A patient walks in with fatigue, mild weight loss, and “normal” basic labs. The first thought based on the most recent similar case is “probably stress.” And just like that, the diagnostic path quietly narrows. 
This is where clinical reasoning becomes less “algorithmic” and more human than we admit.
Anchoring bias: The first impression sticks.
Once a working diagnosis forms, everything else is interpreted through it even when new clues don’t fully fit.
Confirmation bias: We look for what supports our hypothesis, and unintentionally filter out what doesn’t.
Availability bias: The most recent or dramatic case feels more likely than it statistically is, shaping decisions in subtle ways.
Studies in diagnostic medicine suggest that cognitive errors contribute to a significant proportion of diagnostic inaccuracies, especially in time-crunched outpatient settings where rapid pattern recognition takes over deliberate analysis.
The brain constantly tries to simplify complexity. Even experienced doctors are not immune. In fact, experience sometimes strengthens pattern recognition so much that it can unintentionally reinforce bias instead of reducing it.
My takeaway (and maybe yours too):
Good clinical practice isn’t just about knowing more it’s about questioning what your mind is too quick to conclude.
Because sometimes the hardest diagnosis to question… is the first one that felt right. 
MBH/PS