ABSTRACT
Engineering is concerned with improving products from the point of view of mechanical and electrical design, and psychology is concerned with the study of the mind and behaviour. Human factors and ergonomics are concerned with adapting products to people , based upon their physiological and psychological capacities and limitations (Blum, 1952 ) , the objective being to improve overall system performance (involving human and product elements) . As Sanders and McCormick ( 1987) put it, 'it is easier to bend metal than twist arms ' , by which they mean that the design of the device to prevent errors is likely to be more successful than telling people not to make errors when using a device. The overall objectives of ergonomics and human factors are to optimise the effectiveness and efficiency with which human activities are conducted as well as to improve the general quality of life through 'increased safety , reduced fatigue and stress, increased comfort [and] . . . satisfaction. ' (Sanders and McCormick, 1992, p. 4) . It is difficult to delineate the genesis of human factors and ergonomics , but both can be traced back to a general interest in problems at munitions factories during the First World War (Oborne, 1982) . Machines that were designed to be operated by men seemed to have production-related problems when operated by women. These difficulties were resolved when it was realised that the problems were related to equipment design rather than the people operating them, i.e. they were designed to be operated by men and not women. The misreading of altimeters by pilots in the Second World War stimulated further interest in human factors and ergonomics. A study by Grether ( 1949) illustrated that not only did pilots take over 7 seconds to interpret the traditional three-needle altimeter (where the three pointers read
tens of thousands, thousands and hundreds of feet respectively) but also that nearly 1 2 per cent of the readings contained errors of 1 000 feet or more. Grether showed conclusively that superior designs could dramatically reduce both reading time and error rate. This study, perhaps more than any other, indicates the importance of psychology in the design of devices . Despite this evidence, it is sometimes difficult to gain acceptance from the engineering community and to change design, as the following quote from an accident report in 1958 (some nine years after Grether's original study) shows :
The terms 'human factors ' and 'ergonomics ' will be used interchangeably throughout this book. This is not meant to confuse the reader, rather it reflects that they are synonymous . The Human Factors Society in the USA has recently changed its name to The Human Factors and Ergonomics Society in recogni tion of this. Although the origin of the discipline is in workplace domains , the subject has expanded to cover all manner of human interaction with technologi cal artefacts , including consumer products.
