Author: Jules Blackham, Jason M Kendall, Roland Watura / Editor: Jason B Lee / Reviewer: Rebecca Ford, Peter Lynas / Codes: RP3, SLO11, SLO2, SLO8 / Published: 04/02/2022

What are Human Factors?

This e-learning session will explain what is meant by the term Human Factors and describe how Human Factors affect Patient Safety.

A definition of Human Factors:

“These skills can be defined as behaviours not directly related to the use of medical expertise, drugs or equipment. They encompass both interpersonal skills e.g. communication, team working, leadership, and cognitive skills e.g. situation awareness, decision making. Such skills are not new, good doctors have always demonstrated these competencies. However, training can improve these skills.” [1]

Understanding Clinical Error

Clinical error can be broadly defined as any error in conduct or judgement in the clinical environment, irrespective of the whether or not the error produces or is the main cause of an adverse event. Experts estimate that at least 50% of clinical error is avoidable.

In 2007:

  • 8.7% of admissions had at least one adverse event
  • 15% of adverse events resulted in impairment or disability which lasted >6 months
  • 10% contributed to patient death
  • Increased mean length of stay of 8 days

Around 900,000 patients (10%) were affected by an adverse event that put their safety at risk. At a cost of around £2 billion in increased length of hospital stay. Whilst these are crude figures, they gives some indication of the frequency of the problem at a local level [2].

How and why do clinical errors occur?

Clinical errors are caused by human error and equipment faults – with human error being responsible for about 60 – 70% of clinical errors.

We are fallible and we make mistakes, in healthcare the consequences of these mistakes can be catastrophic.

Human error can occur because of limits to performance in:

  • Wellbeing
  • Cognitive error
  • Over/ underestimate abilities
  • Situation analysis

Other factors that can cause error:

  • Environment
  • Workload
  • Organisational culture

Improving Patient Safety

A strong safety culture is essential for improving patient safety and is commonly defined as:

“A collection of characteristics and attitudes in an organisation promoted by its leaders and internalised by its members, that make safety an overriding priority” [3]

A more succinct definition is: ‘what the organisation does when nobody is watching’. All organisations have a safety culture; that partially determines how the individuals within that organisation behave because the values of the organisation shape the actions of the individual.

Elaine Bromiley Case

Elaine Bromiley was admitted to hospital for routine sinus surgery. During the anaesthetic Elaine experienced breathing difficulties, several unsuccessful attempts were made to secure Elaine’s airway.’ Elaine suffered brain damage and deteriorated over the next 13 days, never regaining consciousness.

Read this extract from the summary of the case [4]:

“The management of the ‘can’t intubate, can’t ventilate’ situation did not follow the accepted Difficult Airway Society guidelines.

In particular too much time was taken in trying to intubate the trachea rather than concentrating on ensuring adequate oxygenation by other means such as direct access to the trachea.

Whilst theatre staff ensured that all necessary equipment was available, the clinicians appeared to become oblivious to the passing of time and thus lost opportunities to limit the extent of damage caused by the prolonged period of hypoxia.

Given the skill mix of the clinicians, it would have been very easy to perform a surgical procedure to gain access to the trachea. Theatre staff, when interviewed, all seemed surprised that such was not performed.”

This report has been made available by the Bromiley family for the purpose of learning. The full report can be found here:  Elaine Bromiley case report

Many elements of the error chain have been directly identified in this case as Human Factors errors which are easily preventable.

Click here to view the video re-enactment of the real life clinical error.

Swiss Cheese Model

The Swiss cheese model [5]

Reason saw errors like a block of Swiss cheese. There are many holes in our defences but very rarely do the holes line up to create a clear passage through the cheese. In the same way he describes that the contributing factors to error exist at all times within healthcare

Some errors (the holes in the cheese) represent latent conditions; these are things that can go wrong in a system due to the way it is designed or managed. Examples are understaffing or inadequate equipment.

Other errors are due to active failures; unsafe acts committed by people who are in direct contact with the patient or system.

