HUMAN DECISION MODEL

This model is designed to help investigators formulate questions when they inquire into what people did, and why they did it. The Model deals with interactions between people and other people or objects during systems operations. It helps investigators discover sensory, communication, diagnostic, attitudinal, decision making, training, design, procedural, supervisory and many other problems related to "human factors" in a way that defines specific problems, needs and actions, rather than ambiguous or abstract categories of "factors" or root causes or unsafe actions or unsafe conditions.

To apply this Model during investigations or interviews, the following is offered:

First, identify people who appear to have acted and affected the outcome of the incident process. Then begin to look for a change in the activity that would have created a need for action by that person to keep the activity progressing toward its intended outcome.
When you identify that change, determine if it emitted some kind on signal that the person could have noticed. If it didn't you explore why it didn't and what effect that had on the outcome.
If it did emit a signal, explore whether the person saw, heard, felt or otherwise "observed" the signal. If not, explore why not, and what effect that had on the outcome.
If the person observed the signal, was the signal diagnosed correctly, in the sense that the person was able predict the consequence of the change from the signal and their knowledge of the system and its operation. If not, explore why not, and its effects.
If the predicted consequences of the change were correctly identified, did the person recognize a need to do something (intervene) to counter those consequences? If not, explore why not, and its effects.
If so, did the person identify the choices for action that were available for successful intervention? Was this a new situation were the action had to be invented, or was this something that prior training anticipated and provided the responses to implement? In other words, was the person confronted by an adaptive or habituated response? (Here, you start to get into the person's decision making process, and potential personal judgment issues, so explore this area with empathy toward the witness, particularly for adaptive responses.) Other paths might lead to training, hazard analysis, prior deviations, policy, etc.
If any response actions were identified, did the person choose the "best" or an effective response to implement? If a successful response was not chosen, explore why it wasn't. Was it an interpretation or diagnostic problem, time constraint, training problem, risk decision making skill problem, distraction, etc.?
If a successful response was chosen, did the person successfully implement the desired action? If not, explore why not. Was it a skill problem, timing problem, support problem, tools problem, etc.?
If a suitable response was implemented, the system adapted to the change without an accidental loss or harm. If the response did not achieve a no-accident outcome, explore why it didn't. Often this leads you to discovery of invalid system design assumptions or other design problems. Recognize what kept incident from becoming major loss.

After working with this model, you will be in a much better position to describe and explain what happened when a so-called "human error" or "failure" is alleged. You will also be in a better position to identify concrete actions to improve future performance of that system.