Psi Strength is a measure of the soldier's innate ability to defend against psionic attacks - and to execute them.
New recruits will always begin with a value between 0 and 100 (inclusive). Your soldier's Psi Strength will not be revealed until his or her first month of Psi Lab training is complete.
Prior to gaining Psi technology, if you have soldiers who are consistently panicked or mind controlled by aliens, it's a very good bet that they have low Psi Strength (below 60). (Aliens 'peek' and know who's low.) Don't strip such soldiers of their weapons and use them as scouts or cannon fodder, just fire them and get new soldiers. After one month of Psi training you know who is going to stay and who is going to be sacked.
As a consolation prize, soldiers who have panicked many times are liable to see their Bravery increase.
Psi Strength cannot be increased. It remains constant throughout the game.
|X-Com: Enemy Unknown/UFO Defense|
|Soldiers:||Time Units • Energy (Stamina) • Health • Bravery • Reactions • Firing Accuracy • Throwing Accuracy|
|Strength • Psionic Strength • Psionic Skill • Melee Accuracy • Stun • Morale • Rank • Fatal Wounds|