The PCM is presented in Figure 3.1; as previously described, this is an information processing model based on the idea of a reciprocal, cyclical, relationship between an operator and their environment. This ecological approach suggests information processing is cyclical rather than linear, and active rather than passive. The PCM provides a model of individual cognition based on schemata which are personal mental representations, but it recognises that cognition is extended beyond

the individual because perceptions, decisions and actions are grounded within the context of the environment in which they occurred. The aviation industry has previously been criticised for studying judgement and decision-making out of the context in which it occurred, assuming that errors are the result of either technological or human failure, rather than the joint human-technology system (Maurino, 2000; Hobbs and Williamson, 2002). The recognition of both the individual and the environment has resulted in the model’s popularity and endurance in Ergonomics research. The PCM explains the way in which the world constrains behaviour as well as how cognition constrains our perception of the world. The model encompasses both top-down and bottom-up information processing and explains how everyday behaviour is formed through a mixture of both approaches. As such, the model has been readily applied in the Ergonomics discipline. For example, Smith and Hancock (1995, p. 141) used the PCM as the foundation for their perspective of SA, arguing:

Stanton et al. (2001, 2009a,b) argued that the interactive nature of the PCM is good at explaining the dynamic aspects of SA and the collective behaviour of systems as a whole, as opposed to individuals. As such, Stanton and colleagues used the PCM as one of their underpinning concepts in their theory of DSA (Stanton et al., 2006; Salmon et  al., 2009a). This approach argues that awareness is distributed across human and technological agents involved in collaborative activity (Salmon et  al., 2008a).