Dowell and Long (1989)
Summary Version
The EU Conception of the HCI Engineering general design problem is expressed informally as: ‘to design human interactions with computers for effective working.’ (C1) The EU 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. Engineering knowledge, in the form of principles, would be expressed in terms of those same concepts). (C2) (F1)
The EU Conception of the HCI Engineering design problem presupposes an associated HCI Discipline having three primary characteristics: a general problem; practices providing solutions to that problem; and knowledge supporting those practices. (C3) The EU conception of the design problem 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 EU 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: work, both as concerns individuals and the organisations in which it occurs.
The EU 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) (F2) 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 approaches to HCI engineering, of which EU engineering is one. (C9)
The EU Conception of the HCI Engineering design problem asserts a fundamental distinction between behavioural systems, which perform work and a world in which work originates, is performed and has its consequences. (C13) Effectiveness derives from the relationship of an interactive worksystem with its domain of application, assimilating both the work performed by the worksystem and the costs it incurs. (C14) The concern of the associated HCI Engineering discipline is to design the interactive worksystem for performance. (C15). The interactive worksystem 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 EU Conception, the general design problem of HCI Engineering is to produce implementable designs of human behaviours, which, interacting with computer behaviours, are constituted within a worksystem, whose performance conforms with some desired performance. (C17) The interactions take place in a world in which work originates and has its consequences. (C18) This work arises at the intersection of organisations and computer technology and is expressed in terms of objects. The latter may be both abstract, as well as physical and are characterised by their attributes. (C19) Abstract attributes are of information and knowledge. Physical attributes are of energy and matter. The different attributes of an object emerge at different levels within a hierarchy of levels of complexity. (C20) Attributes of objects are related in two ways – at different levels of complexity and within those levels. (C21) Attributes have states, which change or are changed over time. Thus, objects exhibit an affordance for transformation, expressed by their attributes’ potential for change of state. (C22) A domain of application is conceptualised as: ‘a class of affordance of a class of objects’. (C23)
Following the EU Conception, organisations are conceived as having domains as their operational scope and requiring the realisation of the affordance of objects. It is a requirement satisfied by work. (C24) Organisations express their requirement for the transformation of objects by formulating goals. A product goal specifies a required transformation, realised by means of the affordance of objects. (C25) The concept of Quality describes the variance of an actual transform with that specified by a product goal. An EU HCI Engineering problem exists, when actual Quality is not equal to desired Quality. (C26) Conception of the domain is of objects, characterised by their attributes and exhibiting an affordance, arising from the potential changes of state of those attributes. (C27)
The EU Conception identifies interactive worksystems, consisting of human and computer behaviours together performing work. (C28) Humans formulate goals and their corresponding behaviors 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 worksystem is a behavioural system distinguished by a boundary, enclosing all human and computer behaviours, whose purpose is to achieve a common goal. (C29) Worksystems achieve goals by the transformation of objects, that is, by producing state changes in the abstract and physical attributes of those objects. (C30) The behaviors of the human and computer are conceptualised as behavioral sub-systems of the worksystem – sub-systems, which interact. (C31) Behavior may be loosely understood as ‘what the user does’ in contrast with ‘what is done’, that is, attribute state changes of the domain. More precisely, the user is conceptualised as a system of distinct, but related, human behaviours identifiable as the sequence of states of a person interacting with a computer to perform work and corresponding with an intentional transformation of objects in a domain. Although possible at many levels, the user must be at least conceptualised at a level commensurate with the level of description of the transformation of objects in the domain. (C32)
In the EU Conception, worksystem behaviours are both physical and abstract. (C33) The latter process information, concerning object-attribute-state changes in the domain, whose transformation is required by goals. Physical behaviours are related to, and express, abstract behaviors. In addition, the user is conceptualised as having cognitive (knowing), conative (trying) and affective (experiencing) aspects. (C34) 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. Conceptualisation of the user as a system of human behaviours is extended to the structures enabling behaviours. (C37) There is a one-to-many mapping between a human’s structures and the behaviours they might enable. The structures may support many different behaviours. Physical human structures are neural, biomechanical and physiological. Mental structures consist of representations and processes, which transform them, (C38)
Work performed by interactive worksystems incurs ‘resource costs’. (C39) Certain costs are associated with the user and distinguished as structural human costs and behavioural human costs. Structural human (‘set-up’ or learning) costs are incurred in the development of human skills and knowledge, as in training and education. Such costs are both mental and physical. (C40) Behavioral human costs are incurred, when the user recruits human structures to perform work. Such costs are both mental and physical. (C41)
In the EU Conception of the HCI Engineering design problem, effectiveness derives from the relationship of an interactive worksystem with its domain. Effectiveness assimilates both the quality of the work performed by the worksystem and the costs incurred by it. (C42) Quality and costs are the primary constituents of the concept of performance through which effectiveness is expressed. A desired performance of an interactive worksystem is conceptualised such that desired performance might be either absolute or relative, as in a comparative performance to be matched or improved upon. (C43) This EU Engineering Conception of performance has the following implications.
