Keith DaSilva, age 9, of Coventry, R. I., for his question:

HOW DOES HYPNOSIS WORK?

Hypnosis is an artificially induced passive state in which an individual will respond to suggestions and commands that do not conflict with his wishes. No one knows exactly how it works, but the nervous systems of susceptible subjects do indeed respond.

Medicine and psychiatry find hypnosis a useful tool when used by trained physicians.

There remains some prejudice against hypnosis, but it has had enough success to more than prove its value in the medical arts. It has been used effectively in studying childhood influences through suggesting age regression, in recalling significant memories and in treating organic symptoms caused by mental conflicts.