Only 28 percent of American CEOs are women. To find out why such a gap exists, a study published this fall in Personnel Psychology analyzed more than 100 papers on leadership emergence published between 1957 and 2017. In the papers, samples of students or co-workers were asked to select group leaders or to rate one another on the extent to which they led a group. Some of the papers also measured group participation and personality traits such as assertiveness. As predicted, men emerged as leaders more often than women. But that gap varied depending on the length of interaction and other factors (graphic).
The data suggest that men were more likely overall to be chosen or rated as leaders, in part because they had more assertive personalities and thus spoke up more. Men and women were equally likely to emerge as leaders, however, when groups interacted for more than 20 minutes—possibly, the researchers write, because members relied less on gender stereotypes as they became better acquainted.