First, the quality of the transform, expressing performance, is distinguished from the effectiveness of the worksystem, which produces it. (C44) Second, optimal human behaviours are conceived as those incurring the minimum resource costs in producing a given transform. (C45) Third, common measures of ‘human performance’ – such as ‘time and errors’- are related to performance, as conceived here. (46) Errors may increase resource costs and/or reduce quality. The time taken by human behaviours may (very generally) be associated with increased user costs. Fourth, structural and behavioural human costs may be traded off in performance. (C47) Finally, fifth, user and computer costs may also be traded off. (C48) This concludes a summary of the EU Conception of the HCI Engineering 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. In addition, it is a pre-requisite for developing formal HCI Engineering design knowledge as principles to support ‘specify then implement’ HCI engineering design practices. A complete version of the Conception can be found in the short and full versions of the Dowell and Long (1989) original paper – see 2.4 and 2.5.
Footnotes and CitationsFootnotes
(F1) Other types of design knowledge may also be expressed, using the concepts of the design problem expression, for example, models and methods.
(F2) Implement and test practices also include: trial-and error; prototype and iterate; etc.
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 – it assimilates both the quality of the work performed by the worksystem, and the costs it incurs. ‘(Page 1522, Lines 9-11)
(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) ‘Work occurs in a world consisting of objects and arises in the intersection of organisations and (computer) technology. Objects may be both abstract as well as physical, and are characterised by their attributes.’ (Page 1523, Lines 22-24)
(C20) ‘The different attributes of an object may emerge at different levels within a hierarchy of levels of complexity (see Checkland, 1981).’ (Page 1523, Lines 30 and 31)
(C21) ‘Attributes of objects are related, and in two ways. First, attributes at different levels of complexity are related. ……..’ (Page 1523, Lines 42 and 43) Second, attributes of objects are related within levels of complexity. …….. (Page 1524, Line 11) (C22) ‘At any point or event in the history of an object, each of its attributes is conceptualised as having a state. Further, those states may change. …….. Objects exhibit an affordance for transformation, engendered by their attributes’ potential for state change (see Gibson, 1977).’ (Page 1524, Lines 15-17 and 19-20)
(C23) ‘A domain of application may be conceptualised as: ‘a class of affordance of a class of objects’.’ (Page 1524, Lines 30 and 31)
(C24) ‘Organisations are conceptualised as having domains as their operational province and of requiring the realisation of the affordance of objects. It is a requirement satisfied through work.’ (Page 1524, Lines 36-38)
(C25) ‘Organisations express their requirement for the transformation of objects through specifying goals. A product goal specifies a required transform – a required realisation of the affordance of an object.’ (Page 1524, Lines 45 and 46; Page 1525, Line 1)
(C26) ‘The transformation of an object demanded by a product goal will generally be of a multiplicity of attribute state changes – both within and across levels of complexity. ……… The concept of quality (Q) describes the variance of an actual transform with that specified by a product goal. It enables all possible outcomes of work to be equated and evaluated.’ (Page 1525, Lines 23-25 and 29-31)
(C27) ‘Conception of the domain then, is of objects, characterised by their attributes, and exhibiting an affordance arising from the potential changes of state of those attributes.’ (Page 1525, Lines 32-34)
(C28) ‘The conception for HF identifies interactive worksystems consisting of human and computer behaviours together performing work.’ (Page 1526, Lines 2 and 3)
(C29) ‘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)
(C30) ‘Worksystems transform objects by producing state changes in the abstract and physical attributes of those objects (see Section 2.2).’ (Page 1526, Lines 17 and 18)
(C31) ‘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)
(C32) ‘Although possible at many levels, the user must at least be expressed at a level commensurate with the level of description of the transformation of objects in the domain.’ (Page 1526, Lines 33-35)
(C33) ‘The behaviours constituting a worksystem are both physical as well as abstract.’ (Page 1526, Lines 39 and 40)
(C34) ‘The user is conceptualised as having cognitive, conative and affective aspects.’ (Page 1527, Line 19)
(C35) ‘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)
(C36) ‘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)
(C37) ‘Conceptualisation of the user as a system of human behaviours needs to be extended to the structures supporting behaviors.’ (Page 1528, Lines 26 and 27)
(C38) ‘Physical human structure is neural, biomechanical and physiological. Mental structure consists of representational schemes and processes.’ (Page 1528, Lines 40 and 41)
(C39) ‘Work performed by interactive worksystems always incurs resource costs.’ (Page 1529, Lines 37 and 38)
(C40) ‘Structural human costs are the costs of the human structures co-extensive with the user.’ (Page 1529, Lines 41 and 42)
(C41) ‘Behavioral human costs are the resource costs incurred by the user (i.e. by human behaviours) in recruiting human structures to perform work. They are both physical and mental resource costs.’ (Page 1530, Lines 12-14)
(C42) ‘The costs of work are conceptualised as the resource costs incurred by the worksystem, and are separately attributed to the human and computer.’ (Page 1531, Lines 1 and 2)
(C43) ‘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.’ (Page 1531, Lines 8-10)
(C44)…….. the conception of performance is able to distinguish the quality of the transform from the effectiveness of the worksystems which produce them.’ (Page 1531, Lines 17 and 18)
(C45)…….. given the concordance of behaviour with performance, optimal human (and equally, computer) behaviours may be conceived as those which incur a minimum of resource costs in producing a given transform.’ (Page 1531, Lines 22-24)
(C46)……..’the common measures of human ‘performance’ – errors and time, are related in this conceptualisation of performance.’ (Page 1531, Lines 34 and 35)
(C47) …….. ‘structural and behavioural human costs may be traded-off in performance.’ (Page 1531, Line 39)
(C48)……..’resource costs incurred by the human and the computer may be traded-off in performance.’ (Page 1531, Lines 43 and 44)
(C49)……..’ 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)