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2: The History and Component Fields of Human-Centered Design [Churchill]

This book should help its readers to reflect about design from a human-centered perspective and to begin to understand what questions to ask in a design situation (about physical, physiological, cognitive, and social processes). This book notes the importance of asking questions, engaging in critical reflection and carrying out iterative evaluation. This chapter introduces some of the major terms and lays out a high level organization, that of the fields that study users and their tasks.

2.1 Introduction

In this chapter we offer a brief introduction to the history of user centered design. The two disciplines that are most directly concerned with user-centered design are Human Factors (HF) and Ergonomics. More specifically focused on designing for people’s interaction with computer-based applications and systems are the areas of Human Computer Interaction (HCI) and Information Science, and concerned with people’s communication through computer-based applications is the field of Computer Supported Cooperative Work (CSCW). A priority is consideration of users' physical, behavioral and information processing characteristics and requirements. Experience has shown that failure to deal with such characteristics can lead to wasted functionality, user frustration, inefficient practices, discomfort, and error-prone activity. However, much of human factors work is a trade-off between considering the user and economic and political constraints.

These fields do not represent coherent bodies of knowledge but pragmatic amalgams of potentially useful approaches to and data about practical problems. This means there is no single definition, or description of human factors practice; there are a number of areas of knowledge that focus on people in the work place. These areas cannot be subsumed under one title because they reflect many different approaches that are often theoretically inconsistent and even contradictory. Related activities include scientific management; industrial, occupational and social psychology; human relations; organizational behavior; work psychology; and of course human factors. Given this broad view of Human Factors, it is not surprising that HF involves multidisciplinary research, including input from engineering, cognitive psychology, organizational/occupational psychology, anthropology, sociology, social psychology, linguistics, and mathematics. It is also concerned with legal, psychological, organizational, and occupational considerations.

Before detailing general ideas within human factors and ergonomics we give a short overview of the history of these fields. This will also help you understand the relationships of the various fields that study users.

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2.2 A historical perspective of studying the user

The history of Human Factors/Ergonomics work is linked to the political and economic climate in which workers find themselves. Three strands can be seen in the work that has been carried out: characterizing and changing the user through training; characterizing and designing the social and physical environment including the specific tools that are used; characterizing and defining the task. These three components are all part of designing the fit between the person, the environment and tools, and the task. Work on choosing users to fit the task are part of IO psychology, and human resource selection, and are not covered in this book.

Within both Britain and the US, Human Factors as a discipline has its roots in WWI work on fatigue, in early work on time-motion analysis, and in early work on organizational psychology. There was also a concentration on anthropometric issues pre-WW1, looking at can something be used, for example, looking at issues such as the effects of desk height of work. This work brought together engineering, physiological, and psychological approaches.

But the roots of Human Factors go further back and also draw on early work in psychology. Brown (1977) traces the roots of Human Factors to the late 19th century and the emergence of the (non-applied) discipline of experimental psychology. For example, Galton in the 1880's looked at interpersonal differences in intellect and mental imagery and Catell in 1890's looked at differences in sensory motor capabilities, reaction times and problem solving abilities that provided a foundation for IQ tests and personality trait work. These were the beginnings of psychometric testing, a practice still popular within vocational and personnel work.

As educationalists, Ebbinghaus and Binet were the first people to look at individual differences and intellectual ability. To a large extent, the study of individual differences has been marginalized within mainstream cognitive psychology, the notion that traits are singular and measurable being saved for magazine questionnaires. However, developments in complex factor analysis and improvements in contextualized analyses of performance have offered ways of looking at the interaction of certain individual characteristics within particular contexts. These more recent trends, however, stress the possibility for change and do not attempt to make the long-term predictions that the original work in IQ measures did make.

Whilst experimental psychology was developing in the UK, within the USA two distinct engineering approaches to the study of human behavior were developing. The first, the Gilbreths (late 19th and early 20th century) pioneered the concept of the motion study as a technique for improving worker efficiency. They believed that any task could be broken down into individual motions or manipulations, and that it was the nature of these motions that determined overall efficiency. Remember this when we discuss task analysis. There are two interesting books on this. One, by Gillian Gilbreth, The one best way (1990), helped establish her as one of the first engineering psychologists, as one of the first female psychologists, and as an entertaining writer. The other, by their oldest son, Frank, Cheaper by the dozen, illustrates how their work influenced their family life. This has also been made into one of the few movies to have Human Factors experts as the protagonists (the first movie with this title spoke to this, the recent movie just uses the title). They also introduced the concept of fundamental steps in work, called

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therbligs (basically, Gilbreth spelled backwards). These can be seen as a precursor to GOMS and other forms of task analyses we take up in a later chapter.

