September 2, 2023 | Alex Paradies

Seven Deadly Human Performance Sins

What Are Common Reasons for Human Errors?

In over 35 years of teaching root cause analysis, we have seen thousands of ways for people to make mistakes. However, after a while, you see the same system weaknesses pop up again and again. It is sinful that companies haven’t picked up on these issues and stopped them. That’s why we call these issues the seven deadly human performance sins – because they increase human error, weaken your systems, and often result in deadly consequences.

The seven deadly human performance sins are:

  1. Employees don’t use procedures
  2. Fatigued employees
  3. Bad human-machine interface
  4. Bad verbal communication
  5. Supervision is too busy doing paperwork
  6. Corrective actions ineffective or not yet implemented
  7. Relying on people to catch their own mistakes

Sin #1: Employees Don’t Use Procedures

The 1st sin starts with the question:

What is a procedure?

We use the definition in the Root Cause Tree® Dictionary. The key to the definition is that procedures are written and used step by step to perform the work. The procedures aren’t policies and aren’t things you do from memory. Think of procedures as checklists … like a pre-flight checklist.


Memory is fallible. It is easy to lose track of where you are in your head. To skip steps, complete them in the wrong order, or misremember specific details. This can lead to disastrous results during high-consequence work.

It doesn’t matter how much experience you have. Pilots go through a step-by-step checklist every flight despite their years of experience. Why do they use the checklist when they could perform the task from memory after 1000s of flight hours? They use it because missing a critical detail before take-off could result in catastrophe. Procedures exist to prevent memory errors even in the most experienced worker.

Just for a minute, imagine that on your next flight the pilot made this announcement:

Welcome to our flight to Denver. I’ve completed 1,000 successful takeoffs
and landings so today, I’m going to skip the preflight checklist and just fly
this plane by the seat of my pants.

Would you ask to get off the flight?

So why do people not use procedures when it is proven to improve performance?

There are at least five reasons:

  1. The procedure is wrong
  2. The procedure is difficult to use
  3. The procedure is not required or easily available
  4. No one is enforcing the use of a procedure
  5. The work really shouldn’t require a procedure

To improve procedure use, you need to do four things:

  1. Make sure the procedure is correct for both sequence and efficiency.
  2. Make sure it is easy to use: formatting and availability.
  3. Explain to workers WHY procedures exist and WHY as a company, we use them.
  4. Show the importance of procedure use through actions like audits and management checks.
  5. Don’t require procedures for tasks that are within the worker’s skill and aren’t critical or hazardous.

Sin #2: Fatigued Employees

The 2nd human performance sin is the uninvestigated cause of many human performance problems. Have you ever considered how many times fatigue contributes to mistakes? Have you ever asked about fatigue when investigating an incident? If you never ask, you will never know.

If you do research on accidents, you will find that fatigue is a big deal. A research study on auto accidents took actual dash cam footage from cars and compared it to the police reports of accidents. It was rare that drivers admitted they were drowsy or fell asleep. Fatigue are falling asleep was not in the police report of the accident. But on video, they found accidents like this…

So, what causes fatigued employees? Here are just a few samples:

  • Poorly designed work schedules
  • Jobs where a person is required to maintain vigilance for long periods
  • Breaks are not based on environmental factors such as heat exhaustion or noise

To fight fatigue, consider these actions:

  1. Carefully consider industry fatigue prevention best practices when designing 24-hour rotating shifts.
  2. Allow for appropriate breaks.
  3. Employ fatigue monitoring when vigilance is required and can’t be mitigated.
  4. Frequently rotate people into and out of jobs that require extreme vigilance.
  5. Use automation to reduce boring monitoring.

Sin #3: Bad Human-Machine Interface

The 3rd human performance sin is poor human factors in human-machine interface design. One of the most famous examples of bad design is called the “Norman” door. What is a Norman door? A door where the signs or handles don’t match the operation of the door. For example, a door you have to push to open that has a pull handle.

Don Norman described these doors in his book “The Design of Everyday Things.” These doors cause frustration when people try to open them. Watch this video for examples…

So, if something as simple as a door can have a bad design, what about the computer interfaces and controls at your plant?

A good human-machine interface is easy (intuitive) to understand and operate. If a process has a good human factors design, it is easy to do right and hard to do wrong.

So, what leads to a bad human-machine interface? Here are some examples:

  • The layout, labels, displays, and controls are not aligned with good human factors principles.
  • People are forced to deal with similar but not identical designs, leading to confusion.
  • Processes or tools are plagued with bad ergonomics or require lifting excessive weight.

To fight bad Human-Machine Interface, start with these three suggestions:

  1. Use the Corrective Action Helper® Guide and Root Cause Tree® Dictionary to evaluate human engineering at your site.
  2. Create Critical Human Action Profiles (CHAP) for high-consequence work to evaluate what people need and what they have, to perform work.
  3. Use human factors trained experts to analyze critical or error-prone tasks or to evaluate new designs.

Sin #4: Bad Verbal Communication

The 4th human performance sin involves communication. When you tell someone something, is it written in stone? Do you expect them to remember it verbatim? Listening and remembering what is said requires attention and memory.

During incident investigations, people rarely say they “miscommunicated.” It is more likely that one party may claim to have said open valves “1,3, and then 2” and the other swears they were told to open valves “1, 2, and then 3”. Without evidence, whose recollection is correct?

For a laugh about communication, watch this…

So what leads to bad communication?

  • Poor communication hardware can lead to people miss hearing information.
  • There is no formal process for shift turnover/shift handoffs.
  • People are expected to remember long, jargon-heavy messages for extended periods of time despite the interference of daily duties.

