well as temporal and spatial components. Endsley's model of SA illustrates several variables that can influence the development and maintenance of SA, including individual, task, and environmental factors. In summary, the model consists of several key factors that describe the cognitive processes involved in SA: Perception, comprehension, and projection as three levels of SA, The role of goals and goal directed processing in directing attention and interpreting the significance of perceived information, The role of information salience in "grabbing" attention in a data-driven fashion, and the importance of alternating goal-driven and data-driven processing, The role of expectations (fed by the current model of the situation and by long-term memory stores) in directing attention and interpreting information, The heavy demands on limited working memory restricting SA for novices and for those in novel situations, but the tremendous advantages of mental models and pattern matching to prototypical schema that largely circumvent these limits, The use of mental models for providing a means for integrating different bits of information and comprehending its meaning (relevant to goals) and for allowing people to make useful projections of likely future events and states, Pattern matching to schema—prototypical states of the mental model—that provides rapid retrieval of comprehension and projection relevant to the recognized situation and in many cases single-step retrieval of appropriate actions for the situation. The model also points to a number of features of the task and environment that affect SA: The capability of the system and the user interface for conveying important information to the person in a way that is easy to integrate and process. Both high workload and stress can negatively affect SA. Information overload is a problem in many situations. Underload (vigilance conditions) can also negatively affect SA. The complexity of the systems and situations a person is in can negatively affect SA by making it difficult to form accurate mental models. Automation is a major factor reducing situation awareness in many environments (e.g. aviation, driving, power operations). See out of the loop performance problems. This is due to it creating situations where people are forced to become monitors which they are poor at (due to vigilance problems), often poor system transparency with needed information not provided, and an overall reduction in the level of cognitive engagement of people with automated systems Experience and training have a significant impact on people's ability to develop SA, due to its impact on