Definitions abound in the medical error and patient safety literature, with subtle and not-so-subtle variations in the meanings of important terms. We have tried to adopt the most straightforward terminology, with definitions that enjoy the widest use.
Anchoring Error (or Bias):
Refers to the common cognitive trap of allowing first impressions to exert undue influence on the diagnostic process. Clinicians often latch on to features of a patient's presentation that suggest a specific diagnosis. Often, this initial diagnostic impression will prove correct, hence the use of the phrase
in some contexts, as it can be a useful rule of thumb to "always trust your first impressions." However, in some cases, subsequent developments in the patient's course will prove inconsistent with the first impression. Anchoring bias refers to the tendency to hold on to the initial diagnosis, even in the face of disconfirming evidence.