There are plenty of reasons why medical students aren’t choosing primary care as careers.

Lack of role models.  Perception of professional dissatisfaction.  High burnout rate among generalist doctors. Long, uncontrollable hours.

But what about salary? Until now, the wage disparity between primary care doctors and specialists has only been an assumed reason; the evidence was largely circumstantial.  After all, the average medical school debt exceeds $160,000, so why not go into a specialty that pays several times more, with better hours?

Thanks to Robert Centor, there’s a study published in Medscape that shows how money affects career choice among medical students.

Here’s what they found:

Sixty-six percent of students did not apply for a primary care residency. Of these, 30% would have applied for primary care if they had been given a median bonus of $27,500 before and after residency. Forty-one percent of students would have considered applying for primary care for a median military annual salary after residency of $175,000.

And in conclusion,

U.S. medical students, particularly those considering primary care but selecting controllable lifestyle specialties, are more likely to consider applying for a primary care specialty if provided a financial incentive.

Money matters. There should be no shame for new doctors to admit that. After all, they’re human too, and respond to financial incentives just like anyone else. And when most medical students graduate with mortgage-sized school loans, salary should be a factor when considering a career.

Of course, primary care’s plight has been well documented during the health reform debate. And, to the Affordable Care Act’s credit, it gives a token increase to generalist provider reimbursement. But it’s nowhere near enough to overcome the fiscal disparity when compared to most specialists’ salaries, and thus, will make little impact going forward.

Combined with the fact that primary care continue to struggle under weight of worsening bureaucratic obstacles, time pressures, and the prospect of seeing tens of millions of newly insured patients in 2014, there’s little hope that the current generation of medical student will stem the tide of primary care’s demise.

Kevin Pho is an internal medicine physician and on the Board of Contributors at USA Today.  He is founder and editor of KevinMD.com, also on Facebook, Twitter, Google+, and LinkedIn.