Fast Thinking in Emergency Medicine

Cognition in Emergency Medicine

Why is this topic important?

  • Medicine is delivered by ‘humans’ to ‘humans’
  • Inevitably this is an error prone interaction
  • Tendency toward error is amplified by time pressures as well as high levels of emotional and physical stress
  • We have a lack of education on how to ‘think about thinking

ACEM 2015 – Emergency Physicians need to be expert diagnosticians of the patient AND themselves


The ACEM 2015 Conference – International Experts at the Symposium on Metacognition

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How do Doctors make decisions?

  • Experienced clinicians are generally excellent “pattern recognisers
  • Pattern recognition can be developed further with effort but it is an intrinsic human skill…
What do you see in this picture? 
  • When asked by a non-expert to explain their actions experts often cannot articulate why they ‘do something’ (unconscious competence).  Experts operate at the top of ‘Miller’s Pyramid‘:


  • As we become more experienced when we start seeing a new patient we subconsciously weigh the probabilities of the most likely diagnoses.
  • Diagnostic probabilities will change based on the information you gather and the tests you do.  Working through ‘balance of probabilities’ can be done mathematically.  This systematic approach was described by Thomas Bayes (1701-1761). The process of “Bayesian” Reasoning describes a way we think about probabilities.
  • In theory, working through this type of systematic reasoning should lead us to accurate and reproducible conclusions.  However, in real life we are NOT good at knowing the probabilities and even worse at weighing these probabilities.

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How do different staff think?

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The Medical Student

  • Uses analytical thinking rather than intuition
  • The student or junior doctor when observed in their approach often appears to be in ‘Long case mode‘.
  • Typically, the inexperienced practitioner is deliberate with a great attention to detail.  They are likely to have thought through the steps (without necessarily coming to the correct conclusion).
  • The student or inexperienced doctor cannot always recognise a ‘classic’ pattern.  On occasion, they may fail to recognise either the obvious diagnosis or think of “ROAST” (‘ruling out all significant things’)

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The Experienced Doctor

  • Pattern recognisers
  • Use Intuition rather than analytical thinking
  • Experienced clinicians mistakes are almost never ‘knowledge based’.
  • Errors are more commonly associated with ‘bias‘, communication or teamwork.

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Teamwork and communication can be improved though awareness and training.

Reducing errors requires us to think about the way we think.  This process is known as ‘metacognition‘.

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Cognitive Bias

Pat Croskerry has famously described ‘cognitive biases’ in the context of Emergency Medicine.  Cognitive bias can lead to failure to correctly weigh all the available information about the patient.  This can lead to sub-optimal clinical reasoning.  Time pressure, social cues, emotion, tiredness and hunger can all add to our potential bias

Emergency Department biases include:

  • Confirmation Bias – positive information supporting your current position is overly valued whereas new negative information than may refute your current position is often either ignored or discarded.


  • Premature Diagnostic Closure has been glamorised by the likes of Hugh Laurie’s ‘House’ character. Dr House (pictured below) frequently makes obscure diagnoses with minimal information.  In reality this is a highly dangerous error prone strategy when applied to our patients in the Emergency Department.  This bias is some times referred to as search satisfaction


  • Availability Bias – refers to our perception that a diagnosis is more likely to be correct if it is commonly occurring or it readily comes to mind in the light of our recent experience.
  • Anchoring Bias – refers to our tendency to focus on to the features of the main presentation and narrow down too early.  For example, a patient who has been put in the eye room must have ‘an eye problem’ or an patient triaged as ‘anxious’ must have a ‘psychological disorder’.

Be humble – 93% of motorist think they are better than average drivers – How many doctors think they are better than average and  as a result jump too quickly to their diagnosis?

More Cognitive BiasesClick Here

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Some Common Pitfalls leading to Cognitive Errors

  • An unwillingness to use interpreters is a classic problem in the ED.  This can lead to a breakdown in communication with patient and their families. By using an interpreter, not only will you gather useful information about the patient, but you will also be able to give reliable advice to the non-english speaking family. Furthermore, interpreter use is associated with greatly increased patient satisfaction.
  • Cognitive Bias may increase if we spend less time with the patient. Therefore, spend MORE time with the patient and get a complete picture of what is going on.
  • Relying on our ‘medical expertise’ alone will lead an increase in our error.  Human fallibly (being hungry, angry, late or overly tired) can be a simple cause of error – take your breaks and ensure your colleagues take their breaks too.


  • Use helpful decision “rules” but apply them to your individual patient mindfully.
  • Handover with bias can lead to a false diagnostic momentum:
    • Nurse: ‘can you review and send home the anxious lady in bed 6 with the hyperventilation, she’s pretty anxious.
    • You: ‘Sure, I’ll take a look and maybe send them home
    • Nurse ‘Thanks Doc – the department’s hectic tonight so lets get her home ASAP
    • Maybe the patient does have a benign anxiety attack or maybe she has a PE or DKA?  One thing is for sure, you may not pick up on cues to a serious underlying problem if you carry in a significant pre-assessment bias.
  • A lack of awareness of potential cognitive errors will lead to you missing important pathology regardless of your level of medical expertise.

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Further Reading