The second, Frederick Taylor was a contemporary of the Gilbreths. He had an alternative approach called the t ime study. Taylor believed that skilled behavior should be defined more in terms of the sequencing of motions made by an operator and the speed at which they were carried out rather than in terms of the individual units of movement themselves. Taylor's technique consisted of rationalizing a particular task into its most economical sequence of actions and determining the maximum rate for these actions that would not overtire the operatives performing them. Taylor’s methods were applied by Henry Ford.

Taken together, time and motion studies proved to be a powerful management tool for determining realistic work schedules, setting basic pay scales and generally improving the efficiency of the production process. Although this was associated with reducing staff and became a highly politicized movement because of the emphasis on the output and not the worker.

The outbreak of WWI provided a stimulus for these and other early human factors studies. The need to expand the armed services to many times their pre-war size meant that large numbers of civilians had to be conscripted and sorted according to their abilities. Large scale testing was undertaken to sort people into potential pilots, telegraphers, etc. Also women took the place in the factories of the men who were away. They had to learn skilled trades rapidly and were faced with workloads that far exceeded normal capacity due to the need for war materials to keep the armed forces supplied. This was a highly motivated work force. Many people offered to work overtime, sometimes working up to 100 hours per week. The unexpected results of this were the decline in production due to ill health and low moral, despite the initial motivation. To combat this in the UK, the Department of Scientific and Industrial Research and the Medical Research Council were asked to investigate the conditions of industrial workers in 1917 and shortly afterwards the Committee on the Health of Munitions Workers (later the Industrial Fatigue Research Board) was appointed to investigate the causes of fatigue among munitions workers. Under the direction of this Committee research workers from the biological sciences were called in for the first time to investigate the work behavior in real industrial settings. At this time similar work went on in the US as well.

There were cultural differences in the response to this work between the USA and Britain. Before the Second World War "industrial" psychology was the most common term for studies of work environments, people and performance—this had a very different emphasis in the US than in Britain. In the US it came almost exclusively to mean psychometric testing, whereas in Britain it included fatigue research, working conditions and job design, all of which were referred to as "human factors". In addition, in Britain the force of the Trade Unions meant that management efficiency issues were balanced with consideration of work environments from the worker's perspective. However, the political problems caused by the use of time and motion studies and debates about the dehumanization of the worker left a tendency to mistrust ergronomists and human factors workers. In more recent years, with the development and promotion of user-centered design issues this bad reputation has finally been reduced.

The inter-war years were a slow period for Human Factors. However there were two important developments during this time: the foundation of the Cambridge Psychological

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Laboratory in 1921 in the UK and the Hawthorne studies carried out during the late 1920's and the early 1930's in the US. The Cambridge Laboratory was a non-profit making organization designed to continue the collaboration of researchers and practitioners begun during the war by making the results of physiological and psychological research available to industry.

Elton Mayo’s Hawthorne Experiments, which took place between 1927 and 1932 at the Western Electric Hawthorne Works near Chicago looked at the effects of changing the working environment and monotony on fatigue and motivation. He looked at alterations in working conditions (specifically changes in lighting levels) on performance efficiency. It appeared that changes in such levels could significantly affect people’s performance. On closer appearance however, he discovered that initial improvements he observed were, in fact, caused by the fact that the work was being observed, and that the effects was not a consequence of actual changes in working conditions but because management demonstrated interest in such improvements. Mayo’s observations revolutionized the field of management; the studies showed that the most important factor in determining performance efficiency and productivity was psychological rather than physiological in nature.

The Hawthorne effect now applies to any situation where being new or novel causes the success rather than changes in underlying fundamentals. If a computer manufacturer released a new type of laptop that was different in some surface way, it may be initially successful because of the attention paid to its newness. If a new teaching innovation is put into a classroom, for example, a reversion to chalkboards at this point, one might see an initial improvement in learning because of the shared additional attention and expectations about learning arising from the innovation, not from the use per se of the innovation.

In the 30's with the economic recession, Human Factors work fel l into a hiatus. There were so many applicants for each job that improving working conditions was not a necessity for most organizations.

However, WWII broke out and again workers needed to be allocated and trained quickly and so work in HF and selection once again took off. In UK there was an acute shortage of aircraft. So in 1942, the Production Efficiency Board of the Air Ministry was set up to advise on the best means of utilizing staff. They introduced time and motion studies and personnel training schemes, and in the field of environmental psychology and physiology the Industrial Health Research Board (formed in 1929 from the old Industrial Fatigue Research Board) was called in to advise on working hours, rest pauses and environmental conditions in the factories. Workers were however under much more pressure than they had been in WWI; servicemen had to function equally efficiently in desert conditions, tropical jungles or Arctic convoys, and had to use equipment that had increased considerably in complexity, such as radar, sonar, high altitude aircraft, sophisticated weaponry, and submarines that imposed much greater demands on operator abilities.

