How to think like a consultant at medical school.

Novices and experts think differently. Consultants and senior doctors are much more likely to make quicker, safer and all-round better decisions for patients than those with less experience, like medical students. It all comes down to the way that consultants think versus junior colleagues.

This is also the case between junior and senior medical students. Those in their final year are more likely to think differently than those fresh into their clinical years.

It sounds obvious, but have you ever thought of why? Novices (like medical students) require more systematic ways of thinking, whereas experts can trust in their heuristics.

We’re going to go into how you can intentionally improve upon your clinical decision-making skills early, to help you perform better in your medical school exams.

Sometimes we need to slow down to speed up

🥜Article in a nutshell

  • The leading theory on how we make decisions are described by System I & II thinking
  • System I is instinctive, fast and prone to error.
  • System II is systematic, but slow.
  • Experts spend more time in system I thinking, but can easily jump between both systems.
  • Medical students can build up their system II knowledge and create opportunities to practice system I

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🤔What is System I vs. System II thinking?

Daniel Kahneman is an Israeli-American psychologist notable for his work on the psychology of judgment and decision-making, as well as behavioral economics, for which he was awarded the 2002 Nobel Memorial Prize in Economic Sciences.

Kahneman divides thinking into two systems: “System One” and “System Two” – you can read about this in great detail in hist best-seller Thinking, Fast and Slow.

In this article, we’re going to cover how you can train your brain to think like an expert using these principles.

System I

The mode of intuition.

System I thinking is based on heuristics. It’s effortless, unconscious and automatic. Heuristics are simple rules that we use to make decisions quickly. They’re based on our previous experiences and they help us save time and mental energy. We often don’t even realize that we’re using them. System I thinking takes the steering wheel >95% of the time in our daily lives.

Examples include:

  • Quickly turning to the source of a loud sound
  • Making a disgusted face when shown a picture of your hospital rota
  • Knowing the answer to 2+2
  • Judging the distance between objects when walking

When you’ve built up a mental library of heuristics, you can trust your System I thinking to automatically make good decisions for you. This is why experts can make quick and accurate decisions without having to think through all the options. They’ve internalized the rules of thumb (heuristics) that they need to make good decisions.

Like with everything, it has its cons as well – it’s clumsy, it’s too keen, it can lead you astray, and is thwarted by bias (it’s a cognitive bias after all).

System II

The systematic mode.

It’s slower, more deliberative, and more logical. This is the kind of thinking we do when we solve a math problem or read a long article. It kicks in when System I runs into difficulty analysing a situation. It requires mental effort and it’s tiring. We can only sustain System II thinking for so long before we need a break.

System II works as a fail-safe to ensure you’ve thought through all possible options and is a methodological approach to decision making.

Examples of System II:

  • Judging the validity of a logical argument
  • Comparing the features of an iPhone versus and iPad
  • When counting the number of vowels in this sentence
  • Tuning into the sound of a specific voice in a crowded room
  • Trying to understand the clotting cascade

In summary, system one thinking is fast, automatic, and emotional. System II thinking is slower, more deliberate, and more logical.

🤌How it relates to medical students.

Thinking fast and slow underpins how decision-making differs between the novices and the experts. The biggest difference is that the experts have built up a large repertoire of heuristics (mental shortcuts) that they can rely on to make quick and accurate decisions. This is why consultants can appear to be “thinking on their feet” or “acting on instinct” when deciding on patient management. They’ve internalized the rules of thumb that they use.

Consultants will also have a solid system II from their familiarisation of subject knowledge they’ve acquired over their career. If they have trouble aligning decision to what they’ve seen previously, their robust system II will kick in to help them land on a decision.

Let’s walk through a medical example…

🤌An example of system I and II in action.

Let’s take the example of approaching a patient with chest pain.

“A 62-year-old gentleman. Presenting complaint of central sudden onset chest pain. PMH: peripheral vascular disease, HTN, T2DM. DH: amlodipine, atorvastatin, isosorbide mononitrate and GTN PRN. Social history: Smokes 12 cigarettes a day, drinks occasionally”

Q: What’s the first differential that comes to mind?

Now without even knowing the details of the history, if you’ve jumped straight to MI (or any acute coronary syndrome) then you’re on the right track. You’ve made a shortcut. That’s your heuristics at play.

If however, you’re a first-year medical student you may not have even noticed the strong suggestive features. Or perhaps you did, but you were unclear of whether you were missing something.

Perhaps you got it straight away, but what if I were to ask you – “what else could it be?”. Eventually you’ll reach a stage where it doesn’t come straight to your mind and you’ll turn on your system II switch.

So how would you approach this if it didn’t come to you straight away (or if you didn’t have enough experiences racked up to trust your intuition)? You’d have to cast the net more widely. This is where system II comes in.

A system II approach requires a systematic response. In this context, we can rely on categorization. One way you may choose to categorize chest pain is as follows:

  • Cardiovascular: acute coronary syndrome, coronary case spasm, aortic dissection, pericarditis
  • Respiratory: pulmonary embolism, pneumonia, pneumothorax, pleural effusion
  • Gastrointestinal: GORD, achalasia, peptic ulcer disease, oesophagitis
  • Musculoskeletal: rib fracture, muscular sprain, costochondritis, cervical radiculopathy
  • Misc: anxiety

If you’re thinking in this way, you’re thinking system II. Chest pain is a great example. Every time you approach a patient with chest pain, try to recall the categories that fit in with this presentation. The more familiar you are, the faster you’ll be able to think through your differentials.

👏How to think fast and slow to improve your clinical decision-making skills.

Lets take the example of being in an MCQ exam. System I is your gut feeling – the answer based you’ve seen or read before. System II is your proof checking mechanism – your chance to think of the other things it could be and to rule out the wrong answers.

During medical school I would attempt to build a robust system II as a foundation by covering content and intentionally categorising differentials and lists of information (where applicable). When revising for practical exams for example, I’d ask myself, “how can I categorise shortness of breath by its causes”. The more you do it, the easier you’ll be able to access your system II thinking. As your system II approach becomes more robust, you’ll find confidence in using your system I first instinct approach to answering quesitons, with the safety of falling back to system II to cross check your answers.

Building System 2 – categorise as much as possible

  • Prime the knowledge with reading and questions banks
  • categorize the differentials of every presentation you can think of
  • Reflect on the rationale behind clinical decisions for the patients you see on placement
  • Engage in case-based discussions
  • Use the Feynman technique – if you don’t know what I mean, then check out this article.

Building system I knowledge – be put on the spot as much as possible

  • Put in the repetitions with practical exams (like OSCES/PACES)
  • build your clinical acumen by seeing patients in the acute setting and on the wards
  • Practice exam questions in bulk with online question banks
  • Practice responding to direct questions on the spot by being grilled by a consultant or med student.


Thinking fast and slow can help you perform better in medical school. Novices need to think more systematically, while experts can trust their heuristics. Being aware of these principles can help you train your brain to be more effective at learning new information.

Practicing system II thinking can help you build up your knowledge base so that you can make intuitive decisions later on. Ultimately, the goal is to be able to flip between system I and system II thinking. You can put system I into practice with question banks, being grilled by your peers and seniors, or through simulation training.

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