Rockin’ New Human Performance Investigation Tool

Most problems and accidents involve human activity at some point or other. Often, this activity is right at the point of occurrence, and people at the sharp end are usually operating under difficult or confusing circumstances. They make decisions and take actions that, in hindsight, prove to be "wrong" in some way. Then, after something "bad" happens, we perform an investigation and find these "human errors"... and all too often, we stop there without really considering all the factors that shaped the undesired outcome. This article discusses a new tool that has been developed (by me) to help investigators find these factors so they can be used as starting points for root cause analysis.

I developed this tool because I was not satisfied with the existing tools that I have seen. Invariably, these tools were too simplistic, too complicated, or too proprietary. I also wanted something that would be easy for me to remember and reproduce, so that I wouldn't have to carry around some kind of reference document. Finally, I wanted a comprehensive tool that included a wide variety of factors that I have found (through experience) to be important. It should be noted, however, that this tool should not be treated as a comprehensive model for human performance! It is only a tool to help an investigator remember important factors to be considered; it cannot be used to judge the importance of any specific factors. Nevertheless, I have found this tool to be quite useful in my own work, especially during the investigation phase of root cause analysis.

The tool is basically a phrase consisting of first-letter mnemonics that can be used to recall a set of four categories, each containing five separate items, for a total of twenty individual factors. The basic mnemonic is "AC/DC - CHEST PAINS, FRIES & STEAK." Yes, this seems silly. Even sillier is the visualization I use to trigger recall of the entire mnemonic - basically, I picture an overweight, balding man with a pony-tail (kind of like Comic Book Guy from the Simpsons), wearing a too-tight, black AC/DC concert shirt, and clutching his chest with one hand while his fast-food bag (containing a super-sized order of french fries and a steak sandwich) falls from his other hand to the floor. (My apologies to any AC/DC fans reading this - I hope this doesn't describe you.)

So, that's the entire mnemonic, including a cheesy visualization for enhanced recall. The first part - "AC/DC" - provides the four categories that define the structure for the rest of the phrase. It is expanded thusly:

  • Activity - Factors describing the activity that was underway when the bad thing happened.
  • Culture - Factors describing the cultural influences on performance of the activity.
  • Direction - Factors describing the directions associated with the activity.
  • Competence - Factors describing the competence of an individual for performing the activity.

The remaining words in the phrase are associated with each of the above categories, in the order provided, e.g., CHEST is associated with Activity, PAINS with Culture, and so on. The expansions and explanations for each of these words are provided below.


  • Complexity - How complex or complicated was the task? What was the difficulty level?
  • Hazards - What hazards were involved in the task? Were the hazards identified prior to starting the activity? What defenses were employed?
  • Environment - What were the features of the work environment that might have impacted task performance? What kinds of difficulties did these features cause?
  • Sequence - Was a specific sequence of steps required? What was the sequence? Was the sequence followed? What were the consequences of not following the required sequence?
  • Tools - Were any tools required to perform the activity? Were they suitable for the task? Were they in good condition? Were they used properly?


  • Priorities - What were the individual's priorities in performing the activity? Were did they come from? What impact did they have?
  • Attitudes - What were the attitudes possessed by the individual that might have affected their decisions or actions? What impact did they have?
  • Incentives - What incentives did the individual have ? Where did they come from? What impact did they have? Were they implicit or explicit?
  • Norms - What were the accepted norms of behaviour for the organization? Were the individual's actions consistent with these norms?
  • Stresses - What organizational and individual stresses were relevant to the performance of the activity? What impact did they have?


  • Formality - Were the directions conveyed formally or informally? Verbal or written? Paper or email? Were formal communications protocols adhered to?
  • Requirements - What requirements, or "musts", were associated with the activity? How were they conveyed? Were they understood? Were they met?
  • Instructions - What instructions were provided to direct performance of the activity? How were they conveyed? Were they accurate? Were they understood? Were they executed? What was missing?
  • Expectations - What were the expectations of the performer regarding the activity? What other expectations were relevant? How were they communicated? Were they reasonable? What impact did they have?
  • Supervision - What did the supervisor say (or not) prior to the start of the activity? Was the supervisor involved in the execution of the activity? What kind of oversight did the supervisor provide during performance of the activity?


  • Skills - What specific skills were required to perform the activity correctly? What skills did the performer possess? Were there any mismatches?
  • Training - What training had the performer been provided, either specific to this activity, or in general? What was covered by the training, and when was it provided? Did the performer possess all the required training qualifications?
  • Experience - Has the performer completed this activity before? How frequently? How recently? What level of general experience did the performer possess?
  • Aptitude - What level of aptitude did the performer have for this specific activity? Did the performer consider this to be an easy or a difficult activity? Was the level of aptitude sufficient for the difficulty level?
  • Knowledge - What did the performer know about the details of the activity, including it's importance? Was the performer's level of understanding sufficient? What factors, not known by the performer, were important to how the event or problem evolved?

That's the entire tool. I find it useful because I can use it to rapidly generate the list of 20 factors anytime I need to, without reference to any kind of book, report, or user aid. I've used it many times to structure interviews, and/or guide my other evidence-collection efforts. I can't claim that all important factors, for all types of events, are included - but I do believe that the factors included in the tool are among the most important for investigating human performance events and problems. I've reviewed the breadth of coverage by comparing the complete set of factors to a number of well-established tools (such as MORT and the Savannah River Root Cause Map), and I don't believe there are any significant gaps.

I hereby release this tool for free usage by anyone that finds it to be useful. You may even reproduce this tool in published works. However, I require that you do not claim it as your own in any published work, and that you reference this web page as the original source. Finally, I request that you leave a comment on this web page if you use the tool - let me know how it worked for you, or if you have suggestions to improve it.

by Bill Wilson
Loading Quotes...

Site Map
Bill Wilson © 2004-2020

Last updated: November 18, 2014 at 12:37 pm

You may also like...

1 Response

  1. Hi Bill, I recently showed your questioning model to some local safety professionals at a regional conference as part of my presentation on systems thinking in accident investigation. They found it a very useful tool for expanding the 5 Why process. Several have told me that they are now pouring through your blog in search of more tips. Thanks for putting this material out there. I teach incident analysis at Central Washington University and I’m going to add this model as an example of expanding upon the 5 why’s to try to get the students thinking a little less linearly. I still get lots of 5 why exercises that simply point to human error as the root cause.

Leave a Reply

Your email address will not be published. Required fields are marked *