Mica Endsley’s concept of situation awareness

Mica R. Endsley

Mica Endsley received a PhD in industrial and systems engineering. She served as Chief Scientist of the U.S. Air Force and is a prominent figure in cognitive engineering.

Endsley works on operator interfaces for various systems, including those for military, aviation, air traffic control, medicine, and power grid operations. Her work is focused on designing systems to support situation awareness and dynamic decision-making.

Endsley’s work

is significant for its emphasis on the practical application of cognitive research to real-world systems. Her work translates research findings into usable design principles and guidelines for engineers and human factors professionals. She has developed the Situation Awareness Global Assessment Technique (SAGAT), a widely used method for objectively measuring SA. Her research has impacted the design of systems across many domains, including aviation, air traffic control, medicine, military operations, and power grid operations.

For Endsley, the development of SA is a layered process that starts with the perception of essential environmental elements, progresses to comprehending the current situation, and ultimately projects future states.

Cognitive mechanisms, goals, and experience influence this process. Understanding these levels and mechanisms allows one to design systems and training programs that effectively support and enhance SA in various complex and dynamic domains.

Endsley includes

  • Three levels of situation awareness, which build on each other, which allows to track where awareness breaks down
  • Key cognitive mechanisms that influence the performance of SA
  • Challenges to SA
  • The influence of technical systems and consequences for the design of these systems.

Endsley has worked on designing technical systems and the intricacies of group situation awareness, but this post does not focus on these topics.

Situation Awareness model of Mica Endsley
Situation Awareness model of Mica Endsley

Use cases for the model

Endsley’s model provides a framework for designing systems and interfaces that support human situational awareness.

Aside of that, it is used in

  • Training and Education for various professions, including healthcare, first responders, and pilots
  • Safety and Risk Management. By understanding the factors that contribute to situational awareness failures, organizations can develop strategies to prevent accidents and errors
  • Teamwork and Collaboration: improvement of our understanding of how teams develop and maintain shared situational awareness.

Three Levels of SA

Endsley breaks down SA into three distinct levels. The idea is that a person goes through the three stages of recognizing the situation and can then act purposefully.

Level 1: Perception of the Elements in the Environment

This is the most basic level of SA and involves perceiving relevant environmental cues and information through our senses (sight, hearing, touch, etc.) and any available tools or displays.

The focus is on noticing and attending to important details, such as:

  • Objects and their characteristics
  • Events that are occurring
  • People and their actions
  • System status and indicators

Examples include a driver noticing a pedestrian crossing the street, a pilot observing the airspeed indicator, or a doctor monitoring a patient’s vital signs.

Level 2: Comprehension of the Current Situation

This level goes beyond simply perceiving individual elements and involves understanding their meaning and significance in the context of the current situation.

The focus moves to integrating the perceived information, recognizing patterns, and forming a mental picture of what is happening, such as

  • Understanding the relationships between different elements
  • Interpreting the meaning of events
  • Developing a coherent mental model of the situation

Example: A driver who understands that the pedestrian is crossing against the light and may pose a hazard, a pilot who understands that a sudden drop in airspeed could indicate a problem with the engine, or a doctor who recognizes that a patient’s changing vital signs could indicate a worsening condition.

Level 3: Projection of Future Status

Based on the current understanding, this is the highest level of SA and involves anticipating how the situation might evolve in the near future.

It’s about using knowledge and experience to predict potential states and outcomes.

This includes:

  • Forecasting the likely course of events
  • Anticipating potential problems or opportunities
  • Evaluating the consequences of different actions

Example: A driver anticipating that the pedestrian may continue crossing the street and adjusting their speed accordingly, a pilot anticipating that the engine problem may lead to a loss of altitude and preparing for an emergency landing, or a doctor anticipating that the patient’s condition may deteriorate and taking proactive steps to prevent further complications.

