Mental Radio was written by the American author Upton Sinclair. This book documents Sinclair's test of psychic abilities of Mary Craig Sinclair, his second wife, while she was in a state of profound depression with a heightened interest in the occult. She attempted to duplicate 290 pictures which were drawn by her brother. Sinclair claimed Mary successfully duplicated 65 of them, with 155 "partial successes" and 70 failures. This edition included a preface written by Albert Einstein who admired the book and praised Sinclair's writing abilities. The psychical researcher Walter Franklin Prince conducted an independent analysis of the results. He believed that telepathy had been demonstrated in Sinclair's data. Prince's analysis was published as "The Sinclair Experiments for Telepathy" in Part I of Bulletin XVI of the Boston Society for Psychical Research and was included in the addendum for the book.