The Conception of the HCI Engineering (F1) general design problem is expressed informally as: ‘to design human interactions with computers to perform tasks effectively.’ (C1) The Engineering Conception is a unitary view of a general design problem; its power lies in the coherence and completeness of its definition of the concepts, which can express that problem (note: engineering knowledge would be expressed in terms of these concepts). (C2) (F2)
The Engineering Conception of the HCI design problem presupposes an associated HCI Engineering Discipline having three primary characteristics: a general problem; practices providing solutions to that problem; and knowledge supporting those practices. (C3) The Engineering Conception belongs to the class of general design problem and includes the design of artefacts (for example, bridges) and the design of states of the world (for example, public administration). (C4) The Engineering Conception has the necessary property of a scope, delimiting the province of concern of the associated discipline of HCI Engineering. (C5) The scope includes: humans, both as individuals, groups and as social organisations. It also includes computers, both as programmable machines, stand-alone and networked, and as functionally embedded devices within machines. Its scope also includes: tasks, both as concerns individuals and the organisations in which it occurs. (C6) (F3)
The Engineering Conception categorises HCI Engineering design problems as ‘hard’ or ‘soft’. Hard and soft problems are distinguished by the need for engineering design solutions, as specified by HCI design practices, to be determinate. The design practices vary in the completeness of their specification before implementation. ‘Specify then implement’ design practices (based on formal design knowledge, such as principles) implicate more complete specification. ‘Implement and test’ design practices (based on informal design knowledge, such as guide-lines) implicate less complete specification. (C8) Taken together, the dimension of problem hardness, characterising HCI general design problems and the dimension of specification completeness, characterising HCI practices, constitute a classification space for Engineering approaches to HCI. (C9)
The Engineering Conception of the HCI design problem asserts a fundamental distinction between behavioural systems, which perform tasks and a world in which tasks originate, are performed and have their consequences. (C13) Effectiveness derives from the relationship of an interactive system with its domain of application, assimilating both how well the tasks are performed by the system and the resources they consume. (C14) (F4) The concern of the associated HCI Engineering discipline is to design the interactive system for performance. (C15). The interactive system is constituted of two separate, but interacting sub-systems, that is, a system of human behaviours, interacting with a system of computer behaviours. (C16)
According to the Engineering Conception, the general design problem of HCI is to produce implementable designs of human behaviours, which, interacting with computer behaviours, are constituted within a system, whose performance conforms with some desired performance. (C17) The interactions take place in a world in which tasks originate and have their consequences. (C18) These tasks arise at the intersection of organisations and computer technology and require representation for the purposes of design. The tasks may be both abstract and physical. The abstract representation of tasks includes information and knowledge. The physical representation includes energy and matter. Different representations of tasks emerge at different levels of description. Representations may be related in two ways – at different levels of description and within those levels. Tasks involve changes over time. Thus, representations of tasks exhibit an affordance for transformation, expressed by the ‘potential’ for change effected by tasks. A domain of application is conceptualised as: ‘a class of affordance of a class of representations of tasks’.
Following the Engineering Conception, organisations are conceived as having domains as their operational scope and requiring the realisation of the affordance of representations of tasks. It is a requirement satisfied by the performance of tasks. (C19) Organisations express their requirement for the performance of tasks by formulating goals. A product goal specifies a required change, realised by means of the performance of tasks. A variance exists, if the required change differs from that specified by a product goal. An HCI Engineering design problem exists, when actual task performance is not equal to desired performance. (F5) The Engineering Conception identifies interactive systems, consisting of human and computer behaviours together performing tasks. (C20) Humans formulate goals and their corresponding behaviours are said to be intentional (or purposeful). Computers are designed to achieve goals and their corresponding behaviours are said to be intended (or purposive). An interactive system is a behavioural system distinguished by a boundary, enclosing all human and computer behaviours, whose purpose is to achieve a common goal. (C29) Interactive systems achieve goals by the performance of tasks, that is, by producing change. (C21)
The behaviors of the human and computer are conceptualised as behavioral sub-systems of the worksystem – sub-systems, which interact. (C22) Behavior may be loosely understood as ‘what the user does’ in contrast with ‘what is done’, that is, changes effected by tasks in the domain. More precisely, the user is conceptualised as a system of distinct, but related, human behaviours identifiable as the sequence of actions of a person interacting with a computer to perform tasks and corresponding with an intentional change in the domain. Although possible at many levels, the user must be at least conceptualised at a level commensurate with the level of description of the changes effected by tasks in the domain.
