Doctors like to feel they have an important role to fulfil in society - and this was especially the case in the former East Germany where many were spies, telling tales on their patients.
It's been estimated that one in 20 doctors was a spy, working for Stasi, the East German secret police.
Recruitment among doctors was particularly high because they belonged to "a reactionary class and were thought to be especially interested in escaping to West Germany," said Francesca Weil, author of the study.
But doctors who were interviewed for the study said their main motivation was career advancement or money. So, not so different from their colleagues in the West, after all.
(Source: British Medical Journal, 2007; 335; 1119).