Several bodies were set up to advise on the medical, physiological and psychological requirements of design; for example the Medical Research Council's Applied Psychology Unit (MRC/APU), the Climatic and Working Efficiency Research Unit (Oxford) and the Division of Human Physiology at Hampstead. Human factors knowledge was still fragmentary at this stage and limited in practical applications. Existing studies of fatigue were entirely about muscular fatigue rather than mental workload and skilled behavior

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was reduced to conditioning and simple reaction times. Most of the work was lab-based and not highly generalisable. The first simulator was built at the APU to observe pilots working for long hours, and found that to a large extent performance depended on the arrangement and interpretation of displays as well as controls, so had to move away from a pure muscular fatigue interpretation to cognitive one. This interest in the perceptual elements of skilled behavior represented an important departure from conventional work study methods that had previously dominated the consideration of motor abilities. It marked the beginning of a change of attitudes towards the design of machine for human use. It was henceforth realized that it may be necessary to modify the characteristics of the machine to suit the capabilities and limitations of the operator in addition to selecting and training the operator to fit the machine.

This change in design orientation represents the birth of human factors as a distinct disciple in its own right. The actual birth date of the Ergonomics Society is 12 July 1949, when a meeting was held at the British Admiralty at which an interdisciplinary group was formed (called the "Human Research Group") (Murrell, 1980). Later, at a meeting on 16th February 1950, the term ergonomics was coined. From the Greek ergon = work and nomos = natural laws. The society includes anatomists, engineers, physiologists, psychologists, industrial medical officers, and others.

2.3 More recently: Human-computer interaction and cognitive ergonomics

Moving forward in time we see the development of computer based technologies in the workplace and the introduction of user-centered design methods in areas such as Office Information Systems. As people’s work with complex interactive “thinking” machines has increased, the need for a better understanding of people’s problem solving processes has become ever more apparent, and the field of “cognitive ergonomics” more important. Indeed, since the mid-1960s and the development of integrated circuits and "third generation" computer systems, work has been carried out in user centered aspects of “data processing”, “management information systems”, “information systems”, and “information technology”.

Cognitive ergonomics is concerned with applicable, approximate models of how people perceive, process, attend to and use information to achieve what they want to or need to do. It is more important that these models are of use to designers, instructors, and users, and less important that these models are accurate or validated. Cognitive ergonomics therefore draws on many areas of psychology that are often taught separately, such as planning, language, problem-solving, learning, memory, perception, but tries to think about how such process work together. In this respect it is different to the direct application of cognitive psychology, in that it does not look at cognitive processes in isolation, but their integration and how they are involved in particular activities or situations. Cognitive ergonomics also differs from cognitive psychology in focusing on theories which can predict behavior in what have been called “real world” settings, not laboratory setting, although results from laboratory settings are considered informative. “Real world” settings may require a more detailed treatment of, for example, individual differences, uncertainty and ad hoc problem solving and so on, than many other branches of psychology. Cognitive ergonomics also has a greater emphasis on the co-agency of action between the user and the machine, but again, this is a different in emphasis and these fields overlap to a great extent.

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HCI is related to cognitive ergonomics, but focuses almost exclusively on direct human-computer interfaces. It has not in the past attempted to cover work and work places in general (e.g., chairs, tables, stairs, forklift trucks, power plants).

Human–computer interaction (HCI) is the study of interaction between people (users) and computers. The ACM in a document attempting to define an HCI curriculum (Hewett et al., 1996) defined HCI as:

"Human-computer interaction is a discipline concerned with the design, evaluation and implementation of interactive computing systems for human use and with the study of major phenomena surrounding them."

Computer-human interaction (CHI) is a related field, but with an emphasis on the computer and new types of interfaces. The Association for Computing Machinery has a subgroup, a special interest group (SIG) on Computer-Human Interaction (thus, also called SIGCHI). It was fundamental in creating, nurturing, and defining HCI as a field. But, as you examine that curriculum you will see that CHI has a greater focus on hardware and software implementation than on people themselves. But, however you define it, CHI and HCI are closely related.

Nickerson (1969, p. 178 in the IEEE version) concluded early on in the development of computers "the need for the future is not so much computer oriented people as for people oriented computers". This remains true for any artifact. We hope the remaining chapters help you to fit the machine to the user to provide better, safer, faster systems.

We will consider how to fit the machine to users more when dealing with basic issues from psychology and their impact on design. For further details on how to fit machines to users, also see work by Don Norman, Thomas Green, and the chapter on cognitive dimensions later in the book.

2.4 Designing for users as a frame of mind (the approaches)

The role and involvement of the human factors expert varies in design. The involvement depends on the ethos of the design setting (the relative importance of usability issues and the degree of focus on supporting the user). Clearly the complexity of the object being designed is also a factor. In this section we break out some of the terms that have been used.