In the Engineering Conception, interactive system behaviours are both physical and abstract. (C23) The latter process information, concerning task changes in the domain, required by goals. Physical behaviours are related to abstract behaviors. The user may include both on-line and off-line human behaviours. On-line behaviours are associated with the computer’s representation of the domain; 0ff-line behaviours are associated with non-computer representations of the domain or the latter itself. (C25)
Tasks performed by interactive systems consume its resources. Certain resources are associated both with the user and others with the computer. Such resources may be both mental and physical. (F6) In the Engineering Conception of the HCI design problem, effectiveness derives from the relationship of an interactive system with its domain. Effectiveness assimilates both how well the tasks are performed by the system and the resources consumed by it in so doing. These are the primary constituents of the concept of performance through which effectiveness is expressed. A desired performance of an interactive system is conceptualised such that desired performance might be either absolute or relative, as in a comparative performance to be matched or improved upon. (C27)
This concludes the expression of the Engineering Conception of the HCI design problem. The Conception is a unitary view of the necessary concepts and their relations to express that design problem and so, any design solution.
Key concepts are shown in bold on their first appearance only.
Footnotes and CitationsFootnotes
(F1) Engineering here is contrasted, for example, with Science.
(F2) Engineering approaches may themselves vary, for example, depending on the type of knowledge they acquire and apply. However, the present conception is intended to be general to all engineering approaches.
(F3) The use of ‘task’ here is in no way restrictive. Tasks may be more-or-less well specified, according to the engineering approach in question.
(F4) ‘Resources’ may be variously conceptualized, for example, as: effort; affect; knowledge etc.
(F5) There are many different expressions of performance, for example: effectiveness; efficiency; time and errors; safety; expedition etc.
(F6) See F4 above.
Citations
Dowell and Long (1989)
(C1) ‘…….. a conception of the general design problem …….. is expressed informally as: ‘to design human interactions with computers for effective working’.’ (Page 1513, Lines 12-13)
(C2) ‘A conception is a unitary (and consensus) view of a general design problem; its power lies in the coherence and completeness of its definition of the concepts which can express that problem. Engineering principles are articulated in terms of those concepts. Hence, the requirement for a conception for the HF discipline is concluded (Section 1.5.).’ (Page 1514, Lines 19-22)
(C3) ‘Most definitions of disciplines assume three primary characteristics: a general problem; practices, providing solutions to that problem; and knowledge, supporting those practices.’ (Page 1514, Lines 39-41)
(C4) ‘…….. one class of general problem is that of the general design problem and includes the design of artefacts (of bridges, for example) and the design of ‘states of the world’ (of public administration, for example).’ (Page 1524, Lines 43-45)
(C5)’…….. any general problem has the necessary property of a scope, delimiting the province of concern of the associated discipline.’ (Page 1514, Lines 47 and 48)
(C6) The scope of the HCI general design problem includes: humans, both as individuals, as groups, and as social organisations; computers, both as programmable machines, stand-alone and networked, and as functionally embedded devices within machines; and work, both with regard to individuals and the organisations in which it occurs. (Page 1515, Lines 11-14)
(C7) ‘…….. The ‘design’ disciplines are ranged according to the ‘hardness’ or ‘softness’ of their respective general design problems. …….. However, here hard and soft problems will be generally distinguished by their determinism for the purpose, that is, by the need for design solutions to be determinate.’ (Page 1517, Lines 31 and 32 and 38-40).
(C8) ‘A discipline’s practices construct solutions to its general design problem…….. disciplines appear to differ in the completeness with which they specify solutions to their respective general design problems before implementation occurs. ……..’ (Page 1517, Line 46; Page 1518, Lines 2 and 3).
