A psychiatrist noticed his depressed patients' thoughts were simply inaccurate

In the early 1960s, Aaron Beck kept hearing depressed patients voice automatic thoughts — 'I'm worthless,' 'this will fail' — that didn't hold up against the evidence. Rather than dig into their unconscious, he taught them to catch and test these distortions directly. The approach, cognitive behavioral therapy, is now among the most rigorously evidence-backed treatments in psychiatry.

— Aaron T. Beck, Cognitive behavioral therapy — Developed from the early 1960s onward