Latent failures can be identifies and remedied by near miss reporting and risk management. Most incidents involve a combination of active and latent failures.

The Shell Model

This model considers the role of different factors on the delivery of safe patient care [6].

S = Software

Consists of all non-physical resources, required for the running of the organisation, e.g. organisational policies and rules, procedures and manuals.

H = Hardware

Equipment, tools, workspace, buildings and other physical resources without human elements in healthcare.

E = Environment

Includes not only the factors affecting the site where people work such as climate, temperature, vibration and noise, but also socio-political and economic factors.

L = Liveware (group) The term liveware refers to the relationships between colleagues.

L = Liveware (individual) What effect are the other elements having on individual factors like teamwork, communication, leadership and culture.

The Bow Tie Model

An approach to error management is to use a bow tie model [7]. Bow ties are based around a top event; the event or situation at which no adverse consequences have yet occurred, but where control over the process has been lost. It focuses both on the events leading up to the top event (and barriers to minimise this risk) and on the actions which should be taken after the top event to minimise the consequences.

Key Points

Here are the key points from this section:

  1. Human error can simply be described as an error made by a human.
  2. Two-thirds of all clinical errors involve human error.
  3. It is estimated that 50% of clinical errors are preventable.
  4. Errors can be latent which means they occur because of the way a system is designed or managed.
  5. Active errors occur because of unsafe acts committed by people in direct contact with the patient.


Cognition is the process by which our brains gain information and understanding.

In this section we will explore the different mechanisms the brain uses to process thoughts, senses and experiences.

Thought processes can be either conscious or automatic (unconscious). These are characterised by:

Conscious processes
  • slow and effortful
  • use working memory
  • 5-9 facts
  • flexible
  • the last resort method
Automatic processes
  • fast and effortless
  • subconscious
  • highly practiced
  • inflexible

Attention Mechanisms

Attention mechanisms are the processes that prompt us to pay attention to particular stimuli.

Divided Attention

Q. Are you good at multitasking?

The brain cannot simultaneously focus on different tasks, so multitasking is actually a process of continually refocusing or toggling between different sets of information, this process of stopping and starting actually makes the tasks take longer and increases the potential for error.

Focused Attention

This is what we call tunnel vision; focusing only on the information that is relevant to the task. Focusing attention in this way causes a loss of other sensual information, hearing being the first to go.

Sustained Attention or vigilance

Refers to situations where attention is maintained overtime. We find it particularly difficult to sustain our attention in this way. An example would be watching an EEG screen in order to make the earliest possible detection of a blip that might signify a change in activity levels.It is particularly difficult to detect infrequent signals of this nature.

Selective Attention

The process by which people find or select something to pay attention to; often referred to as the Cocktail Party Effect when the conversation at the other side of the room can be much more interesting than the one you’re involved in. This is not necessarily a conscious process.

If you are not using a computer within the N3 network you will be able to view a video created by London transport; which will allow you to test your awareness:

London Transport Video (hosted on youtube)

Memory Experiment

Try to remember as many of the words as you can but do not write them down, then go onto the next page:

  • sofa
  • couch
  • stool
  • recliner
  • seat
  • settee
  • chaise longe

Pattern Recognition

A candlestick or two faces?

According to a rscheearch at Cmabridge Uinervtisy, it deosn’t mttaer in waht oredr the ltters in a wrod are, the olny iprmoatnt tihng is taht the frist and isat ltteer be at the rghit pclae. The rset can be a toatl mses and you sitll raed it wouthit porblem. Tihs is bcuseae the huamn mnid deos not raed ervy lteter by istlef, but the wrod as a whole.

Pattern recognition refers to the ability to recognise patterns within clinical characteristics.

The subconcious uses learned knowledge and experience to find patterns; which means that those that are expert in a subject are likely to recognise a pattern more quickly than those who are not because they have more patterns ‘programmed’ in.

Confirmation bias

Because the process is unconscious there is a substantial risk that confirmation bias (attention to data that support the presumed diagnosis and minimising other information) can cause a diagnosis to be missed, because the pattern identified may not be correct.

