I think kissing your fingers is an interesting technique and probably a very good one for a young child. I'm noticing that I feel resistant to doing it for myself. I have been biting my nails since I stopped sucking my thumb way back when, so for about 45+ years.
I haven't really bothered trying to stop very often as it doesn't seem a high priority of mine. I don't bite them too badly, however I sometimes do rip my skin until it is very red and that does bother me. I would like to stop nail biting at some point. And I do know what will help me do it as I've had the experience of not biting my nails for about 3 weeks- twice- without trying to not bite them!
The first time was at an Ayurvedic healing/cooking retreat. We were set up to eat in silence, seated on the floor, 3 times a day. I decided to take this very seriously and began to eat very consciously and slowly and to feel the food land in my belly after chewing it very thoroughly, and putting my full attention on the chewing. I was even eating with my eyes closed. It was a very relaxing experience. I have a history of binge eating and was an exercise bulimic through my teens and twenties. So, the nail biting has always seemed related to managing low level anxiety.
By the end of the 10 days of this retreat, I was eating much much less and being satiated much much longer. It was fascinating. And when I left that environment, which was in the Blue Ridge Mountains near Asheville, North Carolina, I found myself not interested in biting my nails for at least 3 weeks! It was incredible! And I wasn't sure why. I wondered if it was the healthy food we ate, the cleansing and ayurvedic treatments I had done before going on the retreat etc...
That was about 6 to 7 years ago. Then last year I was reading a whole book about the benefits of eating slowly by an eating psychologist, The Slow Down Diet. Marc David explains really well why eating slowly can help you lose weight and it made total sense to me as I had experienced it at the retreat as I didn't need to eat more. So, I decided to try it again and managed to do it for about a week, almost all of my meals. I have to say it is very challenging to do,for me. I will take a lot of time preparing my food, but eating it slowly while doing nothing else is very challenging. It definitely brings up a lot of feeling that I am not able to manage without rushing through the food or doing another activity at the same time. But the inspiration of the book got my momentum going and sure enough I managed to pull it off for about a week.
And lo and behold, the desire to bite my nails completely went away for about 3 weeks! I could not believe it! So, based on Marc David's book, what I understood from this is that because I was digesting my food better, from eating slowly, which he totally explains scientifically, I was getting minerals, calcium, i'm guessing, that I normally don't get from the way I eat my food. So, when i don't get those minerals, I crave them and get some of them from biting my nails. A naturopath once told me that it was a mineral deficiency that was behind nail biting.
I think that is one part of the story. The other part is the underlying anxiety. The fact that it is so hard to sit with myself and eat and chew slowly and just be with myself is a clue. And I use food the way I use nail biting to take the edge off of my low level anxiety. I do feel I could initiate sitting with the feelings more and not indulging my nail biting. But I would have to really commit to that and then I might even consider kissing my fingers!
Thank you for writing about this issue as I've never read anything about it, though there probably is more out there. I appreciate your interest in this and I'm considering taking it more seriously and going to my next level of growth by addressing it in myself.