Search

Affective or pleasurable appreciation in design is nothing new. Affect is what we admit to when we buy clothes, admire beautiful objects, or select a birthday card. But it is a fairly new area in r...

This paper is the IEA Presidential Address to the 1997 IEA Triennial Congress in Tampere, Finland. The evolution of ergonomics prior to and after the foundation of the International Ergonomics Association in 1957 is reviewed. Ergonomics has broadened from considering work activities to include all types of human activities. The recent introduction of computers has changed many of the premises for work and leisure activities, and cognitive ergonomics is now as important as the ‘biological’ emphasis that was mentioned in the founding documents of IEA. Ergonomics is a science of design. There are three important targets for ergonomics design activity: to improve safety, productivity and operator satisfaction. A systems approach is presented to define how these parameters interact and how they can be measured.

A previous study defined sitting comfort and discomfort as independent entities associated with different factors: discomfort is related to biomechanics and fatigue factors, and comfort to a sense of well-being and aesthetics. In this study a checklist for evaluation of chair comfort and discomfort was analysed in two field studies. In the first study two groups of subjects, ten secretaries and ten managers, evaluated two groups of ten chairs. Subjects assessed each chair three times during a workday using three different types of scales. The results of a factor analysis reconfirmed the factor structure of comfort and discomfort. Analysis of variance demonstrated that discomfort was related to fatigue accumulated during the workday, but it was not related to chair design. There was no significant Chair x Time period interaction, which implies that the rank order of preference among a set of chairs was established during the first assessment and did not change during the day. In a second field study 37 secretaries used three different formats of a Chair Evaluation Checklist with 14 items. The results of a factor analysis again confirmed the factor structure of comfort and discomfort. Analyses of variance demonstrated that subjects can evaluate comfort and discomfort simultaneously without any halo-effect. The results have methodological implications for measurement of comfort and discomfort. The findings for comfort, as defined, carry an important message that aesthetic design matters. This could provide a unifying focus for ergonomists and designers.

Trends in manufacturing suggest that manual assembly will change from routine assembly line work to small-batch, non-routine work involving teams and incorporating quality control. The changing role of manual assembly in manufacturing reinforces the long-standing need to understand the properties of work that are compatible with human capabilities and limitations. Although methods engineering and principles for economizing human motion provide helpful approaches to the characterization of physical work demands, they provide limited insight into the properties of manual assembly work affecting the information processing and learning so important in non-routine work. In this paper several alternative task description models are reviewed and applied to an assembly task to illustrate its cognitive properties. The authors focus on a symbolic, computational representation of assembly task knowledge to suggest that current trends towards small-batch manufacturing place demands on workers to extend their...

The ease of adjustability of ‘ergonomic chairs’ was investigated. Twenty-six chairs were classified with respect to control features. There were 24 different types of control arrangements. Twenty subjects participated in a series of three experiments. The first experiment investigated what types of control mechanisms could be identified by naive users who had received no training or instruction in the use of control devices. The chairs were classified into five broad categories, and one chair from each category was tested. Two control design features, control discernibility and control feedback, significantly improved users' understanding of the adjustability controls. In the second experiment controls on 20 chairs were evaluated. Subjects were first trained in the operation of the controls for each chair; and then they performed a chair adjustability task. Six control evaluation criteria were used: reachability, force, ease of operation, preference, time to adjust, and number of control activations. Cont...

The objective of this study was to determine if stature change and perceived comfort are significantly different for individuals with either healthy or herniated discs when seated in a conventional chair or a sit-stand chair. Sixteen subjects were studied (5 young/healthy, 6 old/healthy, 5 old/herniated). Subjects performed a search task on a computer screen during two 2 h sessions for two consecutive days, with a different chair each day. Changes in stature were measured with a stadiometer. General comfort and body parts discomfort rating scales were administered every 30 min. The main findings were: (1) for all subjects, the sit-stand chair produces less height loss than the conventional chair; and (2) for both chairs, subjects with herniated discs lost more height than subjects with healthy discs. A positive correlation was observed for height loss and age with the sit-stand chair. Subjects with herniated discs felt relatively more uncomfortable in the conventional chair and more comfortable in the sit-stand chair compared to subjects with healthy discs. Both old healthy and young healthy subjects felt more comfortable in the conventional chair in comparison to the sit-stand chair. But, old healthy subjects had a relatively greater perception of comfort in the conventional chair compared with the younger subjects.

Chair users have difficulties distinguishing between chairs of different ergonomics quality. Many ergonomics features that are supposed to relieve discomfort in sitting are indistinguishable because they cannot be perceived. This is due to poor proprioceptive feedback from ligaments, joints and the spine. The joints are relatively insensitive to small changes in angle, and the spine cannot sense differences in pressure due to different body postures. Aesthetics features on the other hand, and features related to comfort and relaxation, are easier to perceive and differentiate. A study of ergonomics chairs verified that users could distinguish between parameters that relate to aesthetics and comfort, but had difficulty in distinguishing between ergonomics features. In the end aesthetics may be more important than ergonomics--at least to the customer who will be guided more by aesthetics than longer-term ergonomic factors.