: The National Park Service promotes the "Rule of Thumb" for viewing wildlife like elk; if you cannot completely cover the animal with your outstretched thumb, you are too close.
Clinical reports highlight specific thumb issues that may require professional covering or intervention in mature patients. mature thubs
In broader reports, "covering with the thumb" is used as a metaphorical or literal safety metric: : The National Park Service promotes the "Rule
: These devices act as a physical deterrent for adult thumb sucking, skin picking (dermatillomania), nail biting, or hair pulling (trichotillomania). skin picking (dermatillomania)