One idea, readable on a phone. Test face against no face.

One idea readable at phone size, two or three elements at most. Real, strong emotion helps; fake shock doesn't. Keep thumbnail text short and calm. Within a channel, face size and colour pop did roughly nothing, so test face against no face.
P Evidence: promising. Good studies, but small or few. Use it and keep checking.
E Evidence: built from practice. What works for coaches and practitioners. Labelled that way.
Koh & Cui 2022 · Cui et al. 2024 · an industry study of 1.25 M videos.
Not medical, legal or financial advice.
In The Ecosystem every framework comes with a daily action, a room that checks in, and the full library.