Unique to EarthBound and Mother 3 is that playable characters' psychic points are represented by a rolling meter similar to an odometer. This means that PP used by an ability will not immediately be diminished. However this very rarely proves to be either advantageous or disadvantageous to the player, unlike with hit points, as even moves that drain large amounts of PP like PSI Rockin Ω usually have animations long enough that the PP meter has finished rolling by the time the attack hits.
Concentration is needed for an enemy or player character to use a PSI ability. A few rare enemies in EarthBound (such as the Wetnosaur or the Mad Duck) can use an attack that can disrupt one playable character's concentration, making the PP-meter turn into an X. The character will be unable to use PSI until concentration is regained.
Some enemies also suffer from poor concentration, such as the Mr. Molecule enemy, making their PSI moves fail randomly.