2.4.1 Human Factors and ergonomics

The purpose of human factors (HF) research and practice is to maximize the safety and "healthiness" of work environments and work practices, and to ensure the usability of tools, devices and artifacts in general. More specifically, human factors is concerned with providing a good 'fit' between people and their work or leisure environments. 'Fit' might be the literal word as with the design of ejector seats for RAF aircraft (e.g., ejector seats designed for average size) or might be more metaphorical in the sense (e.g., designing to complement task activities).

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Traditionally providing the 'fit' between the environment and the person by altering the environment has been called 'ergonomics'. In the UK in recent years, however, Human Factors has embraced the broader context of work practices, including considering personnel and not just the redesign of the work environment. So, the USA Human Factors is called Ergonomics in the UK, however, in the UK ‘human factors’ includes ergonomics, selection, and training.

'Fitting the person to the environment' is the responsibility of selection and training, whilst ergonomists 'fit the environment to the person'. There is therefore, a complementary relationship between ergonomics and selection/training. Although they share a common goal—often only one is needed for a solution. Market forces, financial constraints, management policy, and so on all influence which of these a company emphasizes. Furthermore, whereas selection and training relate explicitly to the human resource problems at work, ergonomics is important not only for designing the work environment, it applies to any environment and any made object. Ergonomics is also important when you are a company that manufactures products for other work environments (e.g., computer manufacturers).

In the 1950's Prof. Alec Rodger encapsulated the definition of the field of occupational psychology in the slogan

"Fitting the man to the job and the job to the man” (FMJ/FJM). This was realized as:

fitting the man to the job through

occupational guidance,

personnel selection,

training and development

and

“fitting the job to the man” through

methods design,

equipment design, and

negotiation of working conditions and (physical and social) rewards (Holloway, 1991).

Rodger's definition has been critiqued as it does not take into account the organization in which the 'man' works. (And it is worth noting at this point that Rodger's language at the time used a definition of man that was intended to include both genders, or at least at this point it must.)

Notably, the 'fit' can be made in either direction. Figure 2-1 shows an approach of teaching the user to fit to the system, rather than having the system fit to the user. We can 'fit' the environment to the person (e.g., by providing adjustable ejector seats to accommodate a range of heights, weights, etc.) or we can fit the person to the environment. (e.g., extensive training or using people of a certain build, e.g., Suckling

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airlines in Cambridge). The two together (fitting users to the task and the task to the user) traditionally make up industrial psychology and used to define occupational psychology (although now the remit of occupational psychology is very large indeed). Although in this book we are not concerned with selection and training, it is worth noting that there is a complementary relationship between these activities, and that often user groups are selected to fulfill certain requirements that are specified by the working environment. Thus, training and selection can modify your user population, and are used to improve the performance of some interfaces, although this is an expensive way to do so.

Figure 2-1. An example interface that attempts to “fit the user to the machine”. (Screenshot taken by Ritter in 2009 from a university web site.)

2.4.2 Classical ergonomics

Classical ergonomics, also called "interface ergonomics". The interface referred to is the person / machine interface of controls and displays, and the principle contribution of the human factors expert is the improved design of dials and meters, control knobs and panel layout. The human factors expert's concerns can extend beyond the design of chairs, benches and machinery and to a limited extent the specification of the optimum ambient working environment.

The 'classical approach' began primarily with the design of military equipment, but now considers the design of items and workspaces in civilian contexts. Given this approach often takes a consultancy mode, advice is usually given in the form of principles, guidelines and standards. Such application of guidelines and prescriptions for design activity are limited by their lack of context-related specific advice. Design problem can only be considered with the "best" solution according to the experimental results without being able to predict either the likely consequences of deviations from that or the way it would change in other conditions. Classical ergonomists also face organizational problems: relegated to advising on final product, not full member of the design team. Often there are communication barriers between ergonomists and developers. Historically, this approach has run into difficulties as people see the

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ergonomist as having roots in the efficiency and time motion studies of Taylor and the Gilbreth's.

2.4.3 Error ergonomics

The is the study and explanation of human error in systems. The "zero defects" approach assumes that human error is the result of inadequate motivation, c.f. the examples of accidents and error attribution. This approach tends to results in campaigns for safety propaganda, e.g. oil rigs. These drives attempt to raise awareness and incentives for the workers. However, even in WW I, where there was a highly motivated work force, fatigue was a major problem.

Similarly, the "error data store" approach believes that human error is inevitable. This approach produces data banks of error probabilities for a variety of tasks executed under various conditions. Proposed solutions take the form of ways of designing systems in such a way as to minimize the occurrence and effects or errors. Therefore, it is necessary to predict the incidence and consequences of human errors in any given situation.

