Availability bias is related to the diagnosing of a disease that easily comes to mind. We tend to diagnose what we’ve seen in the most recent past. An example would be diagnosing a recent gall bladder surgery patient with a DVT because several months ago while on call you had a patient with that same complication. Another example would be diagnosing a patient with influenza at the height of the flu season, and as a result, missing the patient’s pulmonary embolism.

Confirmation bias is when you “see only the landmarks you expect to see and neglect those that should tell you that in fact you’re still at sea [5]. Your skewed reading of the map ‘confirms’ your mistaken assumption that you have reached your destination.” It is the tendency to seek confirming evidence rather than looking for other findings that would disprove the diagnosis. In the above flu case, you might latch on to the temperature as proof of an infection and gloss over a normal chest X-ray. In the anesthesia world an example would be the repeating of arterial measurements and changing of cuff sizes in an effort to get a reassuring reading rather than recognizing the hypotension is real [12].

A framing bias occurs when a diagnostician is misled or influenced by the way a problem or patient is presented. It can occur when you get a consult: “Can you see the drunk who’s in the ER and rule out an acute abdomen?” This consult might lead us to a less than thorough evaluation. This also comes into play when you are presenting a patient with a difficult choice. The statements “this surgery has a 90 % failure rate” will result in fewer patients choosing surgery than a frame of “this surgery has a 10 % cure rate.

An attribution bias is an interpretive judgment that is made by some behavior that is observed. This might occur when one is taking care of an addicted patient with somatic complaints. The physician might be influenced by his emotional bias and miss the infection because of the attribution to a withdrawal syndrome. Emotion can affect how you reason in a variety of ways. The amygdala controls the deep emotional responses and works directly with the decision areas of the frontal cortex [13]. Many of these biases are tied to our emotional state.

Search satisficing occurs when the physician calls off the search for a problem when they have found an abnormality. Crosskerry asks the teaching question [14] “what is the most common missed fracture?” The answer is, of course, “the second fracture.” Every year several fractures are missed by orthopaedists or ER doctors because they call off the search for a fracture after finding the first one.

Hindsight bias is when the knowledge of the outcome influences a true appraisal of what actually happened. This is informally known as the retrospectroscope. One may overestimate what they did at the time of an event, what they knew and what they thought. Or one may be devastated when they present and are criticized in a morbidity and mortality conference.

An authority bias would be accepting a diagnosis without question that had been made by a senior, more esteemed colleague. Perhaps the patient has had extensive evaluation at the university for their abdominal pain. In this situation a clinician might assume further evaluation would be of no benefit. This is also related to the ying yang bias, as in “the patient has been worked up the ying yang and we shouldn’t repeat the workup.”

Finally, there is the most common and troublesome pair of all biases, anchoring bias and its close relative premature closure. Anchoring is “a shortcut in thinking where a person doesn’t consider multiple possibilities but quickly and firmly latches on to a single one, sure that he has thrown his anchor down just where he needs to be” [5]. Premature closure is where you accept a diagnosis early and do not pay attention to further vetting that would allow an alternative diagnosis. An example might be an orthopaedist who sees a post op total knee replacement and assumes the swelling is typical of what he sees post op and misses a DVT. The fact that the patient is on anticoagulation is the confounding issue that leads him away from a DVT diagnosis. The data on anticoagulation is clear that even with best practice, anticoagulation DVTs will occur in post op orthopaedic settings. Another example would be in the renal colic patient who is writhing in pain as did the last three renal colic patients you’ve encountered and you miss the aortic aneurysm dissecting into the renal artery. You anchored or prematurely closed on your first impression. These are the bane of System 1 thinking. Heuristics serve a clinician well as they race through the day and are part of the economy of thought that lead to a smooth practice, but anchoring on your first impression leads to misses that are the price of cognitively cutting corners.