Types of Error

Internal bias occurs when the Clinician attributes values to a patient or situation and ignores objective evidence to the contrary. Attributed values may come from the Clinician’s:

  • Beliefs
  • View on patient/doctor relationship
  • Level of engagement or interest before patient

External bias can come from the external working environment for example; peer opinion of constraints of time, resources and skills.

Resulting errors can be:

Knowledge based

  • Conscious
  • Overloaded
  • Lack of rules

Skill based

  • Slips & lapses
  • Interruptions
  • Multiple procedures
  • Most familiar sequence

Rule based

  • Bad rule
  • Good rule applied badly
  • Routine
  • Thrill seekers

Why are rules broken?

Situational violations occur when the rules are broken due to pressure to complete the task, or because it is difficult to comply with the rule in the circumstances.

Routine violations occur when rules are deliberately ignored.
An example of a situational violation.

A nurse on night shift lifts an elderly patient who has fallen back into bed, without using a hoist.

Possible reasons

  • The hoist is difficult to don and takes up a substantial amount of time to fit
  • Hoists are not available on every ward
  • The culture of the organisation does not adequately communicate the need to use hoists


In this case the employer may need to:

  • Provide appropriate staff training to address the issue
  • Provide a hoist on every ward
  • Establish a positive safety culture

High Risk Situations

The following factors can make errors more likely to occur in high risk situations:

  • Interruptions and distractions
  • Tasks out of normal sequence
  • Unanticipated new tasks
  • Multiple tasks; attempting to concentrate on too many things at once [8]

Exceeding the speed limit is the most common cause of fatal traffic accidents, although, it is often a deliberate violation that many drivers repeat frequently.

Factors That Make Error More Likely

Factors that make error more likely

  • Fatigue
  • Stress
  • Illness
  • Overload
  • Inexperience
  • Complacency
  • Time Pressure



Anxious or Angry



Apter’s Reversal Theory

This theory describes how a change in the intensity of stimulus can alter how a clinician feels and performs in the working environment.

For example, a junior doctor repeatedly asking a nurse the same questions about a procedure can change the nurse’s reaction from a cooperative emotion to one of irritation and hostility.

If the nurse is filled with unpleasant feelings about the encounter she is likely to try and shorten the encounter or avoid working with that junior doctor in future.

Key Points

Please review the key points from this section:

  1. Conscious thought processes are flexible and allow us to consider 5 – 9 facts at a time; they are slow and effortful.
  2. Automatic thought processes are inflexible and highly practiced; they are fast because they are executed subconsciously.
  3. Experts are better at recognising patterns than beginners; but confirmation bias can cause experts to ignore information that does not conform to their expectations.
  4. Frequent violations can become more severe over time so that the whole culture of an organisation migrates, until an accident or adverse event occurs.


This section of the package addresses a set of human behaviours that are implicated in avoidable clinical error. Explicit awareness of these behaviours facilitates good medical care and may decrease error.

We will explore the following areas:

  • Communication
  • Decision Making
  • Leadership & Management
  • Teamwork & Co-operation
  • Situation Awareness

Communication is the key skill that underpins all of these areas.

Communication Techniques

Structured communication techniques borrowed from other high-risk industries, such as aviation and nuclear power can enable multiprofessional clinical teams to stream-line communication, so that messages can be conveyed consistently and thoroughly.

Structured communication is particularly useful in high-stress situations where immediate attention and response are needed, although it can be used to shape information at any stage.

Closed loop communication

Refers to the practice of repeating back information to confirm that the team member is doing what was asked of them.

A typical exchange would be as follows:

Team member A makes a request, using the name of another team member (Team member B). Team member B responds verbally to confirm or verify the information.

SBAR (SBARD in some organisations, D = Development), is a framework that allows a team member to quickly describe a situation and make a reccomendation about future action. It is commonly used in handover situations.

Situation (Who/where/why)

Background (Summary of patient history)

Assessment ( Clinical information)

Recommendation (advice about what to do next)

The NHS – Institute for Innovation and Improvement provides some useful guidance on using SBAR. This RCEMLearning blog offers more advice on referrals.