To fight bad communication, start with these three ideas:

  1. Formalize your communication practices. This includes using 3-way communication protocols for critical verbal communication.
  2. Develop written shift turnover/shift handoff guidance based on industry best practices.
  3. Start recording (either video with audio or audio only) communications so problems can be accurately analyzed and improvements can be recommended.

Sin #5: Supervision is Too Busy Doing Paperwork


The 5th sin of human performance involves supervision. Would it shock you to learn that the job of a supervisor is less and less about supervision of work and more about handling business bureaucracy?

Is the role of a supervisor to make sure workers have what they need to do the job safely and effectively or is it to manage the ever-growing list of paperwork, report outs, documents, and systems?

The answer: “Yes!”

Supervisors are responsible for the preparation of work, selection of workers, and supervision during operations. However, how much of their time is spent in the field? 50%, 30%, 10%?

If a supervisor’s time is being consumed by an ever-increasing pile of paperwork, are we losing an experienced set of eyes to catch and prevent errors? Time management issues for supervision lead to shortcuts in preparation, pre-job briefing, team selection, and supervision of actual work. Will the supervisor be there when the worker has questions or will the supervisor be “too busy” to talk to the worker?

So what leads to supervision issues?

  • Supervision lacks resources to assist them in work planning, briefings, and team monitoring.
  • Explosion of “safety clutter” aka safety paperwork and other increasing bureaucratic systems taking time away from supervisor’s involvement with work in the field.
  • Crew staffing and scheduling decisions that are not based on human factors best practices.

To help struggling supervisors, start with these three best practices:

  1. Perform a time study to understand better where your supervisors spend their time. The goal is to look for things that can be taken off of their plates to free up time for additional time in the field.
  2. Look for resources to help supervisors diagnose issues with personnel. Fatigue monitoring equipment, substance abuse tests, and P.A.C.E plans (Primary, Alternate, Contingency, and Emergency) can help supervisors make faster decisions in the field.
  3. Create experienced team leader positions to help observe and support work when supervisors are unavailable.

Sin #6: Corrective Actions Ineffective or Not Yet Implemented

The 6th human performance sin is doing the same thing again and expecting different results. What was that the definition of again? . . . Oh, right insanity. Yet, we see time and time again. People use Re-corrective actions.

RE-write the procedure,
RE-inforce the rule.

If the training didn’t work last time, why would the same training work this time? If the procedure was written incorrectly or confusing the last time the procedure writer wrote it, why would he do better this time? Finally, if they didn’t follow the rule last time, how are you changing their incentive structure to make it more likely they will follow the rule this time?

So what leads to ineffective corrective actions?

  • People don’t understand the root causes they are trying to solve.
  • People are fixing symptoms and not addressing the true root causes.
  • People can’t see new ways to approach a problem more effectively.

To improve corrective actions, try these four ideas:

  1. Introduce advanced root cause analysis that meets the fundamental requires for good root cause analysis as a standard way your company analyzes issues.
  2. Start at the top of the Safeguard Hierarchy when writing corrective actions. Remove or reduce the hazard before implementing human performance corrective actions.
  3. Use the Corrective Action Helper® Guide to get ideas on solving problems effectively.
  4. Write SMARTER corrective actions to improve the corrective action’s effectiveness and ensure an individual is accountable for implementation.

One more idea. If corrective actions are not being implemented in a timely fashion, is management tracking corrective actions to completion and do they measure the corrective action’s effectiveness once they are implemented?

Sin #7: Relying on People to Catch Their Own Mistakes

The final human performance sin is asking people to do jobs that are contrary to human performance principles and then catch their own mistakes. We’ve tried to find human factors research that shows that humans can be trained to deny human nature and become robotic, error-proof error checkers that constantly check and recheck the accuracy of their actions and the actions of those around them, but … we can’t find any such research.

Yet, there are many human performance experts who teach techniques like STAR, Questioning Attitude, or Error Traps and Precursors for workers to employ to catch their own mistake.

I sometimes call these techniques snake oil because they seem like they should work, but there is no human factors research to prove their effectiveness. Even worse, people have been proven to be poor at self-checking for errors and then preventing the mistakes.

To get high reliability, you have to do something different.

So what leads to the last sin?

So, what can someone who wants to avoid snake oil do? Attend the Stopping Human Error Course.

To see the next scheduled public Stopping Human Error Course, CLICK HERE.

Why Should You Attend the Stopping Human Error Course?

Why should you attend the Stopping Human Error Course? Ask these questions:

  • Do you want to stop the seven deadly human performance sins?
  • Do you want to achieve excellent human performance?
  • Would you like to understand the methods you can apply to effectively stop major accidents and incidents by “stopping” human error?
  • Do you need to understand the most effective human performance improvement techniques/tools and which ones are counterproductive (yes, some techniques don’t work and may cause people to hide errors)?

If any of the above questions received a “Yes!” answer, you should attend the Stopping Human Error Course.

The instructors will help you understand:

  • The causes of human error
  • Human factors design best practices
  • Methods to find error-likely situations
  • CHAP (Critical Human Action Profile)
  • Human performance improvement technology (Hu – Human Performance Tools)
  • How to design your human performance improvement program for maximum effectiveness

You will leave this course with a clear understanding of methods to improve human performance and a plan to apply those methods at your company to achieve great gains in safety, quality, or operational and maintenance performance (all of which depend on human performance).

Stopping Human Error

Participants will also receive the book, Stopping Human Error, a $99.95 value, as part of the course materials.

See the schedule for upcoming public Stopping Human Error courses HERE. Or contact us to schedule a course at your site.

Alex Paradies
Human Performance
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