The human factors toolkit
4.1 Introduction
Man has dominated planet Earth for thousands of years, and we have only to look at our environment to see all the things that humans have created. In an ideal world, all the objects used by us should have been designed with this in mind. For example, the tables, the chairs, the lighting in my current surroundings, should all meet my physical and work needs in terms of their design. Not all objects fall into this category, namely, those pieces that have been created to fulfil our aesthetic needs, e.g. objets d’art, paintings, pottery, sculptures, etc. A simple classification, therefore, for objects in the world is that they fall into three categories: those belonging to the natural world about whose design we can do little (although biological advances are now challenging this view), those objects that we create for our aesthetic needs, and those that are developed for us to use. It is the third group that is of interest here. The aim of this chapter is to provide a broad overview of the issues surrounding human factors methods and tools.
In theory, all the objects in the built world should have been carefully designed for the human user. In practice, this is not the case and we are surrounded by poor design. As an example, take domestic products. We have microwave ovens that are difficult to programme, we have cooker hobs with no obvious matching between the controls and the burners, and clock radios and video recorders with banks of identical switches. The end-result is that we make mistakes, become irritated and do not use the range of functionality offered by most domestic appliances. But does this matter?
For most of us, it is of minor inconvenience, and often with extra effort or paper aids
we can manage to achieve our desired goals. Certainly, in the past in industry, poor design was not considered a priority.
In the heavy industries in the late 19th century, the human was often the expendable
‘part’ in the system. There was little need to ensure the design of the equipment was suited to the worker. If a person was injured or killed, there was usually another individual to take their place. Since a lot of the work was unskilled, ‘replacement’
workers quickly learned how to do the manual jobs. However, the situation began to change around the time of the Second World War. The introduction of more advanced technologies, e.g. radar screens, cockpit controls and displays, were found to be problematic for the operators. Many were having difficulties learning to use the equipment and were making mistakes. This might not have mattered in peacetime, but skilled personnel were at a premium during the war. There was little time for training; hence, it was vital to preserve the working population. Consequently, there was a realisation that it was no longer possible to ignore the needs and capabilities of the users when designing these more advanced technologies. In recognition of this, the UK Ergonomics Society and the US Human Factors Society were created in the late 1940s.
Ergonomics derives from the word ‘erg’ meaning work, and ‘nomos’ meaning science; hence, it is the study of the science of work. The terms ergonomics and human factors are often taken as synonymous, although there is some evidence that ergonomics has its origins more in the consideration of the physiological aspects of the human, while human factors focuses more on the psychological element. Both societies have now celebrated their 50th anniversaries, and in conjunction with the International Ergonomics Association (IEA) continue to thrive and to grow. Today, in the developed world, there is a growing awareness of the benefits to be accrued from taking the human user into account in the design process. However, designing for humans is not easy, and further, it comes with a cost.
There are a number of reasons why it is not easy to design for humans and some will be briefly considered here. The first issue concerns adaptation – even if the design is poor or inadequate, humans will adapt to it. Take, for example, the QWERTY key- board designed in the 1860s as part of the Victorian typewriter, and still in very wide use today. (Ironically, it is now appearing in miniaturised form on Personal Digital Assistants [PDAs].) Yet, this design has been recognised by many researchers as not being the optimum keyboard layout (see [1]). Another issue concerns our creativity.
Humans are creative and will think of ways to accommodate poor design, e.g. placing beer pump labels on control room panels in order to differentiate specific switches from among the banks of identical ones. A final point is variability. There is a lot of variability in human performance, e.g. reaction time measures can show more intra- variation, i.e. within the person, than inter-variation, i.e. between people. A further compounding factor relates to user expectations; often, prospective users are not sure what they want from a product. Take, for example, white goods. Most have a wide range of functions: washing machines, for example, have perhaps 20 different pro- grammes. However, studies with users indicate that most only use two programmes – a fast and a slow wash. What users say they would like to use is different from what they actually use. As a result, designing for humans is not straightforward.
A further issue relates to the costs of design. When designing a product or a system, there are certain personnel involved in the design process without whom the object could not be created, e.g. software writers, design engineers, hardware and electronic specialists, etc. The design team may view the human factors engineer as a ‘bit of a luxury’ since the product can be designed without them. (A frequently heard comment from engineers concerns the fact that they are human, so they can use themselves as the user model!) Pheasant ([2], p. 10) summed up this point and others in his five fundamental fallacies of design. These illustrate some of the misconceptions concerning ergonomics and design, and are given in Table 4.1.
Moreover, adding human factors personnel to the design team inflates the costs and the development time. On the surface, there appears little incentive to include human factors. However, there is evidence that there are cost benefits to be attained from the implementation of human factors. Bias and Meyhew [3] in their book on
‘cost-justifying usability’ provided many examples where incorporating ergonomic methods into the design process resulted in significant savings. Stanton and Young [4]
took this a step further by factoring the reliability and validity of various ergonomic methods into the cost-benefit analyses. A detailed discussion on the cost-benefits of human factors is given in Chapter 1 of this book.
In summary, human factors (or ergonomics) is all about design. But there is little point in designing something for humans to use without carrying out some form of assessment that this objective has actually been met. Consideration of how to assess and evaluate design provides the focus of the current chapter, namely, an overview of the methods, grouped together under the umbrella of the human factors toolkit, which can be employed for assessing the design of products and systems.
Table 4.1 The five fundamental fallacies (reprinted with permission from Taylor &
Francis)
No. 1 This design is satisfactory for me – it will, therefore, be satisfactory for everybody else. (Fallacy – designing for oneself will be fine for everyone else.) No. 2 This design is satisfactory for the average person – it will, therefore, be satisfactory
for everybody else. (Fallacy – designing for the average will be fine for everyone.) No. 3 The variability of human beings is so great that it cannot possibly be catered for in any design – but since people are wonderfully adaptable it does not matter anyway.
(Fallacy – the population varies greatly and people adapt, so why bother to consider design at all?)
No. 4 Ergonomics is expensive and since products are actually purchased on appearance and styling, ergonomic considerations may conveniently be ignored.
(Fallacy – ergonomics is expensive and people are more interested in how things look, so need we bother?)
No. 5 Ergonomics is an excellent idea. I always design things with ergonomics in mind – but I do it intuitively and rely on my common sense so I do not need tables of data or empirical studies. (Fallacy – designing for humans is intuitive and common sense, so why bother with ergonomics?)