Psychological Safety

Definitions

A shared belief within a team that members can speak up, admit mistakes, ask naive questions, and disagree without being punished or humiliated. The concept was developed by Amy Edmondson, whose hospital research produced a striking initial result: better teams appeared to make more errors, until she realised they were reporting more of them. Google's Project Aristotle later identified psychological safety as the strongest predictor of team effectiveness among the factors it studied. In engineering practice it shows up as blameless postmortems, willingness to flag a risky deploy, and juniors questioning senior decisions. It is routinely confused with niceness or an absence of conflict; Edmondson's account is close to the opposite, describing a condition that makes candid disagreement possible rather than one that suppresses it.
In plain English: A team culture where people feel safe to admit mistakes and ask questions without fear of being judged or punished.
Example: "In a psychologically safe team, a junior dev can say 'I don't understand this architecture' without being judged — and the team gets better documentation as a result."