Decision Making

Structured decision making techniques are designed to help teams avoid the types of errors covered in section two of this package (pattern recognition, types of error, etc) and encourage conscious thinking in difficult or high risk situations.

Decision making can be:

  1. Analytical / conscious
  2. Pattern Recognition / unconscious – most commonly used, (~80%) becomes more common with experience, because more patterns to compare
  3. Rule based


High risk situations

High risk clinical scenarios

Pattern recognition


  • Critique your own reasoning
  • Think beyond favoured diagnosis
  • Reassess when new information arrives


Memorise the STARR acronym and use it when you need to make a decision.



ASSESS (clinical information)

RESPOND (advice about what to do next)

REVIEW (is it working? Was that the correct decision?)

Leadership & Management

The skills and characteristics that epitomise effective leadership

Effective leadership

  • Completer of tasks
  • Organised
  • High situation awareness
  • Authorative
  • Competant
  • Clear delegation
  • Credible
  • Good communicator
  • Manages workload

Poor Leadership

  • Keeps distance from team
  • Focuses only on task
  • Cannot balance responsibilities
  • Over controlling
  • Avoids Conflict
  • Inconsistent behaviour
  • Demeans Team

Emotional Intelligence

“It is the capacity for recognising our own feelings and those of others, for motivating ourselves, and for managing emotions well in ourselves and in our relationships.” [9]

The model of emotional intelligence has five components:

  • Self awareness
  • Self regulation
  • Motivation
  • Empathy
  • Adeptness in relationships

Teamwork & Co-operation: Personalities

Personalities behave differently. Understanding your own personality can help you to communicate effectively with others.

Myers Briggs model of personality consists of four dichotomies:

1. Extraversion or Introversion Where you draw your energy from
2. Sensing or Intuition What type of information you trust
3. Thinking or Feeling How you use that information to make decisions
4. Judgment or Perception How you structure the external world

 You can find out about your Myers Briggs type by taking this test.

Key Points

Please review the key points from this section:

  1. A good team member supports the leader, but is assertive when necessary, is calm under stress and puts the team before themselves.
  2. An effective leader communicates well with the whole team and delegates tasks efficiently.
  3. Emotional intelligence has five components: self awareness, self regulation, motivation, empathy and adeptness in relationships.
  4. Situation awareness refers to our understanding of what is happening; a loss of situation awareness is a disconnection between reality and perception.
  1. Framework for observing and rating Anaesthetists’ Non-Technical Skills (ANTs) System Handbook v1.0. Aberdeen: University of Aberdeen. 2012.
  2. Sari AB, Sheldon TA, Cracknell A, Turnbull A, et al. Extent, nature and consequences of adverse events: results of a retrospective casenote review in a large NHS hospital. Qual Saf Health Care. 2007 Dec;16(6):434-9.
  3. Columbia Accident Investigations Board Report Vol 1 2003.
  4. Harmer M. Independent Review on the care given to Mrs Elaine Bromiley The Case of Elaine Bromiley. 2005.
  5. Reason J.T. (1990). Human Error. Cambridge University Press.
  6. Edwards, E. (1972) Man and Machine: Systems for Safety. Proceedings of British Airline Pilots Association Technical Symposium, British Airline Pilots Association, London, 21-36.
  7. Wierenga PC, Lie-A-Huen L, de Rooij SE, et al. Application of the Bow-Tie model in medication safety risk analysis: consecutive experience in two hospitals in the Netherlands. Drug Saf. 2009;32(8):663-73.
  8. Loukopoulos et al. The Multitasking Myth Handling Complexity in Real-World Operations. Routledge, 2009.
  9. Goleman D. Working with Emotional Intelligence. Bantam books, 1998.
  10. M. R. Endsley, “Situation awareness global assessment technique (SAGAT),” Proceedings of the IEEE 1988 National Aerospace and Electronics Conference, 1988, pp. 789-795 vol.3, doi: 10.1109/NAECON.1988.195097.