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September 22, 2009

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An accident waiting to happen

Tim Marsh takes a wry look at whether some individuals are more prone to ‘human error’ than others and ponders whether determining susceptibility one way or the other is actually of any use to employers.

The inevitability of human error has been much discussed, and the fact that organisations need to work to minimise it and its impact heavily emphasised. It’s a rather controversial subject — because of the issues of blame and “scape-goating”, the importance of a “just” culture, and studies that show that it’s the environment not the person that is the root cause of the vast majority of problems, it is essential we focus on the individual only when all organisational factors have been systematically analysed.

While that cannot be denied, would you want your family to be in the hands of a pilot who was easily bored and distracted, low in conscientiousness, prone to day dreaming, hugely risk-tolerant, unintelligent, easily tired, and given to mood swings? Personally, I’d prefer them to be in the hands of someone conscientious, focused, risk-aware, emotionally stable, physically robust and clever, thank you very much! As a chap once said to me in a smoke shack; “Tim, this ‘just culture stuff is all well and good but there are a couple of muppets out there I wouldn’t trust to walk my dog!”

But I’d like to leave the minority of muppets to one side and concentrate on the typical worker, and how individual variations within a normal band can impact on safety. I’m talking about personality, intelligence (and its different types), and motivational drivers.

Each one of us is different
Firstly, some background theory. Individual differences can be categorised into three broad types:

  • Physical — size, etc;
  • Physiological — for example, health and fitness; and
  • Psychological — essentially intelligence, personality and motivation.

It’s fair to say that large, clumsy and badly coordinated individuals undertaking complicated tasks are more likely to have bumps. It’s also fair to say that unfit or poorly individuals will be more prone to tiredness, and that tired people make more mistakes and have more slips. We also know that badly-designed shift systems, or jobs with excessive physical or psychological strain can make people unnaturally tired and therefore accident-prone.

But there are many individual differences that little can be done about because they are innate to the individual in question. For example, different types of personality, motivation and intelligence can interact to cause stress, poor performance and safety issues. But this is where things get complex, as intelligence, motivation and personality are multi-faceted and interact in any number of ways.

As you can imagine, intelligent people usually make fewer mistakes than unintelligent ones, all else being equal. However, this isn’t always the case and studies show how intelligent people can be more likely to switch off when faced with mundane tasks. It’s said that peak performance is achieved between 40 and 70% emotional arousal. If we are working at less than that we are bored and therefore prone to distraction; if we are working at more than 70, we are stressed. Hence the old adage: “Brain surgeons make for crap taxi drivers.”

Regarding personality, there is any number of models based on everything from Freud’s Id and Ego through to the Simpson’s characters. (“Simpson” profiles can be surprisingly astute, as well as interesting — you really don’t want to be Homer!) Collated research, however, has focused on the “big five” factors: Extroversion; Anxiety; Conscientiousness; Open-Mindedness; and Agreeableness.

(Incidentally, my PhD used these factors to predict suicidal behaviour in army recruits. Unsurprisingly, I found that the army took anyone half sensible who would give basic training a go and then let that basic training sort out the ones who wanted to stay. The problem wasn’t just that it was those low in conscientiousness who made mistakes but also those who were anxious really worried about it. On top of this, the introverts hated barracks life, so anyone low in conscientiousness, as well as anxious and introverted tended to be having a horrible time. . .)

In a substantial piece of research collating the findings of dozens of studies and based on the “big five” factors, Clarke and Robertson1 found that personality factors such as conscientiousness and aggression did, indeed, correlate significantly with accident rates.

The actual figures are interesting, and illustrate the point. Though careless, over-confident, sloppy people have more accidents than careful, cautious people it’s just a statistically significant correlation — not a perfect correlation by any means. The real reason, of course, is that the environment is more important.

Peter Warr’s “Vitamin” model2 is, perhaps, the best description of what motivates people at work. His factors cover such basic things as money, prestige, and control, as well as more complex issues like role clarity, i.e. “I like to know what I need to do and hate vagueness” and “I like to understand how what I’m doing fits into the bigger picture”. You could call it the academic version of the phrase “different strokes for different folks”.

