Designing for Humans

Jan Noyes

• Publisher: Psychology Press
• Year: 2002
• Print ISBN: 9780415227223
• eBook ISBN: 9781134588107
• Topic: Psychology
• Subtopic: Applied Psychology
• Index: Psychology

Nature aside, the world in which we live should be designed for us, from everyday products like scissors and chairs to complex systems in avionics, medicine and nuclear power applications. Now more than ever, technological advances continue to increase the range and complexity of tasks that people have to perform. As a discipline, human factors psychology (ergonomics) therefore has an increasingly important role to play in ensuring that the human user's physical characteristics, cognitive abilities and social needs are taken into account in the development, implementation and operation of products and systems. In this book, Jan Noyes provides a comprehensive and up-to-date overview of human-machine interaction and the design of environments at work. Focusing on topics relevant to user-centred design, she includes coverage of the capabilities and limitations of humans, human-machine interactions, work environments, and organizational issues. Health and safety issues underpin a large amount of work on the human factors of design, and these are addressed fully throughout the book. Each chapter includes case studies that demonstrate the real-world relevance of the points being made and concludes with a list of key points. Although aimed primarily at advanced undergraduates, postgraduates and researchers in organizational and occupational psychology, this book will also be of relevance to students on engineering, computing and applied psychology/human factors programmes.

1 Human Factors

Life was simple before World War II. After that, we had systems.

Grace Hopper, Developer of the COBOL computer language, 1987

‘Human Factors’ is one of those nebulous expressions that is frequently used in everyday life, and in this sense defining it is not easy. Human factors are omnipresent in that we are all aware of the influence of humans in whatever we do or attempt to do and, when taken literally, the term conveys little precise meaning to the reader or listener. However, for one group of psychologists, this term has a very specific definition and meaning. It refers to the area of work concerned with the interaction of humans with machines, and the many implications arising from this. To differentiate the more general meaning of human factors, i.e. ‘aspects relating to the nature of people’ (Edwards and Edwards, 1990:7), the term will be given capital letters when referring to the discipline.

Origins

The origins of Human Factors are often quoted as residing in a study of shovel design carried out in the late 1890s. The study was conducted by the Quaker engineer Frederick W.Taylor, who is primarily remembered for his principles of scientific management (see biographies by Kakar, 1970; Nelson, 1980; Zalesnik, 1966). In 1878 Taylor began work as a foreman at Bethlehem Steel Works in the US eventually becoming promoted to chief engineer. During this time, he had begun to take a keen interest in the best way to do a job in order to ensure the workers’ productivity (see Taylor, 1911). Taylor studied the actions of the workers, their use of equipment and their rest periods, and related this to levels of productivity. He began by collecting baseline data, i.e. information about the workers, their tools and the materials (iron ore and steel) to be moved. Anywhere between 400 and 600 full-time workers brought their own shovels to work and used them to shift different types of material. Shovel loads varied from 3.5 pounds for coal to 38 pounds for iron ore—pounds being the imperial measure in use at this time—equivalent to 1.6 kilograms for coal to 17.2 kilograms for iron ore. Taylor’s optimal shovel load was 9 kilograms; this is in the middle of the range of 5–11 kilograms specified by Frievalds (1986) in a review of the ergonomics of spade design and shovelling. Once Taylor had collected his baseline information, he began the second phase of his study. This was an experimental investigation in which two men moved materials with an array of shovels that decreased in size. Taylor concluded that the best shovel load was one weighing around 21 pounds (9.5 kilograms), and that different sized shovels would be needed to shift the various materials. He used this information to persuade the management at the steel works to purchase a range of shovels for different people and various shovelling tasks. Moreover, he kept records of individual worker productivity and provided training for those who were not meeting targets. Over a 3-year period, the costs of shovelling fell by a half. However, this was probably in part due to the fact that the number of shovellers fell to 140. Taylor’s now well-known shovelling study comprised one of the first ‘time and motion’ studies (Taylor, 1903). He found that through these time and motion studies he could break jobs down into smaller, well-defined tasks and then devise a better, more efficient way to perform the same jobs, i.e. increase the worker’s productivity. Taylor also generalised from one situation to another. For example, he carried out about 40,000 experiments to find the best ways of cutting metal (Taylor, 1907). Although Taylor’s early work at the Midvale Steel Company focused on how workers managed their jobs, i.e. the time and motion studies, his later interest concerned managing workers. He was particularly interested in the piecework method of production and payment. The principles of scientific management for which Taylor is probably best remembered emanated primarily from this later work. Taylor’s primary interest was in increasing productivity and, because of this, it has been argued that Taylor’s motives were not entirely for the benefit of the workers, i.e. human-centred (Ryan and Smith, 1954). Hence, many workers considered ‘Taylorism’ to be a form of exploitation and, in 1912, Taylor’s system of shop management was investigated by the US House of Representatives (Taylor, 1947). In his defence, Taylor did denounce the exploitation of workers at a public forum in 1916 (Berry and Houston, 1993).

