Hire a quarter from outside

Ronald Burt of the University of Chicago studied managers at a large electronics company and found that those who connected otherwise separate groups produced better ideas, according to his 2004 paper in the American Journal of Sociology. People inside one group tend to share information and assumptions, so ideas circulate within the same circle. Someone who has worked in another industry brings different problem-solving habits across the gap. Burt called the gaps between such groups structural holes.

Michael Lombardo and Robert Eichinger, researchers at the Center for Creative Leadership, introduced the term in 2000. They defined it as the willingness and ability to learn from experience and apply it to new situations. Their work started from the observation that past success in one role did not reliably predict success in a different one. Consultants and companies have used the concept in executive selection since.

Amy Edmondson of Harvard Business School studied hospital nursing teams in the 1990s and found that the better-led teams reported more errors than the weaker ones. They reported more because members felt safe speaking up. She called that shared belief psychological safety and published the finding in 1999. Google's internal Project Aristotle later ranked it as the most important of five traits shared by its highest-performing teams.