2.4.4 Systems ergonomics

This approach developed in the USA in the 1950's, and takes a more holistic approach to user-system dyad. The user and the system are seen as a single interacting system that is placed within a work context. Within this approach, system design involves parallel development of hardware and personnel issues, with training and selection issues considered. The ergonomist acts as a full member of the design team, working throughout the design cycle and involved in early and late design guidance. Therefore, in addition to the anthropometric, behavioral and cognitive considerations of the finished product itself, the human factors expert is involved in: (a) determining the required task functions (by activity and task analysis in conjunction with the consideration of the task requirements) and allocating the functions between the user and the system, (b) the design of personnel subsystems, and (c) the design of job descriptions and job support materials (e.g. manuals and training schemes).

The approach differs from user-centred design as the designers and human factors experts still view the user as just one part of the system, whereas user-centred design focuses more on the user's needs and perspective than those of the system, tasks and activities per se. In computer system development for example, a systems approach would consider the task from a "logical", "syntactic" perspective then the computer system implementation issues with a view to allocating function between the user and the computer system. A user-centred approach would consider the processing capabilities of the human user and analyze tasks from the perspective of the user.

2.4.5 Socio-technical Systems [Baxter]

The term socio-technical systems was originally coined by Emery and Trist (1960) to describe systems that involve a complex interaction between humans, machines, and the environmental aspects of the work system—something that is true of most systems in the workplace. The corollary of this definition is that all of these factors—people, machines and context—need to be taken into account when developing socio-technical systems using so-called socio-technical system design (STSD) methods, such as ETHICS

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(Effective Technical and Human Implementation of Computer-based Systems, Mumford, 1995)(Mumford, 1983; Mumford, 1995). In reality, these methods are more like guiding philosophies than the sorts of design methods that are usually associated with systems engineering (Mumford, 2006). In other words, the STSD methods tend to provide a process and a set of guiding principles (e.g., Cherns, 1987; Clegg, 2000), rather than a set of detailed steps that have to be followed.

From its inception in the period immediately after World War II, by what is now called The Tavistock Institute, until the present day there have been several attempts at applying the ideas of STSD, although these have not always been successful (e.g., see Mumford, 2006 for a critical review of the history of STSD methods). Early work in STSD focused mostly on manufacturing and production industries such as coal, textiles, and petrochemicals. The general aim was to investigate the organization of work, and see whether it could be made more humanistic. incorporating aspects such as the quality of working life. In other words the idea was a move away from the mechanistic view of work that is usually associated with Taylor’s principles of scientific management, which largely relied on the specialization of work and the division of labor.

The heyday of STSD was probably the 1970s. This was a time when there were labor shortages, and companies were keen to use all means available to keep their existing staff. This was also the period where more and more computer systems were being introduced into the workplace. Apart from the usual cultural and social reasons, companies could also see good business reasons for adopting socio-technical ideas. As just one of many such examples, Digital Equipment Corporation (DEC) had a family of expert systems that were developed using STSD (e.g., see Mumford & MacDonald, 1989) to support configuration and location of DEC VAX computers that saved the company tens of millions of dollars a year (Barker & O’Connor, 1989).

There was a downturn in the use of STSD in the 1980s and 1990s as lean production techniques and business process re-engineering approaches dominated system development. STSD is, however, still widely advocated in the field of health informatics for the development of health care applications (e.g., Whetton, 2005). Many medical systems are still never used because they introduce ways of working that conflict with other aspects of the user’s job, or they require changes to procedures that affect other people’s responsibilities. By focusing on the underlying work structure, STSD approaches facilitate the development of medical systems that are acceptable to the users (Berg, 1999, 2001; Berg & Toussaint, 2003).

Socio-technical ideas pervade a lot of thinking around information systems, although they may not always be explicitly referred to as such (Avgerou et al., 2004). The ideas appear in areas such as participatory design methods, computer supported cooperative work (CSCW) and ethnographic approaches to design.

2.4.6 Cognitive Ergonomics/Cognitive Systems Engineering [Baxter]

Cognitive ergonomics (also known as cognitive engineering or cognitive systems engineering (CSE)) originally developed in the 1970s and early 1980s (Hollnagel & Woods, 1983) and has continued to evolve since that period (Hollnagel & Woods, 2005; D. D. Woods & Hollnagel, 2006). It is a functional approach to the study and development of what practitioners usually call human-machine systems. Here, machine is taken to represent any artifact that is designed for a specific purpose. There are

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technological aspects to these systems, and these aspects are mainly of interest because of how they are used. These systems are always embedded in a socio-technical context because people are involved in the design, construction, testing and use of these systems. Although CSE practitioners regard all systems as socio-technical systems, they usually draw a distinction between the technological system, in which the technology plays the central role in determining what happens, and the organizational system, in which people mainly determine what happens.

