Ernest Ropiequet "Jack" Hilgard (1904 - 2001) was an American psychologist, professor at Stanford university, who became famous in the 1950s for his research on hypnosis, especially with regard to pain control. Along with André Muller Weitzenhoffer , Hilgard developed the Stanford Hypnotic Susceptibility Scales from the 1950s onwards.
Ernest Hilgard became convinced that we all have another being sharing our lives. Hilgard termed this entity the ‘‘hidden observer.’’ In one of his books, Hilgard described a classic test of how this hidden entity is part of our consciousness. Hilgard conceived of the "hidden observer" as that part of the mind which communicates with the hypnotist but is not available to consciousness. Relative to this theory, pain control under hypnosis would involve the inhibition of specific areas of the brain in connection with the dissociative effect of hypnosis.
One of Hilgard’s subjects made the following interesting statement about what she experienced, making particular reference to what she sensed was her higher self: The hidden observer is cognizant of everything that is going on. . . . The hidden observer sees more, he questions more, he’s aware of what is going on all of the time but getting in touch is totally unnecessary. . . . He’s like a guardian angel that guards you from doing anything that will mess you up. . . . The hidden observer is looking through the tunnel, and sees everything in the tunnel. . . . Unless someone tells me to get in touch with the hidden observer I’m not in contact. It’s just there.
This idea of the basic duality of human personality is culturally and historically almost universal. The ancient Chinese called these two independent consciousnesses hun and po, the ancient Egyptians the ka and the ba, and the ancient Greeks the Daemon and the Eidolon.