In 3rd and 3.5 editions, Psions are mechanically similar to Sorcerers; however, like Wizards, they can (and, unlike Wizards, must) specialize in one of the psionic disciplines. In 3rd edition the various disciplines were each linked to a statistic; for instance, clairsentience is linked to Wisdom, and Psions who specialize in it are known as Seers. This was changed in 3.5 so that all disciplines are linked to the Intelligence statistic. Psion is the favored class of the elan race (found in the "Expanded Psionics Handbook"). In both 3rd and 3.5 editions, Psions expend power points to activate their psionic powers. In 3.5 edition, psionic powers can be augmented by spending additional power points on them.