The origin of Psychological Safety is somewhat unclear depending on the source, but according to PhD Howard B. Espin Psychological Safety was first introduced in the 1960’s by “pioneering organisational scholars”. Others say that Psychological Safety was introduced to the organisational sciences in 1965 by Shein and Bennis. However, in 1990 Dr. William Kahn, an organisational psychologist at Boston University, highlighted the concept and coined the new related term “employee engagement”. Kahn defined Psychological Safety as “feeling able to show and employ oneself without fear of negative consequences to self-image, status or career”.
In 1999 Professor Amy Edmondson published “Psychological Safety and Learning Behaviour in Work Teams” in the American magazine Administrative Science Quarterly. Her work amplified Kahn’s original definition. “A shared belief by members of a team that the team is safe for interpersonal risk-taking”. More specifically, she described “team climate characterised by interpersonal trust and mutual respect in which people are comfortable being themselves”.
But Psychological Safety was still not a big thing as late as 2014 when Professor Amy Edmondson published her review of Organisational Psychology and Organisational Behaviour. This review contextualises the concept of Psychological Safety and frames its importance for anyone collaborating with teams. This review was later followed up in a series of publications by her, which proved new benchmarks for Psychological Safety practitioners globally. But still nothing really happened until a report from Google was published, which revealed that the most important for team performance was Psychological Safety. This “Aristotle report”- where Google researched what made a team effective – was the icebreaker for Psychological Safety, and since then everyone talks about it, but few walk it.
 Hybrid Teams & Psychological Safety: https://www.linkedin.com/pulse/hybrid-teams-psychological-safety-howard-b-esbin-phd/
Psychological Safety: The History, Renaissance, and Future of an Interpersonal Construct: https://www.annualreviews.org/doi/abs/10.1146/annurev-orgpsych-031413-091305
 Google’s Project Aristotle: https://rework.withgoogle.com/print/guides/5721312655835136/