A cognitive system is a system that can modify its behavior on the basis of experience so as to achieve specific anti-entropic needs. In other words, a cognitive system can control what it does. So most living organisms and some kinds of machines (or, more generally, artifacts) are cognitive systems. Organizations can be treated as cognitive systems in themselves; they can also be treated as artifacts because they are artifacts that have been designed for a particular purpose, even though they are of a social, rather than a physical nature.

The joint cognitive system is the basic unit of analysis in CSE, which emphasizes the central idea of co-agency. In other words the human and machine have to be considered together, rather than as separate entities linked by human-machine interaction. The focus is very much a functional one, based on what the JCS does and why, rather than how it does it.

In practice, CSE focuses on JCSs with one or more of the following characteristics:

• The functioning is non-trivial in that it requires more than a simple action to generate a response from the artifact. For more complex artifacts planning may be required.

• The functioning of the artifact is at least partly unpredictable (this can be down to issues of ambiguity in interface design, for example, which make it unclear what a particular widget may do).

• The artifact entails a dynamic process, such that the pace of events is not user-driven, thereby making time a scarce resource.

CSE is thus largely concerned with applications in complex dynamic domains, such as aviation, industrial process control, healthcare and so on. Studies of these domains are based around three identifiable, interleaved threads: coping with complexity; use of artifacts; and JCSs.

CSE starts with trying to understand the issue at hand, using observation of JCSs to try to understand the patterns of work. It then uses this understanding to guide the search to identify what would be useful to support the types of work that have been observed. These insights are then used as a basis for (innovative) design, in participation with others, to support the work and the processes of change.

2.4.7 User-Centered Design

User centered design (cf. Norman, 1988) involves focusing on the user's needs, carrying out an activity/task analysis as well as a general requirements analysis, carrying out early testing and evaluation and designing iteratively. As in the systems approach this has a broader focus than the other approaches, but here there is a greater focus on the user.

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2.4.8 Human-Centered Design

A number of tenets exist under Human Centered design. First, the introduction of a new system should focus on the organizational changes, user needs and demands together with the technological requirements. Second, the boundaries between which issues are defined as "technical" and "organizational" are not fixed and need to be negotiated. This has been incarnated as socio-technical design. Next, new applications of technology should be seen as the development of permanent support systems and not one-off products that finishes with implementation (i.e. the way in which technological change alters the organization needs to be considered). Humans should be seen as the most important facets of an information systems and should be 'designed in'. The people context of information systems must be studied and understood for it is clear that dimensions such as gender, race, class, power affect people's behavior with respect to technologies. Finally, design by doing, and establish user participative design.

2.4.9 Human-Computer Interaction

Human-computer interaction is interested in improving how people interact with computers. Initially this was based primarily on screens and keyboards. Later work looked at how mice and graphical user interfaces (GUIs) were important, and how to design them. Current work is expanding the definition in several ways. One way is to define users more broadly and to define different types of users (e.g., children, adults). Another way is to examine interfaces where the computer is less visible, such as embedded computer applications like RFI tags and GPS systems. Yet another way is to look at higher level of analyses, such as social impacts and supporting and encouraging social interaction.

2.4.10 Beyond Human- and User-centered Design

There are other related areas that study the user and study how the user can interact with technology; we hesitate to list them lest we have to define them! Further work will help them integrate and define themselves. With this list in hand, however, you should be able to place them with respect to each other, and to start to see their similarities and differences, and their relative strengths and weaknesses.

Some later chapters and the final chapter in particular will provide some future directions we think these fields will grow towards.

2.5 Products of studying the user

Whilst HF studies are aimed at evaluating particular equipment and work space layouts (e.g., kitchen layout, display design, work surface heights, chair design, computer interfaces, aircraft cockpit layouts and so on), a more general aim is to develop principles (list from Norman, 1988) and models (e.g., the Model Human Processor, Card, Moran, & Newell, 1983) about how people interact with their environment and how that interaction affects their behavior. These principles can be used to derive performance predictions for the development of design guidelines (an example from Newman and Lamming, 1994) and legally enforceable standards (an example from Pheasant, for more information about different organizations that deal with standards) The evaluation,

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analysis and synthesis techniques are all methods that are also a product of human factors.

Some methods will be considered in the third part of this book. These include performance analysis, both analytic and empirical; iterative design; formative and summative evaluation using many different methods and from many different theoretical start points. Of course, any analysis that is carried out makes assumptions about what is valid as data and what level of analysis is appropriate. For example, someone with a strongly cognitive outlook will centralize the individual user’s viewpoint (e.g., as expressed by Blandford & Young, 1996; Kieras, 2003; and Card, Moran, & Newell, 1983), whilst someone with a more socio-technical outlook will focus more on the social and technology interactions in which work is carried out by the users (e.g., Clegg, 2000). Some models attempt to model multiple levels, cognitive, technological, and social (e.g., Barnard & May, 1993; Barnard, May, Duke, & Duce, 2000).

