Human Factors in Error Reduction

Human Factors in Error Reduction

by Barry Henson. CEO, Desertfire Online

“Kitty Genovese.” The name tugs at the strings of your memory, then comes the terrible recollection; Kitty Genovese was the young woman infamously stabbed to death on a New York street, while dozens of people listened or watched — and not one of them went to her assistance or even called the police.

So what does Kitty Genovese’s murder have to do with lean manufacturing and manufacturing excellence?

The same psychological principles that prevented those bystanders from coming to her aid are affecting the workers at your facility, preventing them from: enforcing safety rules, conducting effective QA checks, reporting production and maintenance problems and working together effectively. The better you and your management team understand these psychological principles, the better equipped you’ll be to reduce errors and improve manufacturing performance.

Let’s start this journey by asking a fundamental question:

How could a group of normal, good-hearted people, witness something so wrong and not take any action?

The answers are found in the psychological principles of ‘social proof’ and ‘dilution of responsibility’. A firm understanding these principles is critical to effectively shaping human behavior.

Social proof is the psychological principle that states that ‘people generally look to the behavior of others to determine appropriate behavior’. In other words, as a cooperative species that works together to survive, we have a natural tendency to follow the behavior of those around us. This principle holds especially true in situations that are threatening, out of the ordinary or where we are confronted with a large number of choices.

Marketing professionals have long understood the power of social proof. When faced with a buying decision, consumers minimize the risk of making the wrong choice by buying the most popular brand. Consequently, marketeers spend a great deal of money and effort trying to establish their product as the ‘best seller’ in an effort to make us feel that “it must be good because everyone else thinks it is”. This is the principle of social proof.

Unfortunately, social proof doesn’t necessarily lead us to make right choices. Indeed, looking to others — who may be just as uncertain how to react as you are — can have costly, even tragic consequences. This was the case with Kitty Genovese. The fact that none of her neighbors visibly went to her aid led to them individually concluding that not going to her aid was the correct course of action.

While social proof explains why none of Kitty Genovese’s neighbors went to her aid, it doesn’t explain why no one called the police. To understand this we need to look at the principle of dilution of responsibility.

Dilution of responsibility is a psychological principle that states that ‘the presence of multiple people results in each individual feeling less responsible’. In other words, as the sole witness to an event you realize that if you don’t act, no one will — consequently you feel a strong sense of responsibility. When multiple people are present, that sense of responsibility is diluted as each person assumes that someone else will act. Dilution of responsibility is why you have a better chance of surviving a heart attack when only one or two people are present, than you do if you to have a heart attack on a busy downtown street.

In Kitty Genovese’s case, because so many people witnessed the attack, responsibility for calling the police was diluted. Each person in turn assumed that someone else would call the police. Sadly, police investigating the murder determined that had even one of her neighbors intervened or called the police at the beginning of the attack, Kitty would be alive today.

What types of errors and problems in the workplace are caused by social proof and dilution of responsibility?

Case Study: GMP at Pharmaceutical Plant

During a recent visit to a pharmaceutical company, a maintenance worker entered a packaging room and — while exposed product was being packed — he started drilling into the drywall to install a new electrical switch. This was a clear violation of good manufacturing practice and the dust released by the drilling created an obvious contamination risk. The packaging room operators present at the time were experienced employees, trained in good manufacturing practice, with several years of service.

So what happened?

The operators observed the maintenance worker and looked around at each other. No one moved from their workstation. After a little while, the operators shrugged and got on with their job. No one approached the maintenance worker. Later that shift, the incident was reported and the entire batch placed on hold. Over $180,000 of product was compromised.

Why did these experienced employees take no action in the face of something that was obviously wrong?

In follow-up interviews operators were asked why they didn’t act. Several people commented to the effect that:

“While I thought what he was doing was wrong, the fact that he was doing it made me think ‘He must know something I don’t’ ”.

“I figured he had to have someone’s approval to do it”.

Most people also said that they were afraid that stopping the worker might offend him and damage their relationship. Lastly, the fact that no one was willing to intervene, confirmed in their minds that this was the correct course of action. Dilution of responsibility and social proof had combined to produce a costly error.

Other examples of problems caused by dilution of responsibility and social proof include:

Absenteeism – “If I’m not here, someone else will take care of it”. (dilution of responsibility). “Everyone else does it” (social proof). The larger the organization, the more dilution.

Errors in reviews by multiple people – This is particularly the case where a document is filled in by one person, checked by another, then released by another and each level checks and corrects errors from the previous level. “If I make a mistake someone else will pick it up” (dilution of responsibility). The more people involved in the checking process, the greater the dilution.

Turning a blind eye to safety – similar to the example in our case study:

So, how do you address these issues?


Initially, you will need to “combat” social proof and dilution of responsibility until you change the group norms. This means creating high personal accountability and enforcing it. For example: in the case of absenteeism, there has to be personal contact with the absent individual, preferably during the period of their absence, to leave no doubt that their absence was noticed and that their presence was missed by their team mates.

In the case of multiple people checking documentation, the process of checking should include a feedback and recording loop which records which errors were made by the previous individual and feedback given as soon as possible back to that individual. Merely correcting the errors diminishes the person’s responsibility, but if the person knows that their errors will be detected, recorded and communicated, they will feel personally responsible and accountable.

Who are Desertfire Online?

We are a group of engineers and psychologists dedicated to improving manufacturing performance by improving the transfer of knowledge in the workplace.  Desertfire Online products are used by Fortune 500 and Forbes 2000 companies are available in up to 24 languages.

Contact us for more information on how to reduce human error in your workplace.

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