The open palms are usually seen as a gesture of openness.
I have answered a related question, and I will use the same source as I used there, namely an interesting interview from Euro News with two communication experts, Stevens and prof. Beattie.
They claim that the open-palms gesture (Fig. 1) is one of all-inclusiveness and ...
This question is far too broad for this forum. In fact, entire books have been written on this topic. An extensive review by Wohlrab, Stahl, & Kappeler (2006) "Motivations for getting tattooed and pierced" divides the literature into 10 broad categories of reasons:
Beauty, art and fashion
Two major terms:
of pitch height (lower/higher):
Some papers argue that even time has strong spatial ...
Many individual papers report non-reproducible findings. I would advise you to look for review papers and meta-analysis studies to get the bigger picture. If not available, you can consider to set up a literature study yourself.
Nature puts it down neatly (emphasis mine):
Science moves forward by corroboration – when ...