2.5.1 Application of Models, Principles, Guidelines, and Standards to design (shared representations)

Fill this in on “shared representation”

2.5.2 Usability: But what is it? (Dependability engineering)

The ultimate goal of quality must be that of fitness for purpose, although the criteria for determining whether this is achieved must be problem dependent, domain dependent and context dependent. Functionality, usability, and learnability are the issues, but are defined in different areas and by different authors.

Often functionality, what something does, is the first thing to be considered and some consideration of the usability issues is sometimes tacked on at the end. This can lead to poorly designed artifacts that are hard to use, but that offer new functionality. Sometimes, this is enough. Sometimes, it is not. Often, with more thoughtful design, one can have both.

Usability issues need to be considered with respect to the task that is being carried out and the human operator's capabilities. This kind of analysis leads us to reassess what is meant by "human error" and why accidents occur.

Learnability is how easy the system is to learn. This is affected by how complex it is, and also how similar it is to other systems that the users know. How similar it is to previous systems can also be important, as other users may be able to help novice with new systems if the are similar to previous systems, and concsultants and teachers may be available if they are similar.

Usability can be defined in several ways, and several people have tried to explain what it is so that designs can be evaluated. We will note a few here. Considering the quality of system and software design: There are many factors, but in addition to the three noted above, we can also note: reliability, efficiency, maintainability, and learnability, as well as testability, portability, and reusability.

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Rel iabi l ity is concerned with the dynamic properties of the eventual system and involves the designer in making predictions about behavioral issues. We need to know if the system is going to be complete (in the sense that it will be able to handle all combinations of events and system states), consistent (in that its behavior will be as expected and will be repeatable, regardless of the overall system loading at any time, and across components of the system) and robust (when faced with component failure or some similar conflict (for example, if the printer used for logging data in a chemical process-control plant fails for some reason, this should not be able to 'hang' the whole system but should be handled according to the philosophy summed up in the term graceful degradation.

Effic iency of a system: can be measured through the use of resources such as processor time, memory, network access, system facilities, disk space and so on. Often the most cited by programmers. For good reasons because it ensures that systems work fast and don't frustrate users. But don't be mistaken, the concern with efficiency is more often about the ego of the programmer than about the poor end users.

It is a relative concept in that one system can be evaluated as more efficient than another in terms of some parameter such as processor use, but there is no absolute scale on which to specify an optimum efficiency as soon as multiple criteria are allowed, which is nearly always the case in the real world. In the early days of computers, when programs were small and computer time was relatively expensive, efficiency of computer time was considered to be of paramount importance, and it probably was. With the better machines of today, the designer needs to consider the effects of choices upon all resources. The HF professional most often defends the user's resources, including their motivation.

Maintainabil ity is how easy a system is to maintain and upgrade. As systems get larger and more costly, the need for a life-long time in service increases in parallel. To help achieve this, designs must allow for future modification. Designers needs to provide future maintainers with mental models of the system so they can gain a clear understanding (Littman et al 1987). Development of modular designs....BUT....

As systems get larger and more complex, the problems of ensuring reliability also escalate. For safety critical systems where this factor is paramount, various techniques have been developed to help overcome limitations in design and implementation techniques. For example, in a system used in a fly-by-wire aircraft in which the control surfaces are managed by computer links rather than by direct hydraulic controls, the implementation will be by means of multiple computers, each programmed by a separate development team and tested independently any operational request to the control system will then be processed in parallel by all the computers and only if they concur with the requested operation to be performed.

Ravden et al specify the following usability criteria: visual clarity

consistency

informative feedback

explicitness

appropriate functionality

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36 August 31, 2010

flexibility and control

error prevention and control

user guidance and support

Eason: Usability is not determined by just one or two constituents, but is influenced by a number of factors. These factors do not simply and directly affect usability, but interact with one another in sometimes complex ways. Eason (1984) has suggested a series of concepts that explain what these variables may be: system function-task match, task characteristics, user characteristics, are independent variables that lead to the dependent variables of user reaction, scope of use (restricted, partial, distant, constant).

Eason offers the following definition of usability: the "major indicator of usability is whether a system or facility is used". However, this is patently not the case as many devices that are used are hard to use. A more operational definition of usability would be ISO (International Standards Organisation ) "the usability of a product is the degree to which specific users can achieve specific goals within a particular environment; effectively efficiently comfortably and in an acceptable manner."

