressed by the discipline. In delimiting the province of concern of the HCI discipline, such a definition might assure the completeness of any one conception (see Section 1.2.). HCI concerns humans and computers interacting to perform work. ……. Further, since both organisations and individuals have requirements for the effectiveness with which work is performed, also implicated is the optimisation of all aspects of the interactions supporting effectiveness. Taken together, these implications suggest a definition of the scope of the general (discipline) problem of HCI. It is expressed, in summary, as ‘humans and computers interacting to perform work effectively’; it is represented schematically in Figure 2. This definition, in conjunction with the general definition of disciplines, will now enable expression of a framework for conceptions of the HCI discipline. 
2.3. The Framework for Conceptions of the HCI Discipline ….. Given the definition of its scope (above), and the preceding definition of disciplines, the general problem addressed by the discipline of HCI is asserted as: ‘the design of humans and computers interacting to perform work effectively’. It is a general (discipline) problem of design : its ultimate product is designs. The practices of the HCI discipline seek solutions to this general problem, for example: in the construction of computer hardware and software; in the selection and training of humans to use computers; in aspects of the management of work, etc. HCI discipline knowledge supports the practices that provide such solutions. ….. 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…… Importantly, the framework supposes the nature of effectiveness of the HCI discipline itself. There are two apparent components of this effectiveness. The first is the success with which its practices solve the general problem of designing humans and computers interacting to perform work effectively. It may be understood to be synonymous with ‘product quality’. The second component of effectiveness of the discipline is the resource costs incurred in solving the general problem to a given degree of success – costs incurred by both the acquisition and application of knowledge. It may be understood to be synonymous with ‘production costs’. Figure 3. Framework for Conceptions of the Discipline of HCI ……
3. Three Conceptions of the Discipline of HCI A review of the literature was undertaken to identify alternative conceptions of HCI, that is, conceptions of the use of knowledge to support practices solving the general problem of the design of humans and computers interacting to perform work effectively. The review identified three such conceptions. They are HCI as a craft discipline; as an applied scientific discipline; and as an engineering discipline……..
3.1. Conception of HCI as a Craft Discipline …….. Figure 4 Conception of HCI as a Craft Discipline ……..
3.2. Conception of HCI as an Applied Science Discipline …….. Figure 5 Conception of HCI as an Applied Science Discipline ……..
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. And further, engineering disciplines may solve their general problem by exploiting a decompositional approach to design. Designs specified at a general level of description may be systematically decomposed until their specification is possible at a level of description of their complete implementation. Engineering principles may assure each level of specification as a representation of the previous level. This Section summarises the conception (schematically represented in Figure 6) and attempts to indicate the effectiveness of such a discipline. 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. …….. 
……..The concepts described enable the expression of the general problem addressed by an engineering discipline of HCI as: specify then implement user behaviour {U} and computer behaviour {C}, such that {U} interacting with {C} 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 behaviour of the user.
4. Summary and Conclusions
…….. The proposal made here is that the general problem of HCI is the design of humans and computers interacting to perform work effectively. The qualification of the general problem as ‘design’, and the addition to the scope of that problem of ‘…. to perform work effectively’, has important consequences for the different conceptions of HCI….. ….. The different types of knowledge and the different types of practice have important consequences for the effectiveness of any discipline of HCI……
References
For References – see the full version of the paper 1.5.