The principled approach of Taylor’s early work, i.e. systematic and empirical observation of workers in time and motion studies, was continued by Frank and Lillian Gilbreth—a husband and wife team—who replicated some of Taylor’s early work (although they had no direct contact with Taylor) by conducting time and motion studies of bricklayers. Frank Gilbreth began his working career as a bricklayer’s apprentice in 1885. He was promoted rapidly and subsequently became interested in work methods. Soon, he was studying how workers carried out building tasks in the construction industry. One particular study considered the actions of bricklayers, and experimented with modifying the scaffolding for the picking up of bricks, techniques for sorting and stacking the bricks before laying, and methods of bricklaying (Gilbreth and Gilbreth, 1921). The Gilbreths found that the development of a new method of laying bricks could decrease the number of actions required to lay one brick from eighteen to less than five. Consequently, they found that they could improve the workers’ productivity by increasing the number of bricks laid from 120 per hour to 350 per hour. The Gilbreths also refined the techniques for observing human behaviour with the development of a motion picture camera that time-marked the film. By 1917, they had developed a technique for recording the time, speed and acceleration of movements (Barnes, 1940). This and other work comprised a significant step forward in the study of human performance. For example, their research with hospital surgical teams has had long-lasting effects in the procedures associated with instrument selection. The Gilbreths observed that surgeons were spending a lot of their operating time looking for the required instrument and so introduced the procedure whereby the accompanying nurse selected and orientated the tools for the surgeons. Apart from having a large family— Lillian Gilbreth gained some notoriety as the key figure in Cheaper by the Dozen, a story of a woman with a PhD in psychology who combined research with a houseful of children—their other ‘claim to fame’ was generating the term ‘therblig’ for a (very small) unit of work (Konz, 1990). This was an anagram of their surname and it hardly needs to be stated that it has not become common usage. Like the reasons for Taylor’s work, the motives behind some of the Gilbreth’s studies must be questioned because their primary interest was not the welfare of the workers, but how to increase productivity. However, this perspective needs to be viewed within the context of the times in which they lived. Towards the end of the nineteenth century and the industrial revolution, the heavy industries (iron, coal, steel) were flourishing and there was no shortage of work or people to carry out what was predominantly manual work (Flinn, 1966). In many ways, the human was the expendable part of the system—if anyone dropped out for whatever reason (illness, injury, even death), there was usually another person waiting to take their place. This situation was exacerbated in the early part of the 1900s when recession hit the economies of the western world and work was in short supply for manual labourers. Hence, it is reasonable to conclude that consideration of the human (and their needs and requirements for satisfaction) took a low priority in the workplace.

In the 1920s, Elton Mayo and F.J.Roethlisberger conducted the Hawthorne studies (Roethlisberger and Dickson, 1939). They were named this because the work was carried out at the Hawthorne Works of the Bell System’s Western Electric Company in the US. Between 1924 and 1933, Mayo and Roethlisberger looked at a number of issues relating to human behaviour in the workplace. The so-called Hawthorne effect emanated from the now famous illumination experiments and the bank wiring observation room study. Briefly, the illumination experiments considered workers’ productivity under different levels of lighting. It was hypothesised that higher levels of illumination would result in greater output, and indeed they found that this was the case. However, lowering the levels of illuminations also had the same effect, i.e. productivity improved. The researchers had come across a phenomenon that was unrelated to illumination levels; namely, attention and interest from the researchers had apparently motivated the workers to greater output. The bank wiring assembly room study demonstrated a similar effect. Mayo and Roethlisberger noticed that when a new worker joined the bank wiring assembly room their output was high, but after a few weeks it dropped. As the workers were paid according to the amount of equipment they assembled, this observation appeared puzzling. It was subsequently noticed that the more experienced workers were putting pressure on the new individual to conform to group norms of productivity— the established group was concerned that higher productivity would result in management shifting the base rates. This would result in them having to work harder to achieve the equivalent payment. Like the illumination experiments, this finding underlined the importance of interpersonal relationships in the workplace and reinforced the complexity of workplace management in that workers did not work solely for financial reward (see Parsons, 1974; 1990). The Hawthorne studies also indicated the complexity of relating productivity to efficiency in that there was no simple linear relationship (Blum and Naylor, 1968), although some have argued that the research methods were flawed (Bramel and Friend, 1981). For a detailed account of the Hawthorne studies, see Gillespie (1991).

