The growing emphasis on the importance of organisational and management factors in occupational safety, discussed in the previous chapter, has led to the relative neglect of psychological factors related to the individual. This chapter presents an overview of these variables, including human factors and individual differences, and how they are related to safety at both an individual and an organisational level.
Much of the earliest research examining the causation of accidents focused on human factors, with a particular emphasis on identifying defects of cognition, attention, perception or intelligence related to accidents. Researchers discovered that there is unequal liability to accident involvement (Newbold 1927; Farmer and Chambers 1926) and concluded that this variation is related to individual differences. Significant differences in intelligence, skills and personality have been found between accident and non-accident groups of pilots, for example, supporting the human factors explanation (Biesheuvel and White 1949).
Human factors have been identified as relating to driving ability and road traffic accidents (e.g. Porter 1988; Arthur et al. 1991; Evans 1991; McKenna et al. 1986). Brown (1990) suggests that attentional errors account for 40 per cent of road accidents, perceptual errors for a further 25 per cent and judgemental errors account for another 10-15 per cent of accidents.
There is limited evidence for a relationship with information-processing or cognitive ability and accidents. Arthur et al. (1991) conducted a meta-analytic review of information-processing and