Many parents love to brag about their children. Some even note their children’s existence on their resumes. Perhaps they shouldn’t.

According to research presented by two Cornell University sociologists at a recent Wharton conference, mothers suffer when competing for jobs against similarly qualified fathers and childless men and women. The conference, entitled “Careers and Career Transitions: New Evidence for a New Economy,” was organized by Wharton’s Center for Human Resources and sponsored by career transitions firm DBM.

Additional research presented at the conference offered interesting observations on another group in the workplace — smokers. According to scholars from Columbia University and Barnard College, smokers are paid less on average than other workers. The researchers suggest that employers may be right to pay smokers less because people who smoke may be less willing to invest time and effort in career advancement than nonsmoking colleagues. 

Beyond their exploration of wages and workplace dynamics, the two papers seem dissimilar, but both try to sift through a stubborn problem in human-resource economics: Some people make more money than others and, even after controlling for factors like education and experience, it is often not clear why. Supervisors are usually willing to provide justifications for individual workers. But at the level of aggregate data, the disparities remain a puzzle.

Fatherhood Helps; Motherhood Doesn’t

Shelley Correll and Stephen Benard, the Cornell sociologists, believe discrimination against mothers may play a role. They set out to test their hypothesis with an experiment.

They created resumes and human-resource department memos for candidates for an executive-level marketing job in a communications startup. The resumes contained effectively identical qualifications. Correll and Benard then added features to distinguish the candidates. On some resumes, they indicated that the candidate served in a parent-teacher association. On others, they said he (or she) served in a neighborhood association. The HR memos also included notations on whether a candidate was a parent or married. Correll and Benard used names to flag candidates’ gender. Some were given typically male names while others received typically female ones.

The scholars hired college students to act as screeners, telling them that the hiring company marketed to young people and thus wanted their input in its hiring decisions. They gave each student a pair of resumes — two women or two men; one a parent, the other not — and instructed them to rank the candidates and even propose starting salaries. They also asked them to suggest how many late arrivals at work a candidate should be allowed before being penalized.

On every measure but one, mothers scored lower than everyone else. (On the number of late arrivals allowed, they tied with men without kids.) Mothers were ranked as less competent and committed and least likely to be promoted. And they were offered lower starting salaries.

Interestingly, the students ranked women without children as the most qualified on several measures, giving them the highest scores for commitment, competence and likelihood of promotion. Even so, childless women weren’t offered the highest starting salaries. Those went to fathers, who also were rated as most likely to be promoted. Childless men didn’t fare as well. They beat mothers on most measures but fell behind childless women on every measure but one. Maybe the raters assumed they would spend too many nights out carousing.

In short, it appeared that fatherhood helped job candidates while motherhood hurt them.

Correll and Benard interpret their results as showing that a “motherhood penalty” exists in hiring. (Childless men might argue that there is a “swingers” penalty, too.) “To the extent that employers view mothers as less committed to their jobs and less ‘promotable,’ the glass ceiling women face could be, in part, a motherhood ceiling,” they write in their paper titled, “Getting a Job: Is There a Motherhood Penalty?” The male and female applicants “who were evaluated in this experiment were exactly equal,” they add. The fact that “parental status disadvantaged only female applicants is strong evidence of discrimination.”

Brigitte Madrian, a Wharton professor of business and public policy who moderated the session in which Correll presented her research, didn’t draw such an unequivocal conclusion. Calling Correll and Benard’s results plausible, she cautioned that their findings came from an experiment with undergraduates. “An obvious extension would be doing it with hiring professionals,” she says. (In their paper, Correll and Benard note that, in prior research, undergraduates’ ratings of job candidates have mirrored those of professionals.)

Madrian also pointed out that the raters had hewed to conventional workplace wisdom. “There’s a perception that young men are a little less reliable than young women and that fatherhood settles men down. And there’s a perception that women with children are less reliable, that they end up taking kids to the doctor and leaving early when a child gets sick at school. Is that true? One way to find out would be to go into personnel files and look at sick days, tardiness and hours worked.”

Another way to extend the study would be to distinguish between women with young children and those with children in, say, college. “If it’s really just the doctor and PTA meetings, then you shouldn’t find the same effect with older women,” Madrian said.

Whatever their rationale, the student raters appeared to penalize mothers for not being as committed to their careers. Their assumption seemed to be that, for working mothers, parenthood eats up time that otherwise would be devoted to their jobs.

Smokers: Less Efficient Learners?

The study on smokers vs. nonsmokers, by Nachum Sicherman, an economist at Columbia, and Lalith Munasinghe, an economist at Barnard, tries to explore the same problem — that is, how much effort workers expend on career development — in a different way. They suggest using smoking as a proxy for employees’ willingness to invest in their advancement and their ability to learn new skills. In their paper titled, “Wage Dynamics and Unobserved Heterogeneity: Time Preference or Learning Ability?” they argue that smokers might invest less and therefore learn less than nonsmokers.

That conclusion might be startling to some. After all, aside from taking the occasional cigarette break, smokers wouldn’t seem to differ much from other workers. In addition, many high achievers like to light up. California governor Arnold Schwarzenegger even has pitched a tent outside his state office building so he can puff cigars while working. (California bans smoking in government buildings.)

Peter Cappelli, a Wharton management professor and the main organizer of the conference, pointed out that the authors are employing a time-honored research technique. They are using something that can be observed — smoking — as a proxy for something that’s difficult to observe, at least at the macro level. “It’s a way of trying to get at people’s risk preferences and their willingness to think about the future,” he explained. “Smoking is so obviously not a future-oriented decision.” Cappelli also cited the existence of “interesting public-health research showing that people understand the risks of smoking but don’t care.” Meanwhile, a conference participant said that, according to independent research, 30% of Japanese are daily smokers. In Belgium, Norway and France, that figure is 29%. In the U.S., 18% of the population smokes.

Sicherman, a smoker himself, and Munasinghe argue that smokers may differ from other workers in key ways. Smokers, they say, do seem to value present enjoyment over future costs. They accept the long-term risk of diseases, such as lung cancer and emphysema, for a nicotine hit today. In an economist’s terms, they have a higher discount rate, which makes them less willing to make investments, including investments in their health. “Those who discount the future more heavily will clearly weigh their current wages relative to their future wages more heavily than those who discount the future less,” Sicherman and Munasinghe write.

In addition, the economists argue that smokers may be less efficient learners. Their smoking suggests that they haven’t figured out, despite overwhelming evidence, that their habit causes disease. “If efficient learners are also less likely to smoke because their higher learning ability leads them to better understand the negative effects of smoking, then it is possible that this unobserved dimension of learning ability could be the culprit behind the observed negative correlation between smoking and wage growth rates,” the authors write. 

More efficient learners, in contrast, might be more willing “to invest in more schooling as well as other forms of human capital, including job training,” Sicherman and Munasinghe say.

The two economists, therefore, designed a statistical model to test their hypotheses. Using wage and demographic data from the National Longitudinal Surveys of Youth, covering 1979 to 1994, they concluded that present orientation — or, to use their term, smokers’ greater discount rate — explained smokers’ lower wages while differences in learning ability didn’t. “Our findings raise the possibility that a variety of psychological and personality traits are likely to be more important than simple cognitive ability to process information in explaining differences in labor market outcomes across individuals,” they conclude.