Recruiters who shift their hiring criteria after learning the gender of job applicants are a major reason for sex discrimination enduring in the workplace despite the existence of legislation and policies intending to stamp it out.
Studies by researchers at Yale University published in the journal Psychological Science have revealed how failing to establish clear hiring criteria at the beginning of the recruitment process can put women at a disadvantage.
"The question we wanted to answer is how, in this system of meritocracy where people are supposed to be judged on the basis of their personal credentials and accomplishments, the reality of discrimination continues," said Geoffrey Cohen, associate professor in the Department of Psychology at Yale and co-author of the study with doctoral student Eric Uhlmann.
What the researchers found in three studies was that people making hiring decisions construct criteria of merit congenial to the particular strengths of members of the advantaged or dominant group.
Those participants who felt most strongly that they had been objective actually proved the most biased, Cohen added.
In one study, participants were asked to hire a new police chief, for which there were both male and female applicants.
Some of the applicants had more on-the-job "street" experience, while others had stronger educational backgrounds.
"When people were evaluating male applicants they shifted the job criteria to emphasise the importance of whatever credentials the male applicants happened to have," Cohen said.
They showed no such favouritism when evaluating female applicants, and even tended to denigrate the importance of the female applicants' areas of strength, he added.
In a second study, participants were asked to hire a women's studies professor. In this case they based their hiring criteria on whatever the particular strengths of the female applicants happened to be.
The third study revealed that gender discrimination was eliminated through the simple intervention of having people commit to hiring criteria before they reviewed an applicant's credentials.
"People who make hiring decisions should decide what criteria are important to a particular job before the interviews so that there is no room to manoeuvre later on," Cohen said.
"That kind of pre-commitment may help to reduce discrimination."