The first step in any decision model is understanding what is going on. This understanding is required by the decision maker to suggest tasks that can achieve a decision’s objectives. A decision maker’s assessment of a situation results in a product called Situation Awareness (SA) (Endsley, 1995b). The SA has emerged as a key cognitive construct of interest, formed from the terminology and challenges of the aviation field (Endsley et al., 2007). For an operator, SA is a mental representation of the world around him/her at any given point of time. In simple words, SA is about knowing and recognising what is going on around us (McIlvaine, 2007). It is required for moment-to-moment decision making and improved performance in complex systems (Endsley, 1988a). Nowadays, SA research has been extended to many other sectors like air traffic control, nuclear and petro chemical plant operation, military contexts, driving aviation, emergency response (Endsley, 2000; Stanton et al., 2005). 2.4.1 SA definition
SA has several definitions. For example, according to Smith and Hancock (1995) it is an externally directed consciousness that directs actions in a dynamic tasks environment. Whereas, according to Dominguez (1994) SA is also integration of information with previous knowledge to form a coherent mental picture and anticipating future events. In contrast, Taylor (1990) believed, SA is the knowledge, cognition, and anticipation of events, factors and variables affecting the safe, expedient and effective conduct of the mission. Sarter and Woods (1991) defined SA, based on the integration of knowledge resulting from recurrent situation assessments, but did not explain situation assessment. Other researchers have proposed alternative definitions of SA (Adams et al., 1995; Billings, 1995; Durso and Gronlund,1999; Stanton et al., 2005; Salmon, et al., 2008). The range of definitions arises in part from the complexity of different cognitive models and in part from alternative views that emphasise particular features of a situation. Also, some definitions are broad, whilst others try to present a structured interpretation of the assessment process.
Therefore, SA has a range of theoretical connections emanating from the work of Adams et al. (1995), Smith and Hancock (1995), and Endsley (1995). A universally accepted definition for SA has consequently yet to emerge (Stanton et al., 2005) but two theories of SA – the three level theory of Endsley (1995) and the perceptual cycle model proposed by Smith and Hancock (1995), have emerged as dominant (Stanton et al.,
49 2005). Endsley’s (1995) definition of SA has been applied in many domains (Wickens, 2008) and has become the most frequently used and extensively cited theory in the field (Albers, 1998; Klein, 2000; Son et al., 2007; Stanton et al., 2005). Moreover, Endsley has presented the best information processing approach compared with other models (Stanton et al., 2001).
2.4.2 Endsley’s three level model of SA
SA has been entailed as playing a conspicuous role in several emergency decision making strategies (Endsley, 1995a; Endsley, 1995b). According to Endsley (1995b), SA is a key facet of effective emergency decision making and operational performance. SA is mostly defined in operational terms. For a given operator, SA is defined in terms of goals and decision tasks for some specific job (Endsley, 2000). A formal and widely accepted definition of SA that has been found applicable across a wide variety of domains is therefore:
“The perception of the elements in the environment within a volume of time and space, the comprehension and the projection of their status in the near future” (Endsley, 1988a).
Perception is the first level of SA, it means understanding the importance of information about any situation. For example, in the context of a tsunami; earthquake magnitude, source location, depth and wave height and direction, if the earthquake source is in the water are critical attributes.
Comprehension is the second level of SA, it constitutes how people combine, interpret, store and retain information. Comprehension also includes integrating multiple pieces of information from SA Level 1 and determining their meaning and relevance to the operator’s goals. For example, combining the earthquake mangnitiude with the geograhical co-ordinates of an earthquake source, determines whether the earthquake is powerful enough and offshore to cause a tsunami or not. Moreover, processing the wave height information, if the source is offshore, it can be used to determine whether a tsunami has been generated or not.
Projection is the third and highest level of SA; it is the ability to forecast future situations from existing and previous situations. This ability allows timely decision making to counter any future risk. For a tsunami, forecasts would include predicted wave heights on arrival at the coasts, arrival time of waves, indication of areas under threat etc.
50 SA is critical to optimal decision making, but there are many other factors which play an important role. Klein’s work in the area of Recognition Primed Decision making provides strong evidence for the impact of situation recognition/classification and associated action selection (Klein, 1989; Klein, Calderwood & Clinton-Cirocco, 1986). The relation between SA and decision making is also discussed by Adams et al. (1995) and Smith and Hancock, (1994). SA informs decisions and SA is formed by feedback from decisions. Therefore, SA, decision-making and performance can be theoretically perceived as distinct stages that can affect each other and can be decoupled through other factors (Endsley, 2000).
Endsley (1995b), as shown in Figure 2.4 below, explained sources of SA information. Decision makers can directly observe the situation and they can use technology or systems e.g. internet, telephone, radios etc. or group members to collect subsets of available information. Decision makers perceive and interpret information that results in SA.
Figure 2.4 Information sources of SA (from Endsley, 1995b)
Although SA has a very significant impact on decision making, good SA does not guarantee optimal decisions (Son et al., 2007). Many other factors such as a change in the situation before the implementation of a decision, strategy, experience, training and personality, organizational and technical constraints may also affect the decision making process (Endsley & Garland, 2000). However, during emergencies, even experts can make incorrect decisions due to insufficient SA at different levels (Son et al., 2007).
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