Human Failure Series: Slips and Lapses

September 26, 2017




Following a recent workshop we held for accident investigators we were surprised the number of questions and interest surrounding Human Failure.


Human Failure is an inevitable cause of many incidents and these investigators were struggling to dig deeper into the issues behind the errors.  It occurred to us that others may have similar questions and that others, including Managers and Business owners, would benefit from a better understanding of the principles behind Human Failure.


Over the course of 3 blogs we are going to cover Human Failure in a way that you can take the knowledge and apply it to your own place of work.


This first blog will cover Human Errors and, specifically, Skill-Based Errors.




Types of Human Failure


There are 2 types of human failure.

  • Human Error, and;

  • Violations

The former, Human Error, refers to actions that were not intended.  Human Error’s can also be broken down into two types.  Skill-Based Errors and Mistakes. This first blog is going to tackle Skill-Based Errors.


Skill-Based Mistakes

Skill-Based Mistakes are often referred to as ‘Slips’ and ‘Lapses’.  They apply to tasks that can be performed with little concentration.  They will be familiar tasks such as driving, walking et.  These types of tasks are particularly susceptible to slips and lapses.


Slips are when people do something that they’re not supposed to.  For example:

  • Braking your car too late, or too early.

  • Not putting your PPE on before you start a task.

  • Accidentally neglecting to carry out a step in a process (e.g. not checking your mirror before reversing)

  • Performing a task with too much force, or too little (e.g. hitting a nail too hard and bending it).

  • Carrying out a task in the wrong direction (e.g. moving a lever up instead of down)

  • Performing the correct task but on the wrong item.

  • Adversely, carrying out the wrong task but on the correct item.


Lapses are when people omit to do an action or lose track of where they were in a process. For example:

  • Forgetting to tighten a nut during assembly.

  • Taking your hearing protection off to hear what a colleagues is saying.

  • Being interrupted and forgetting to perform an action.

  • Performing a task out of sequence (e.g. started painting before taping the edges).

I think all of us can relate to slips and lapses (some more than others). Whilst on the surface they are Human Failures there are specific ways to address these types of Human Failure to reduce their occurrence.


Identify Tasks that are at Risk to Slips and Lapses

Review your tasks and identify those that require little thought to perform them.  This includes tasks that can be easily mixed up or that are difficult and not logical.  Tasks that have lots of fine details to complete are also susceptible as are tasks that are prone to interruptions and distractions.


How to decrease the likelihood of slips and lapses

  • Firstly, acknowledge with your own management and employees that slips and lapses do happened.  This is an unescapable fact. Acknowledging this allows you to move past the individual and start to look at the supporting actions and procedures.

  • Use checklists and other written instructions.  This is particularly helpful where a set sequence must be followed or tasks are complicated with many facets.

  • Write your procedures to include setting up of tasks and shutting down. This gets people thinking about the task in its entirely and include any quality control checks or similar.

  • Consider putting additional checks into place.  These could be engineering controls such as gauges, alarms and monitors.  Or, it could be visual checks carried out by others.

  • Reduce the likelihood and occurrences of distractions.  E.g. if alarms, doorbells or phones keep going off that interrupt staff then try to handle these in a way that reduces or eliminates the disruption.



Many daily tasks you carry out at home and at work are susceptible to Skill-Based Errors.  Make sure employees are aware that they are susceptible to slips and lapses and remember that additional training does not reduce the likelihood of slips and lapses.  Even highly trained individuals are susceptible to slips and lapses.


To do

Carry out a review of your tasks based on the risk factors described above.  Identify which of the above bullet points can help to reduce the likelihood of slips or lapses occurring. 


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