Direct Measurement of Situation Awareness: Validity and Use of Sagat

Introduction The Situation Awareness Global Assessment Technique (SAGAT), is a global tool developed to assess SA across all of its elements based on a comprehensive assessment of operator SA requirements (Endsley, 1987b; 1988b; 1990c). Using SAGAT, a simulation employing a system of interest is frozen at randomly selected times and operators are queried as to their perceptions of the situation at that time. The system displays are blanked and the simulation is suspended while subjects quickly answer questions about their current perceptions of the situation. As a global measure, SAGAT includes queries about all operator SA requirements, including Level 1 (perception of data), Level 2 (comprehension of meaning) and Level 3 (projection of the near future) components. This includes a consideration of system functioning and status as well as relevant features of the external environment. SAGAT queries allow for detailed information about subject SA to be collected on an element by element basis that can be evaluated against reality, thus providing an objective assessment of operator SA. This type of assessment is a direct measure of SA — it taps into the operator's perceptions rather than infers them from behaviors that may be influenced by many other factors besides SA. Furthermore it does not require subjects or observers to make judgments about situation knowledge on the basis of incomplete information, as subjective assessments do. By collecting samples of SA data in this manner, situation perceptions can be collected immediately (while fresh in the operators’ minds), reducing numerous problems incurred when collecting data on mental events after the fact, but not incurring intrusiveness problems associated with on-line questioning. Multiple “snapshots” of operators’ SA can be acquired in this way, providing an index of the quality of SA provided by a particular design. By including queries across the full spectrum of an operator’s SA requirements, this approach minimizes possible biasing of attention, as subjects cannot prepare for the queries in advance since they could be queried over almost every aspect of the situation to which they would normally attend. The method is not without some costs, however, as a detailed analysis of SA requirements is required in order to develop the battery of queries to be administered.