In the early 1950s, 300 actors, writers and others suspected of being communists were blacklisted in Hollywood and excluded from the workforce. A recent study, coauthored by Professor Hayagreeva Rao of Stanford GSB, analyzes how social networks of the day resulted in hundreds of individuals whose names were not on the list being denied jobs.

Some 60 years later, lessons can still be drawn about how stigma may spread through relationships. For instance, proof of drug use by athletes with one team in a specific sport may result in advertisers pulling their support for the entire sport or from related sports. Companies accused of operating overseas sweatshops may see the taint spread to partners or suppliers despite upstanding labor practices.

During the Red Scare, artists not on the list drawn up by the House Committee on Un-American Activities saw their chances of finding employment drop by 13% if they previously had worked with someone named on the blacklist, even if they had worked with that person before the list existed.

For actors, the effect of working with a subsequently tainted writer was even greater than the effect of working with actors and other Hollywood professionals. Actors faced a 20% drop in employment if they had worked with writers who were later blacklisted.

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p>Elizabeth Pontikes, of the University of Chicago Booth School of Business, Giacomo Negro of Emory University, and Rao coauthored the study, which is published in the June issue of the American Sociological Review.

A higher profile did not necessarily offer shelter. The researchers said artists who appeared in a top 10 box-office film were 16% less likely to find a job after a co-worker was blacklisted, compared to a smaller 10% drop for similar artists in less successful films. Oscar winners, however, were partly shielded. The odds of an Oscar-winning artist finding a job after a co-worker was blacklisted were reduced by 9%.