A related but simpler model of motivation (Vroom)3 explains why so many safety initiatives fail. It says that our motivation to do something follows this formula:

  1. We’re clear what we need to do; multiplied by
  2. We expect that doing it will lead to success; multiplied by
  3. We value the outcome.

As the three are multiplied a nought anywhere gives an overall score of nought. It’s a model well worth considering when we ask why a usually motivated supervisor hasn’t embraced a new safety initiative. Maybe because the training was vague and didn’t make clear what was required, or perhaps because they just don’t believe it will work.

A case in point
To illustrate how all these psychological factors can interact with a specific job and lead to error, let’s take the case of ‘Steve’ the incompetent manager. (The following is based on a real case involving a lack of containment at a chemical company).

Before describing what actually happened to Steve, however, here is a simplified list of some individual differences relating to task, personality and intelligence (as above) and my estimate of Steve’s rating on these on a 1 to 5 scale.

Spatial intelligence (working out how objects interact)     *****
Numerical Intelligence                                                      ***
Verbal Intelligence                                                            ***
Musical Intelligence                                                          *****

Natural ability/ personality/ preference for
Being in charge                       *
Working in a team                   ****
Task clarity                              *****
Job security                             *****
Power, influence and money    **
Strategic planning                    *

From this, it can be deduced that Steve was ideally suited to solving engineering problems as part of a team on a day-to-day basis: “Today’s engineering problem is this…” and off he goes. Afterwards, he goes home, spends some time with the kids, and plays his music. He was a fulfilled, highly competent and contented man. Then, because he was the best in the team, he was promoted and felt he couldn’t say no. (As you can see from the profile he’s a bit timid and doesn’t like to say no, because he hates confrontation.

Further, his family can use the money.) After a swift round of “rightsizing” he was promoted again. He was now in charge of process safety for a large and dangerous plant and was, of course, liaising with HR on a whole raft of training courses identified as relevant.

The task was difficult and vague and all about budgets, strategy and man-management, and, despite having the right technical qualifications, he was just not very good at it. Indeed, his emotional arousal was a long way north of 70 per cent and you won’t be surprised to learn that he got very stressed, very quickly, and started making mistakes — lots of them. A month or so later. the incident occurred. . .

So, is there such a thing (or word!) as ‘accident proneness’? I hope I’ve made the case that adding people to the workplace is a minefield (as if you didn’t know!) But is there a generally accident-prone personality? The short answer is that despite some recent controversy surrounding the subject, yes there is. Of course there is!
However, it has to be stressed that outside of hugely safety-critical tasks, like flying jets, it’s not really viable to use measures of these traits to influence the selection process. Further, focusing too much on the individual may well distract us from the bigger picture, which is that for the vast majority of tasks the environment is far more important than the person.

Most jobs are undertaken by average people, and so any job should be designed in the first place to minimise the likelihood or problems caused by individual variation occurring in the first place and maximise the likelihood of any errors being spotted, and quickly controlled when they do. Though complex psychological assessment is beyond the resources of most companies there are basic steps that can be taken to ensure a decent fit between task and person. For most situations, this will just involve task analysis and training.

People are different in a thousand different ways, and even differ day to day, and hour to hour. We just need to be aware of that when analysing incidents and reacting to issues. As ever, better than that, we should prepare for it pro-actively.


  1. Clarke, S and Robertson, I (2005): ‘A meta-analytic review of the big five personality factors and accident involvement in occupational and non-occupational settings’, Journal of Occupational and Organizational Psychology
  2. Warr, PB (1987): Psychology at work, Penguin
  3. Vroom, V (1966): ‘Organisation choice’, in Organisation Behaviour and Human Performance

Tim Marsh is managing director of Ryder-Marsh (Safety) Ltd, which specialises in cultural assessment and change, as well as behavioural safety.

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14 years ago

I use to work with a very incompitent manager the reason why i know is because i was he,s understudie and my way of thinking a plan of action for the day was on a bigger scale than his. he was getting the big money not me.< jelous i hear you cry> not at all i was more interested in the person who should of check his ability to do the job correctly. in meetings my surgestions to him on site was used in the meetings as his idears. and yes he did get 3 holidays a year with his… Read more »