By the Numbers30 Scientific American April 2000

all-new airliner will fit in with existingairport infrastructures. Or the simulatorcan let controllers test new software andhardware. And, Dorighi adds, “somethingwe plan to do is integrate a noise modelthat will allow us to predict a footprint ofnoise.” Looking even further ahead, NASAplans to use the room to develop 360-de-gree immersive mission-control rooms forrobotic explorations of other planets.

The virtual-tower concept evolved froma prior project called the Surface Move-

ment Advisor, a software tool that Amesbegan developing in 1994 to reduce thetime airliners spend on the ground. At At-lanta’s Hartsfield International Airport in1997, the Advisor chopped one minute offthe average taxi time per airliner, savingan estimated $20 million in fuel. Future-Flight Central was developed as an opera-tional test bed for the Advisor. Dedicatedlast December, the virtual-reality controltower has recently signed its first two cus-tomers. Clients will be charged at cost,

Dorighi indicates, which could range from$50,000 on up.

Still, she insists, the facility will takepains to keep out of local free-for-alls likethe one brewing in San Francisco. “Basi-cally we’re a neutral party providing thescience,” she observes. “We’ll give themthe measurements. But NASA is not takingsides.” —Phil Scott

PHIL SCOTT, based in New York City,specializes in aviation issues.

Of the 21 million professionaljobs in the U.S., women hold53 percent, but most of theseare in fields that generally pay

only moderately well, such as publicschool teaching and nursing. Of the eightmillion or so jobs in the better-payingprofessions—those with an average com-pensation of more than $40,000 in1998—women hold only 28 percent. Al-most all these better-paying jobs are inthe six professions shown in the chart.

Overall, women’s share of professionaljobs appears to have stabilized, but theirshare of jobs in law and medicine is likelyto continue rising as an increasing pro-portion of degrees in these fields go towomen. In math and computer science,the proportion of women practitionersdeclined in the 1990s, although the num-ber of women in this rapidly expandingfield actually rose. According to RuzenaBajcsy of the National Science Founda-tion, women’s declining share of comput-er-science jobs reflects, in part, a hugesurge of men into the profession in recentyears as salaries rose markedly. She sug-gests that the increasing emphasis in thecomputer business on long hours, whichconflict with family responsibilities, mayhave caused many women to go into oth-er work. Another contributor to low fe-male presence in computer jobs is the de-clining number of women receiving de-grees in computer science beginning inthe 1980s, a trend that was only reversedin 1997, when the number of femalegraduates rose moderately.

Women’s share of jobs in the naturalsciences and on college and university fac-ulties leveled off in the late 1990s, despite

an increase in the proportion of womenreceiving academic degrees in these fieldsin recent years. The U.S. Bureau of LaborStatistics predicts that total employment—male and female—in the professions willrise 27 percent between 1998 and 2008,with each of the six professions on thechart enjoying double-digit growth.

Women in the six professions averagelower pay than men because they tend towork fewer hours and are in less financial-ly rewarding positions. They are, for ex-ample, underrepresented in some high-paying medical specialties, such as cardi-ology and orthopedic surgery, and theyare less apt to be partners in the biggestand most prestigious law firms.

But there appears to be a more funda-mental reason why women make less: thewidespread perception that men are bettersuited for important work. In the formula-tion of Virginia Valian, a psychologist at

Hunter College, both males and females,from early childhood, develop what sheterms “gender schemas,” or sets of typical-ly subconscious expectations about theproper role of the sexes, including the pro-fessional competence of men and women.“We expect men to do well,” she says,“and see their behavior in the rosy light ofour positive expectations. Conversely, weexpect women to do less and judge theiractual performance in the darker light ofour negative expectations.” Once peoplehold a gender schema, they tend to keep itin the face of discrepant evidence.

According to Valian’s theory, negativejudgments induced by a gender schemamay be small, but their cumulative effectover the years results in substantially lessprogress by women, even when their cre-dentials and performance are equal tothose of men. Thus, women lawyers startout at the same salary as male colleagues,but after several years they are making lessand are less likely to become partners. Be-cause of gender schemas regarding the roleof the sexes in the home, household tasksfall mostly to women, who may then bepenalized if they work fewer hours thanmen in order to do housework. But in situ-ations where it is possible to juggle workand family obligations successfully, as inacademia, women still make less. That’s be-cause, Valian believes, they are judged inthe light of biased gender schemas. Thisbias occurs despite evidence that, she ar-gues, women’s output is superior to that ofmale colleagues: on a per-article basis, arti-cles by women are cited more frequently,although overall, men average more cita-tions, because they publish more fre-quently. —Rodger Doyle (rdoyle2@aol.com)

Women and the Professions

E M P L O Y M E N T _ G E N D E R D I S P A R I T Y

By

t

he

N

um

be

rs

ROD

GER

DO

YLE

Engineers (82)

All Professional Specialties (76)

Total All Civilian Jobs (76)

College and University Teachers (77)

Computer, Math Scientists (87)

Natural Scientists (81)

Physicians (77)

Lawyers (70)C

ivili

an J

obs

Fille

d b

y W

omen

in th

e U

.S. (

per

cent

)

60

50

40

30

20

10

01950 1960 1970 1980 1990 2000

SOURCE: U.S. Bureau of the Census and Bureau of Labor Statistics. Figures in parentheses indicate women's earnings as a percent of men's earnings in 1998. The trend lines show decennial census data for 1950–1980 and five-year moving averages thereafter.

Copyright 2000 Scientific American, Inc.