The ETSI (European Telecommunications Standards Inst) considers two kinds of usability dimensions, those linked to performance and those related to attitude, where performance is measured objectively and attitude represents subjective dimensions (ETSI, 1991).

Shackel (1991) maintains the distinction between performance and attitudinal dimensions, but he defines four distinguishable and quantifiable dimensions that may sensibly assume varying degrees of importance in different systems: effectiveness, learnability, flexibility and attitude. These dimensions are not mutually exclusive in the sense that measures of effectiveness, for example, can at the same time also give some indication of system learnability. However, they provide a good starting point.

Booth (1989) says that usability is usefulness, effectiveness and easy of use, learnability, attitude and likeability. A useful system is one that helps users to achieve their goals.

Most important concepts remain: FUNCTIONALITY, USABILITY, LEARNABILITY.

2.6 Summary

User-centered design draws on multiple sources of knowledge to support creating systems that are based on user’s abilities, capabilities, and task. This book cannot survey all of them, but can provide you with an initial set of important theories and results for informing your design. This book can provide you with a framework for organizing your existing and future knowledge, and provide you with some initial methods for applying this knowledge to design, although its emphasis is not on design per se and it does not discuss design until it has presented some information on the material you are designing with, for, and around, humans.

Some of the conclusions that we wish you to take away from this chapter are presented in Table 2-1.

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Table 2-1. Summary lessons about the areas of knowledge that make up human-centered design.

• Concerned with fitting the environment to the person.

• Often perceived (esp. historically) as a discipline born of crisis, human factors in particular.

• Can be seen as a human-centred design philosophy.

• Bodies of knowledge about human behavior in systems.

• Interdisciplinary, multidisciplinary, and international.

Later chapters will explore issues related to design. These issues are previewed in Table 2-2.

Table 2-2. Summary lessons about applications to design. • There are constraints and trade-offs involved in design. Making these trade-

offs requires understanding the properties of the materials (e.g., users and technology).

• Applications to design are complemented with consideration of other system issues, including selection and training.

• Design decisions have consequences for the user's behavior/performance.

• Latent errors in the design are most often manifested at the 'sharp end' of work activities (that is, when a user does their task).

• "Errors" and "mistakes" by users may often be circumvented by good design.

• Often design decisions are made on the basis of perceived need and market forces that drive a focus on functionality and not usability and learnability.

• In many cases, the space of design options is enormous, although a number of factors reduce the design space, for example, standards (legal issues), cost, and time constraints.

• Functionality, learnability, usability (objective and subjective measures) all have a role in system evaluation.

• Designers must look at how systems are used and how they are perceived in order to help design.

• well formed but approximate theories of cognition and social cognition are necessary for design.

• human adaptability is incredible, BUT it is not "free", it requires time to adapt, consumes mental and physical resources.

• The role of anthropometrics, behavioral issues, cognitive issues, and social context issues.

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38 August 31, 2010

2.7 Glossary of terms

If you don't recognize these terms, you should go back and reread the section. As a study aid, we have deliberately left room for notes here, and do not spell them out.

Human-computer interaction, cognitive ergonomics, human factors, ergonomics, Hawthorne effect

2.8 Other resources

Here, we note some further books and online resources. We expect that any given student is likely to read one of the references per chapter either as additional assigned reading or as an optional part of a course.

Shachtman, T. (2002). Laboratory warriors: How Allied science and technology tipped the

balance in World War II. New York, NY: HarperCollins. An interesting history book on operations research and the role that the study of users can play in operations research.

The family life of the Gilbreths, some of the first human factors researchers is chronicled in several books and in a 1950 MGM movie. The humour partly arises from taking issues in human factors too seriously or without sympathy to the context, deliberately and also inadvertently. Online book sellers can provide you with various editions of Cheaper by the dozen, and Belles on their toes, and The one best way (a more serious reflection).

2.9 Exercises

We will be using as running examples

a. designing a wireless personal digital assistant,

b. online business services, such as online training, online banking, and web stores,

c. a web site for a university department, which will support multiple tasks from providing contact details to disseminating technical reports to receiving applications and providing online instruction.

Exercise 2.1

Consider a wireless personal digital assistant (PDA), either a specific one or a composite one and consider the human factors of using it. What are the issues that each field of HCI, human factors, and cognitive ergonomics address?

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39 August 31, 2010

Write short notes (about one side of a page, total) noting the issues on these three types of analyses (ABCS).

Exercise 2.2

Pick a company’s web site or a university department’s web site. Summarize in note form how each of the major fields noted in this chapter would analyze it and its users. Note what would be the outputs and typical recommendations. Which approach would you prefer to apply to your own web site? Note the relative value and the absolute value of each. That is, which gives the best results for the amount of inputs, and which gives the best value without regard to cost.