In 2016 Google described what it had learned from Project Aristotle, a study of more than 100 of its own teams. It called psychological safety “the most important factor to building a successful team.”
Amy Edmondson of Harvard Business School studied the idea. Her 1999 study found that psychological safety improved the performance of teams. One account puts the test into a single question: “Did you feel like you could ask what the goal was without the risk of sounding like you’re the only one out of the loop?”