In the UK, a major milestone was the formation of the Health of Munitions Workers’ Committee in 1915. This development was in response to the number of problems relating to people that had been experienced in the munitions factories at the start of World War I when it was important to the war effort that work was carried out efficiently and productivity was high. At the end of the war, the Committee was reconstituted as the Industrial Fatigue Research Board (IFRB). As the name suggests, its primary interest was to consider issues associated with fatigue as well as determinants of productivity in the workplace such as job rotation. In 1929, the IFRB became the Industrial Health Research Board and, correspondingly, its scope was broadened to consider the health of workers per se within the context of industrial efficiency. The Board comprised psychologists, engineers and medics who worked on a wide range of problems relating to job design, the working environment, selection and training. A further significant development was the formation of the National Institute of Industrial Psychology that focused on selection, recruitment and training issues. In fact, testing, selection and training issues had already become established as the primary area of interest for the applied psychologists. As Berry and Houston (1993) pointed out, the 1935 issues of Psychological Abstracts provide evidence of a continuing emphasis on vocational topics.

It can be seen that formal interest in the worker was gradually gathering momentum both in the UK and US with the formation of a number of committees and the execution of some large-scale research studies. This situation was about to be accelerated by the outbreak of World War II and the rapid development and implementation of new ideas, activities and technologies. It was quickly realised that no amount of training of carefully selected personnel could ensure good human-machine interactions. The approach of ‘FMJ—fitting the man to the job’, i.e. selecting workers for the job, was soon to be replaced by the approach of FJM—fitting the job to the man’ (Rodger and Cavanagh, 1962).

World War II

One of the significant differences between World War I and World War II was that the former was fought mainly on the land and at sea, rather than in the air. For World War II to involve air battles, a number of rapid technological developments had taken place both prior to and during the war. This was certainly the case in cockpit design, where developments could be traced back to the success of getting the first aeroplanes airborne by the Wright brothers in 1909. One of the outcomes of the war was that equipment had to be designed and implemented urgently without ample opportunity for testing. This was especially the case with the human element, which was often the neglected component in system design. Subsequently, a number of mistakes were made. For example, radar operators were placed on 8-hour shifts until it was noticed that they were missing a large number of targets after a fairly short time (Mackworth, 1948, 1950). We now know from work on vigilance that in some monitoring situations detection performance declines after the first 20–30 minutes, and it is generally hard for people to maintain good monitoring skills, especially if searching for a low frequency target. Humans are not good ‘monitors’ and tasks need to be designed, whenever possible, to take this into account. This is especially the case when we are doing nothing but monitoring (Warm et al., 1996).

Another example of hasty design concerns the Douglas escape hatch that allowed parachutists to exit the aircraft when airborne. It was not realised until the aircraft was actually flying and the parachutist was attempting to exit via the hatch that the designers had not allowed enough clearance room. The size of the aircraft hatch had been designed to accommodate basic human dimensions and had not taken into account the extra width needed because of the parachute. Hence, the person could leave on his or her own but not with the parachute!

A third example concerns the seat design for anti-aircraft gunners onboard ships. These personnel were given standard car-like seats that were fine when sighting aircraft in the distance close to the horizon, but not when trying to locate aircraft directly overhead. The problem was that it was not possible to adjust the seats and tilt them backwards as and when appropriate.

A final example of poorly designed aircraft systems could be found on the B-52 bombers. On some aircraft, similar-looking controls operating the landing gear and steering flaps were placed next to each other. As a result, several B-52s landed on their ‘bellies’ because the pilots had believed that they had operated the landing gear control when they were actually operating the steering flaps.

Although these design errors may seem obvious, even amusing now, it did mean that people began to question the need for better designs and research into human-machine interaction. Psychologists were brought into direct contact with Human Factors issues, and one individual who made a significant contribution to this work was Sir Frederic Bartlett. He was responsible for building a simulator of the Spitfire aircraft cockpit in order to investigate the effects of stress and fatigue on pilot behaviour. The shift of attention from machine to human had occurred and the area of Human Factors was born.

Birth of Human Factors

It is never easy to date the exact moment that an organisation is formed. But, shortly after World War II, several groups of individuals around the world began to discuss the need to set up professional bodies on Human Factors. In the UK, an interdisciplinary group (the ‘Human Performance Group’) was formed at a meeting held at the British Admiralty in July 1949. It should be noted that there is a discrepancy here in terms of the date of the actual meeting in Room 1101 of the Admiralty building at Queen Anne’s Mansions. Some sources date it as 8 July and others as 12 July—there may of course have been two meetings of the working group! The following year, this group formed the Ergonomics Research Society, which is now the UK Ergonomics Society (Edholm and Murrell, 1973). At about the same time, a group in the US was laying the foundations of the Human Factors Society. At the end of the war in 1945 a number of engineering psychology laboratories had been established in the US by the armed forces. These led to the formation of the Human Factors Society in 1957. In the same year, the organisation of Division 21 (Society of Engineering Psychology) of the American Psychological Association (APA) took place; the APA itself had been founded in 1892. 1957 was also the year in which the UK journal Ergonomics was launched. Two other significant publication milestones were the first article on human engineering in the Journal of Applied Psychology and the publishing of one of the first books on Human Factors in 1949 by Chapanis, Garner and Morgan. Ten years later, in 1959, the International Ergonomics Association (IEA) was formed with the intention of linking the various Human Factors and ergonomics societies and groups around the world (Chapanis, 1990). In 1964, the Ergonomics Society of Australia and New Zealand (ESANZ) was formed (see Welford, 1976a). As evidence of the growth of ergonomics, the IEA professional body now has thirty-six member societies around the world (Shackel, 1997).

