The problem at the time of making such a study is to determine the true cause of the thickening in the caliber of the hair. How can we be sure that the cause was not the pass of the time? People tend to believe that we are responsible for all changes that occur in our body. Nothing is further from the truth. One of the myths that circulate in my culture (and probably beyond here) is to think that if you pluck one of the first gray hairs that appear in your head, you will see 7 more. Any explanation is better than accepting the fact that this is a sign of aging.
In any case, every time you pluck a hair, you are resetting the cycle of the follicle. The follicle is affected because you are altering its natural course. Have you seen that sometimes a small drop of blood appears on the surface of the skin when you extract it to your hair? Well, somehow you're doing a tiny lesion in the wall of the follicle. This damage is not enough to stop production of the hair, but it is sufficient to stimulate blood circulation, and our skin sends help to repair the damage generated. This will cause the biostimulator effect and the hair acquires thick.
Anything that produces a mild injury, but repeated in hair-bearing skin, will produce a stimulation in the area surrounding the wound.
Many studies have demonstrated this phenomenon. And although they did not exist, the electrologist has ample evidence in his/her case file, with being just a little observer.