Skip to content

IDHEAS-ECA

IDHEAS-ECA (Integrated Human Event Analysis System for Event and Condition Assessment) is an HRA method documented in NUREG-2199. It analyses human performance through five macrocognitive functions, providing a more detailed cognitive model than spar-h's PSF-based approach.

Five Macrocognitive Functions

IDHEAS-ECA decomposes human performance into five cognitive functions:

  1. Detection: Perceiving that a situation requires attention (noticing alarms, recognising parameter deviations)
  2. Understanding: Comprehending what the detected information means (diagnosing the plant state)
  3. Decision-making: Selecting the appropriate response from available options
  4. Action execution: Physically carrying out the chosen response correctly
  5. Teamwork: Coordinating with other crew members, communicating, and maintaining shared awareness

Natural Human-AI Extension

The teamwork function already models interaction between crew members, making IDHEAS-ECA the most natural framework for extending to human-AI interaction. The AI advisory system can be modelled as a team member that the operator interacts with during each macrocognitive function.

AI introduces new cognitive failure modes (CFMs) mapped to specific macrocognitive functions:

automation-bias → Decision-making: Operator follows incorrect AI recommendation without independent evaluation. The AI recommendation biases the decision-making process.

Alert fatigue → Detection: Repeated low-value AI outputs cause the operator to stop attending to AI advisory channels. A genuine AI alert is missed because the operator has learned to ignore the channel.

Mode confusion → Understanding: Operator misunderstands the AI system's current operating mode, context, or confidence level. The operator interprets AI output based on incorrect assumptions about what the AI "knows."

Reconciliation failure → Teamwork: Operator fails to resolve discrepancy between their own assessment and the AI advisory. Rather than investigating the disagreement, they either blindly accept or dismiss the AI input.

CFM/PIF Distinction

IDHEAS-ECA maintains a clearer distinction between cognitive failure modes (what goes wrong cognitively) and performance influencing factors (what conditions make the failure more likely) than spar-h. This cleaner separation makes it easier to systematically map AI influences to the correct level of the analysis — AI system reliability is a PIF that affects the probability of automation bias (a CFM) in the decision-making function.