Psi Lab (EU2012)
The Psionic Lab will allow you to test your soldiers for psionic powers. You may test up till 3 soldiers at a time, upon which they will be unable to join a mission during 10 day testing time.
The chances for getting a psionically gifted soldier seems to be random, but with a higher chance the better willpower the soldier has. Because of this, the current assumption is that a Colonel that started out with 52 psionic powers and ranked up while the [Iron Will] was active (with the maximum 12 Will increase per new rank) has the best chance of getting the gift.
A soldier with 50 willpower has less than 1% chance of being gifted. 
Using Save and Load, it was found that the chance of being gifted is calculated immediately when the soldier is put in the Psi Lab. This means each time the same soldier is removed and re-added to the training tab, he/she would have a recalculated chance of being gifted. This is best done when you have ten days of uninterrupted peace. It can be done while status and mission notices appear, but you'll have to ignore them each time (and if you have 7 on the Doom Tracker, and a Terror Mission pops up...). It is reccomended to use multiple save files if doing so.
To manipulate this: Gifted status is calculated not also on Will scores, but also with whom else are they submitted with, and in which slot when placed. In short: place your 3 soldiers in. Complete the testing, make note of who passes. Reload, take out and resubmit only those who do not pass (if it shifts the slot of those who will pass, do not worry: this does not de-gift them), and repeat as neccecary. If two or all 3 fail, you may find it helps the odds to put a different soldier in as a "placebo", put your desired soldier in, and take out the placebo.
With Second Wave Options Not Created Equal & Hidden Potential, and the OTS's Iron Will upgrade, those who you absolutley should manipulate to guarantee Gifted status are those with Will/Aim scores of both +70/+80, though those with scores of about 65/75 is a good median, and will suffice to fill out a Psi Squadron.
|XCOM: Enemy Unknown (2012): Base Facilities|
|Headquarters:||Mission Control • Hangar • Engineering • Research • Barracks • Situation Room|