The bias of the question posed: a diagnostic "invisible gorilla".

Posing a question can introduce a powerful bias into the diagnostic process. A clinical case is presented to demonstrate how a colleague's diagnostic question can focus the clinicians' attention on one detail, distracting and blinding them even to the most obvious and important clinical findings. This "inattentional blindness" is similar to the phenomenon demonstrated by Simons in the famous "invisible gorilla" psychological experiment. As much as practical, clinicians should attempt to assess referred patients independently before considering previous clinical information; including the question/s they were asked.