Affidavit of Dr. Jay Katz

Dr. Jay Katz, Professor (Adjunct) of Law and Psychiatry at Yale University and Attending Psychiatrist at the Yale New Haven Medical Center, gave a sworn affidavit to the Clay Shaw defense team on the dangers of testimony obtained under hypnosis.
In recent years, I have become especially interested in the study of the relationship of hypnosis and hypnotizability to credibility. I recently conducted an experiment demonstrating how a fiction can be implanted into a normal person via hypnosis. Even out of the trance state, he believed it with the conviction of a true fact . . . . Upon the basis of my training, study and experience I conclude the following: Hypnosis is a state of intense and sensitive interpersonal relatedness characterized by nonrational submission and relative abandonment of executive (ego) control. Heightened suggestibility (i.e., inclination to believe what others desire him to believe) is perhaps the most salient characteristic of the state of hypnosis. . . . There is a close correlation between a subject's suggestibility in a normal, non-hypnotic state and his hypnotizability. Persons who are not hypnotizable tend to be the least suggestible element of the population. Persons who may be induced in a deep trance tend to be among the most suggestible. . . . False ideas and beliefs can be implanted upon the mind of a subject who is in a trance without any intent on the part of the questioner to implant such beliefs, if the subject thinks that the examiner, or hypnotizer desires him to entertain such beliefs or if such beliefs seem to him to be necessary to support other beliefs or to please the hypnotizer or whomever he represents. The ease with which such implantation can occur varies with the hypnotizability of the subject. . . . Induction of a trance may alter the relationship between the subject and the hypnotizer so that the subject is more open to suggestion by the hypnotizer (or one whom the subject identifies with him) in subsequent interrogations outside the trance state. . . . Once a subject is hypnotized he may continue to be in a trance for months thereafter, although he may not appear to an untrained observer to be in a trance. The subject may also have a previous trance reactivated months after he has, according to all normal criteria, come completely out of the previous trance. Compliance with a so-called "post-hypnotic suggestion" is an example of such trance reactivation. It may occur long after the initial trance and will often not be apparent to the observer. (James Kirkwood, American Grotesque, pp. 152-153).

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