Sense psionics

Sense Psionics is a type of psionic power, able to be utilized by both terrans and zerg.

Terrans
Some terran psychics are able to utilize sense psionics to identify other psychics and the aftermath of psionic activity. A ghost, MacGregor Golding, was able to identify an unregistered civilian telepath just by looking at her. In weaker psychics, such as Wranglers, this ability manifests as a headache in the presence of another psychic (or the remnants of psychic activity), with an intensity matched by the power of the psychic being detected. The ability can be honed through equipment and (sometimes) other esoteric methods, enabling a psychic to track another one at a distance.

Ghosts routinely use this ability to detect sources of energy. Ghosts generate alpha waves when using psionic abilities (such as their partially psi-generated cloaking field), which can be detected by other ghosts. Sarah Kerrigan used this ability to detect the presence of another ghost in a battle, but could not determine his exact location without technological assistance.

Zerg
Zerg are sensitive to psionics and can sense psi emitters from a great distance, even across worlds.

The zerg attraction to psionics is poorly understood by the general civilian populace, and the impact that psychic dampeners have on this attraction is a point of dispute.