Object vertical and horizontal position depends on its sense of universe. Hi flyers make themselves aware of things below them because that is exactly where their danger comes from however, bottom flyers defend themselves of things above them because that is their deadly enemy position. Human, animals protect their fronts but, technically reactive of things behind them. If you touch a person behind, they are likely to touch any part of you in a way that will be faster than you had done them however, you touch a person from their front, they are likely to hurt you verbally. We are faster forward and slow backward. All also takes time thinking of things we should do often than things we do because thinking is a virtual and doing is practical. Virtual things reminds while practical things are actual. Front of our head is bare while behind our head is covered with hair. In general our back is stronger and can take more pain than our front body because our front body is softer and our behind is stronger.