The "psychic powers" stance is a crucial part of using mental powers. You need a look of intense concentration on your face, and a hand extended out towards whatever it is that you're trying to influence or control. Some visible muscle tremors are a nice addition.

If PCs fail to adopt this pose when using psychic abilities, feel perfectly free and justified in giving them a skill penalty!

Transcript

Yoda: Everything has a name. And an incredibly detailed back-story. Even the land, and the ship.
{Luke levitates while Yoda pushes down, the ship bubbles up a bit, but falls}
[SFX]: bubble...
[SFX]: bubble...
[SFX]: gurgle...
[SFX]: sink
Yoda: I wim! I wim! Ah ha ha ha!!
Luke: I see lessons in humility are a big part of this training.