LeBron James exploded past his defender and raced towards the lane.  Serge Ibaka, the Thunder’s mountainous center, planted his feet and raised his hands straight up into the air.  LeBron ducked his left shoulder and plowed right into Ibaka, who went crashing backwards into a nearby cameraman.

Offensive foul?

Maybe if it had been the first quarter.  But given that this was the last minutes of a tightly fought game, the referees chose to restrain themselves, not wanting the game to turn on their actions.  Was this even controversial?  Not a bit.  In such situations, announcers typically applaud the non-call, intoning platitudes like “this game should be decided by the players.”

In their excellent book Scorecasting, Tobias Moskowitz and L. Jon Woertheim explore the psychology of sports through exhaustive and yet entertaining analyses of all kinds of topics that have fueled many a heated bar stool argument.

Are referees biased against your favorite team?  According to their analyses, they are biased against your team only if it is playing an away game.  Turns out that their unconscious desires to please fans cause referees and umpires to back away from controversial calls that will raise the crowd’s ire.

One of the most fascinating chapters in the book involves what the authors call “whistle swallowing.”  All else equal, referees and umpires avoid sins of commission over sins of omission, a preference for inactivity nicely summarized by veteran NBA referee Gary Benson: “It’s late in the game and, let’s say, there’s goal tending and you miss it.  That’s an incorrect non-call and that’s bad.  But let’s say it’s late in the game and you call goal tending on a play and the re-play shows it was an incorrect call.  That’s when you’re in a really deep mess.”

Those of us who study medical decision making are well aware of this preference for inactivity.  We see it every time a patient chooses to forego a flu shot out of fear that they will experience side effects from the vaccine, even though the chance of side effects pales in comparison to the vaccine’s benefits.  In one study, a substantial number of people said they would rather accept a 10% chance of dying from the flu than receive a vaccine that carried a 5% risk of causing a fatal side effect.

This powerful phenomenon, this omission bias, causes baseball umpires to enlarge the strike zone by 93 square inches on 3-0 counts, so they won’t influence the game by walking the batter.  It also cause NBA referees to disproportionately call loose ball fowls on non-stars, so the decisions won’t take stars like Kobe and Carmelo out of the game and thereby influence the outcome.

Those of us who work in medical decision making know this preference for inaction well.  But we also know some major exceptions to this behavior.  Chief among them: the way physicians think about action and inaction when contemplating ways they can avoid being sued for malpractice.

I have encountered this thinking scores of times when speaking to medical audiences about the importance of controlling healthcare spending.  In my talks, I tell stories of testing run amok, and of procedures ordered in an almost willy nilly fashion.  Inevitably an audience member, a physician, will rush to the microphone at the end of my talk and vehemently explain: “That’s fine to control costs and all.  But meanwhile I’m going to get sued because my patient develops a tumor that I didn’t find because I didn’t order a CT scan six months ago when they had milder symptoms.”

According to health economists, practicing defensive medicine adds billions of dollars to our healthcare budget, with physicians ordering low yield tests so the patients will realize their doctors have done everything possible to explain every one of their symptoms.

I understand the psychological power of lawsuits.  Indeed, some companies make a decent living helping physicians overcome the emotional trauma of being sued.  Even unsuccessful litigation can take an emotional toll, causing doctors to question their own judgment and to lose trust in their patients.

But why does fear of litigation necessarily turn into preference for action?  After all, that unnecessary CT scan could reveal a suspicious “density,” which leads to an unnecessary biopsy, the latter test potentially causing an unexpected complication.  Isn’t it possible that your patient will sue you for chasing after imaginary shadows?  What evidence is there that aggressive physicians—those who order lots of tests and procedures—are sued any less often than their more parsimonious colleagues?

What we have here—both for NBA referees and experienced physicians—is the triumph of psychology over professional expertise.  Preference for both action and inaction needs to be squelched, in favor of preference for the truth.  Professionals need to become more aware of their own biases, so they can better sort out offensive fouls and defensive medicine.

Peter Ubel is a physician and behavioral scientist who blogs at his self-titled site, Peter Ubel and can be reached on Twitter @PeterUbel.  He is the author of Critical Decisions: How You and Your Doctor Can Make the Right Medical Choices Together.