Cognitive Mechanisms

Endsley identifies several cognitive processes and mechanisms that contribute to SA. These include:

  • Perception and Attention: Individuals can only attend to a limited amount of information at a time, requiring them to selectively focus their attention on the most relevant elements. Factors such as the importance and rate of change of information influence attention allocation.
  • Working Memory: Working memory, which has limited capacity, plays a vital role in SA by temporarily storing and processing information from the environment.
  • Long-Term Memory (Mental Models, Schema, and Scripts): Long-term memory structures help overcome working memory limitations.

o Mental models are internal representations of systems that allow individuals to understand their behavior, explain observed states, and make predictions about future states. For example, a pilot has a mental model of how an aircraft responds to control inputs.

o Schema are mental frameworks that organize knowledge about specific situations, allowing for rapid classification and understanding of new information. They act as shortcuts, enabling individuals to quickly comprehend and make projections based on familiar patterns.

o Scripts are sequences of expected actions or events in a particular situation. For instance, a pilot has a script for takeoff procedures that outlines the steps involved.

  • Goals: Goals act as filters, directing attention to relevant information (top-down processing). They also provide context for comprehending and interpreting the perceived information.
  • Expectations: Expectations, derived from past experiences and knowledge, can influence the perception and interpretation of information.

The Demons to SA

The model identifies several challenges (the demons) that can hinder an individual’s ability to achieve and maintain good SA. These challenges stem from human information processing limitations and the complexities of individuals’ environments:

Attentional Tunneling: an individual focuses too narrowly on one aspect of a situation and misses other important information.

Can lead to: A limited and inaccurate understanding of the overall situation.

Requisite Memory Trap: the difficulty in remembering all the relevant information required to maintain SA.

Can lead to: As the demands on working memory increase, retaining and processing all the information critical for SA becomes challenging.

Workload: Workload, Anxiety, Fatigue, and Other Stressors (WAFOS),

Can lead to: It can impair cognitive functions and negatively impact SA. Stressors can reduce attentional capacity and information processing capabilities.

Data Overload: An excessive amount of information,

Can lead to: Individuals may struggle to process, prioritize, and make sense of the data, which can overwhelm their information processing capacity. This can lead to difficulty in identifying the most relevant information needed to make informed decisions.

Misplaced Salience: Less important information draws attention away from more critical aspects of the situation.

Can lead to: A distorted perception of the overall situation.

Complexity Creep: Systems become more complex.

Can lead to: Forming an accurate mental model of how the system works becomes increasingly difficult.

Errant Mental Models: Having an incorrect or incomplete mental model.

Can lead to: This can significantly impair SA. An inaccurate mental model makes it difficult to assimilate and process information correctly and also to form accurate projections. Mental models are crucial for directing problem-solving and interaction with a system.

Out-of-the-Loop Syndrome: Passively monitor automated systems, leading to a loss of SA and a diminished understanding of what the system is doing.

Can lead to: The out-of-the-loop problem may not simply be complacency but a fundamental difficulty in understanding what the system is doing when passively monitoring.

Poor Feedback: Systems do not provide adequate feedback.

Can lead to: This creates challenges for SA because key information is not effectively communicated to the operator. When feedback on system operation is eliminated or changed, monitoring what’s happening effectively becomes difficult.

Time constraints: Time is an important factor in SA.

Can lead to: Understanding how much time is available until an event is often a critical component of SA.

Shared SA: This can arise because team members might not be aware of what information needs to be shared or may assume that other team members have the same information.

Can lead to: Shared information might not be passed between team members. In addition, team members might falsely assume that others will arrive at the same assessments based on the same data.

To support SA, system designs must be built to mitigate these issues.

Designing for Situation Awareness

The collection of guidings including the “demons” leads to a number of design principles and guidelines aimed include:

  • Explicitly identify missing information: Systems should indicate when data is unavailable or unreliable to prevent users from making assumptions.
  • Support the rapid development of global SA of systems in an alarm state: Displays should provide a clear overview of the system’s status, particularly during emergencies.
  • Design systems to support the projection of future states: Displays should provide information and tools that help users anticipate future developments, such as trend graphs and predictive displays.
  • Highlight deviations from expected or desired states: Systems should use visual cues like color changes or alerts to draw attention to significant changes or anomalies.

Sources

Table Of Contents
  1. Mica R. Endsley
  2. Endsley's work
  3. Use cases for the model
  4. Three Levels of SA
  5. Cognitive Mechanisms
  6. The Demons to SA
  7. Designing for Situation Awareness

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