system one and

system two

Making decisions is as easy or as hard as you want it to be

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pat croskerry,

an author with whom you should get familiar, describes critical thinking in medicine as an iterative process consisting of two systems. System one is quick, easy and often wrong. System one is Lucy assuming that the rustling is a tiger. It’s also when you look at a patient who is in his sixties, has a pack of cigarettes in his shirt pocket and is “tripodding” and “pursed-lip breathing” in the emergency department and you immediately know he has an exacerbation of COPD. So what’s the problem? It turns out that System One thinking is often subject to COGNITIVE BIAS

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System Two

is more thoughtful, harder, and more accurate. After making your initial guess at a diagnosis you think of all the associations of that diagnosis checking them against your patient. Does everything fit? Wait. How old did he say he was? He looks like 60 but he’s only 35. I’ve never seen that before. What looks like advanced emphysema but occurs in a much younger patient? Could he have alpha 1 anti-trypsin deficiency?

THis, then, is about critical thinking. we are expecting you to use critical thinking skills and apply it to your clinical skills. even when you think the diagnosis is clear, ask yourself:

•What else could this be?

•What finding does not fit with my diagnosis?

•Could there be multiple processes going on at once?

•Is there any other reason I need to slow down and reconsider my approach (Milestone PBLI 4: Learning at the point of care)?