It should be noted that the UK and Australasian communities favour the term ‘ergonomics’—derived from the Greek ‘ergon’ meaning work and ‘nomos’ meaning natural laws. The word, or variations of it, is now used in many parts of the world, e.g. ‘ergonomie’ in France and Holland, and ‘ergonomia’ in Hungary and Brazil. Taken literally, the word ergonomics means ‘the customs, habits or laws of work’. It was ‘coined to denote an approach to the problems of human work and control operations which came into prominence during the second world war in relation to equipment for the fighting services’ (Editorial, 1957:1). The word is not new, having been used by the Polish scholar, Wojciech Jastrzebowski in his now classic 1857 treatise An Outline of Ergonomics, Or the Science of Work (Karwowski, 1991). Jastrzebowski’s work was republished as a Special Commemorative Edition by the Central Institute for Labour Protection (Koradecka, 2000). Post-war, initial reaction to the word was not positive and there was some resistance to it. To quote Welford (1976a:277), people thought it was ‘ugly, incomprehensible, and easily confused with economics, and it took considerable persuasion to obtain the agreement of the publishers for its use as the title of a journal’.

The difference between ergonomics and Human Factors is not obvious, and indeed it could be argued that the terms are synonymous, i.e. one side of the Atlantic favoured ergonomics and the other, Human Factors. In the past, the term ergonomics has often been used in the context of ‘knobs and dials’ ergonomics, suggesting a narrower definition than Human Factors, which could be thought to encompass any aspect involving humans in their work (Hawkins, 1993). Another view is that ergonomics is more concerned with the physical aspects of human work (Grandjean, 1988). Indeed, it is generally thought that ergonomics was grounded in the biological sciences whereas Human Factors is grounded in psychology. A perusal of the first volume of Ergonomics would probably support this, with papers on fatigue, stress, physiological aspects of human-machine interaction, training, effects of environment (noise, light, flicker, heat, vibration). Interestingly, the situation has become less clear. On the 1 January 1993 the Human Factors Society adopted the word ergonomics in its title, i.e. the Human Factors and Ergonomics Society (Editorial, 1993). This followed many months of discussion that indicated a reluctance to abandon the term ‘Human Factors’ while there was some support for the more technical sounding term ‘Ergonomics’. Some discussants considered that the latter was a subclass of Human Factors while others held the reverse opinion. However, there was considerable support for the view that the terms were synonymous. Sanders and McCormick (1987) supported the viewpoint that the terms were synonymous by stating that any distinctions were arbitrary and have not been maintained. To some extent, the Canadian Society ‘solved’ the problem by using ‘Human Factors’ in their English name and ‘ergonomie’ in its French version. Other phrases used to describe this area are ‘industrial psychology’, ‘human psychology’, ‘I/O (input/output) psychology’ and ‘engineering psychology’. The term ‘human engineering’ has also been employed, but there is a concern here of confusion with exercises in genetic intervention (Edwards and Edwards, 1990). It can be seen that many of these phrases include the word ‘psychology’ and, hence, could be thought of as disciplines within psychology. In the UK, the last term has gained some prominence with the formation of a Special Interest Group on engineering psychology by the British Psychological Society and the launch of a new biennial conference on Engineering Psychology and Cognitive Ergonomics. Table 1.1 lists the topics covered in the first conference in 1996. In the US, a new journal—The International Journal of Cognitive Ergonomics—was launched in 1997. Wickens (1992) argued that the goal of engineering psychology was understanding human performance within the context of designing systems whereas Human Factors was more concerned with applying the findings on understanding human performance to the de...

Table of contents

• Cover Page
• Title Page
• Copyright Page
• Tables
• Figures
• Preface
• Acknowledgements
• 1 Human Factors
• 2 Humans: capabilities and limitations
• 3 Human-machine interaction
• 4 Work environments
• 5 Organisational issues
• 6 Occupational health
• 7 Safety
• Epilogue
• References
• Annex: The British Psychological Society Occupational Psychology syllabus, year 2000