(C9) ‘Taken together, the dimension of problem hardness, characterising general design problems, and the dimension of specification completeness, characterising discipline practices, constitute a classification space for design disciplines……..’ (Page 1518, Lines 20-22)
(C10) ‘First, a general relation may be apparent between the hardness of a general design problem and the realiseable completeness with which its solutions might be specified. (Page 1518, Lines 20-22)
(C11) ‘Whilst the realiseable completeness with which a discipline may specify design solutions is governed by the hardness of the general design problem, the actual completeness with which it does so is governed by the formality of the knowledge it possesses.’ (Page 1519, Lines 15-18)
(C12)’…….. there exists no pre-ordained relationship between the formality of a discipline’s knowledge and the hardness of its general design problem.’ (Page 1519, Lines 31-33)
(C13) ‘The conception for the (super-ordinate) engineering discipline of HCI asserts a fundamental distinction between behavioural systems which perform work, and a world in which work originates, is performed and has its consequences.’ (Page 1522, Lines 2-4)
(C14) ‘Effectiveness derives from the relationship of an interactive worksystem with its domain of application. ‘(Page 1522, Lines 9 and 10)
(C15) ‘The concern of an engineering HCI discipline would be the design of interactive worksystems for performance.’ (Page 1522, Lines 13 and 14)
(C16) ‘The interactive worksystem can be distinguished as two separate, but interacting sub-systems, that is, a system of human behaviours interacting with a system of computer behaviours.’ (Page 1523, Lines 1-3)
(C17) ‘The general design problem of HF then, is one of producing implementable specifications of human behaviours {U} which, interacting with computer behaviours {C}, are constituted within a worksystem {S} whose performance conforms with a desired performance (Pd).’ (Page 1523, Lines 11-14)
(C18) ‘The conception for HF identifies a world in which work originates, is performed and has its consequences. This section presents the concepts by which work and its relations with the user are expressed.’ (Page 1523, Lines 19 and 20)
(C19) ‘Organisations are conceptualised as having domains as their operational province …….. It is a requirement satisfied through work.’ (Page 1524, Lines 36-38)
(C20) ‘The conception for HF identifies interactive worksystems consisting of human and computer behaviours together performing work.’ (Page 1526, Lines 2 and 3)
(C21) ‘Humans are able to conceptualise goals and their corresponding behaviours are said to be intentional (or purposeful). Computers, and machines more generally, are designed to achieve goals, and their corresponding behaviours are said to be intended (or purposive1). An interactive worksystem (‘worksystem’) is a behavioural system distinguished by a boundary enclosing all human and computer behaviours whose purpose is to achieve and satisfy a common goal.’ (Page 1526, Lines 5-11)
(C22) ‘The behaviours of the human and computer are conceptualised as behavioural sub-systems of the worksystem – sub-systems which interact.’ (Page 1526, Lines 24 and 25)
(C23) ‘The behaviours constituting a worksystem are both physical as well as abstract.’ (Page 1526, Lines 39 and 40)
(C24) ‘Although the human and computer behaviours may be treated as separable sub-systems of the worksystem, those sub-systems extend a “mutual influence”, or interaction whose configuration principally determines the worksystem (Ashby, 1956).’ (Page 1527, Lines 24-27)
(C25) ‘The user may include both on-line and off-line human behaviours: on-line behaviours are associated with the computer’s representation of the domain; offline behaviours are associated with non-computer representations of the domain, or the domain itself.’ (Page 1528, Lines 8-11)
(C26) ‘Physical human structure is neural, bio-mechanical and physiological. Mental structure consists of representational schemes and processes.’ (Page 1528, Lines 40 and 41)
(C27) ‘A desired performance of an interactive worksystem may be conceptualised. Such a desired performance might either be absolute, or relative as in a comparative performance to be matched or improved upon.’ (Pages 1531. Lines 8-10)
(C28)……..’ Instances of the general design problem may include the development of a worksystem, or the utilisation of a worksystem within an organisation. Developing worksystems which are effective, and maintaining the effectiveness of worksystems within a changing organisational environment, are both expressed within the problem.’(Page 1532, Lines 16-20)