This here is my theory of Psychic power. I have no experience with Psychic powers, and thus I have nothing but a theory. If anyone has any insight on this subject, I would enjoy very much to read it. Too, if it is that someone can disprove this theory, though non-antidotal means, I would welcome it. Conversely, if anyone has proof that supports this theory, I too would welcome it.
Here is my theory:
Telekinetic power is the ability to direct energy from within a person to the outside world. Therefore, when one moves an object with their mind (as opposed to their body) they would use from themselves an amount of energy equal to the natural amount of energy excreted (when one moves something with their hands, excreta) times ten. In other words, if it takes one calorie to move a cup one meter to the left, it would require ten calories to move the same cup one meter left with telekinetic power.
I say this because of a basic biology principle. When energy is transferred, only ten percent is available to the object, or person, to whom the energy is transferred. This is because ninety percent of transferred energy is lost, bleed off as heat.
Keeping with this assumption, Psychokinetic powers are the same as Telekinetic, save that you dont draw the power from yourself, but from around you. Thus, to move a cup one meter to the left would not take ten calories, but one hundred calories total (drawing one hundred calories, where ninety-percent are lost, would then leave you with ten, allowing for the same math as is used in the above paragraph.)
Naturally, this raises the question of why everyone doesnt use Psychokinetic, if it takes from around you, and not from you yourself? An answer to this is two parts.
First, using any type of psionic ability takes focus, a deep sort of self-knowledge. Most people simply dont have the self-control, the mental discipline, needed to direct their energy with just their thoughts. (Thus we have Magick, the ability to direct energy into the world around you in such a way that it affects reality. Magick uses words, among other things, to give structure to your power, allowing you to have less self-discipline, though quite a lot is still needed.)
Second, using Psychokinetic power requires your body to act as a conduit for the energy being used. This weakens the overall constitution of your body, preventing you from achieving greater goals.