Demystifying cognitive bias in the diagnostic process for frontline clinicians and educators; new words for old ideas.

Diagnostic error is a pervasive problem in healthcare with approximately one-third of adverse events in hospitals attributed to a failure in the diagnostic process. Cognitive biases are systematic, often unconscious, automatic patterns of thought that sometimes skew thinking and are considered a major contributor to diagnostic error. More than 100 different biases have been described that affect clinical decision-making, and the challenge for educators and clinicians is bringing the conceptual knowledge of cognitive bias to the bedside in an applicable and useful way to mitigate the effects of cognitive bias in diagnosis. The language that is commonly used around cognitive bias is technical in nature, often with complicated and nuanced descriptions, so developing a clear understanding of cognitive bias is a task that needs sophisticated language and memory skills as well as clinical reasoning skills. A novel language approach to learning and talking about biases in medicine is to use idioms, short phrases with a particular meaning that differs from the meaning of each word on their own, to simplify the terminology and improve recognition of cognitive bias at the frontline. We present 'The Idiom's Guide to Cognitive Bias', a Table that lists 21 common cognitive biases in the diagnostic process, and defines each, offering a healthcare example and possible explanation for why each occurs. The benefit of The Guide is its practical approach to reinforcing cognitive and medical concepts through the synergy of language and imagery and to demystify cognitive bias in the diagnostic process.