“The noncognitive, personality domain is an untapped area for medical school admissions,” said Deniz S. Ones, a professor of psychology at the University of Minnesota and one of the authors of the study. “We typically address it in a more haphazard way than we do cognitive ability, relying on recommendations, essays and either structured or unstructured interviews. We need to close the loop on all of this.”

Some schools have tried to use a quantitative rating system to evaluate applicant essays and letters of recommendation, but the results remain inconsistent. “Even with these attempts to make the process more sophisticated, there is no standardization,” Dr. Ones said. “Some references might emphasize conscientiousness, and some interviewers might focus on extraversion. That nonstandardization has costs in terms of making wrong decisions based on personality characteristics.”

By using standardized assessments of personality, a medical school admissions committee can get a better sense of how a candidate stands relative to others. “If I know someone is not just stress-prone, but stress-prone at the 95th percentile rather than the 65th,” Dr. Ones said, “I would have to ask myself if that person could handle the stress of medicine.”

While standardized tests like the MCAT and the SAT have been criticized for putting certain population groups at a disadvantage, the particular personality test used in this study has been shown to work consistently across different cultures and backgrounds. “This test shows virtually none or very tiny differences between different ethnic or minority groups,” Dr. Ones noted. Because of this reliability, the test is a potentially invaluable adjunct to more traditional knowledge-based testing. “It could work as an additional predictive tool in the system,” she said.

One perennial question that personality testing could help to answer is whether hard work can make up for differences in cognitive ability. “Some of our data says yes,” Dr. Ones said. “If someone is at the 15th percentile of the cognitive test but at the 95th percentile of conscientiousness, chances are that the student is going to make it.” That student may even eventually outperform peers who have higher cognitive test scores but who are less conscientious or more neurotic and stress-prone.

But these standardized tests, personality or cognitive, can be useful only after medical schools, and the public they serve, decide what characteristics are most important for the next generation of doctors. “If a medical school is all about graduating great researchers, then I would tell them not to weigh the results of the personality test that heavily,” Dr. Ones said. “But if you want doctors who are practitioners, valued members in terms of serving greater public, then you have to pay close attention to these results.”