A small child works out how to feel about itself by looking at its parents' faces. If that face was missing, or busy, the looking does not stop, it just moves on to teachers, coaches, friends and strangers.

What the research says

In a small waitlist controlled trial, 38 highly self-critical adults were randomly assigned to a loving-kindness meditation programme or a waiting list, and self-criticism fell while self-compassion rose. So a deliberately practised inward warmth can shift things, even in people who are hard on themselves. Thirty-eight people is a very small trial, and the comparison was a waiting list rather than another active approach.

Strength of evidence: one line of research. A single study, or a theoretical account.