The researchers constructed two separate résumés: one for a highly qualified candidate with six years of experience, and one for a novice candidate about one year out of college. For each résumé, they created three different cover letters: one for a candidate with no disability, one for a candidate who disclosed a spinal cord injury and one for a candidate who disclosed having Asperger’s syndrome, a disorder that can make social interaction difficult.

Earlier studies had suggested that better qualifications might help disabled candidates overcome employment discrimination, but the researchers found the opposite. Employers were about 34 percent less likely to show interest in an experienced disabled candidate, but only about 15 percent less likely to express interest in a disabled candidate just starting out his or her career. (The latter result was not statistically significant.)

“We created people who were truly experts in that profession,” said Mason Ameri, a Ph.D. candidate with the School of Management and Labor Relations at Rutgers, who was another one of the researchers. “We thought the employer would want to at least speak to this person, shoot an email, send a phone call, see if I could put a face to a name.” For the gap between disabled and nondisabled to be larger among experienced candidates than among novice candidates, he said, came as a surprise.

Mr. Ameri and his colleagues speculated that the steeper drop-off in interest for experienced disabled candidates arose because more experienced workers represent a larger investment for employers, who must typically pay such workers higher salaries and who may anticipate the employment relationship lasting longer. Experienced workers are also more likely to interact with clients on a regular basis. Regardless of whether these concerns are legitimate, said Dr. Schur, “employers see these people as riskier.”

The researchers found that the decline in interest in disabled workers was roughly the same whether the disability was a spinal cord injury or Asperger’s. If it were the result of a specific concern — for example, that candidates with Asperger’s would have a hard time interacting with clients, or that employers would have to build ramps for workers in wheelchairs — rather than a general bias against people with disabilities, it is unlikely that people with such distinct disabilities would have experienced a drop-off in interest of about the same magnitude.

The study showed that the Americans With Disabilities Act, the 1990 federal law banning discrimination against those with disabilities, appeared to reduce bias. The lack of interest in disabled workers — and especially in the rate at which they were called back for an interview — was most pronounced in workplaces with fewer than 15 employees, the study found. Businesses that small are not covered by the federal law.