Self-help authors have sold millions of books touting the power of positive thinking. But negative thinking can have power, too, according to prizewinning author Stephen Hawley Martin in his new book, "A Witch in the Family," about the Salem witch trials. What it comes down to is belief "What it comes down to is belief," Martin said. "Belief is extremely potent. For example, the effectiveness of placebos has been demonstrated time and again in double-blind scientific tests. A report that came out four years ago says that after thousands of studies, hundreds of millions of prescriptions and tens of billions of dollars in sales, sugar pills are as effective at treating depression as antidepressants such as Prozac, Paxil and Zoloft. What's more, placebos bring about profound changes in the same areas of the brain these medicines are said to affect — according to this research. For anyone who may have thought otherwise, this proves beyond doubt that thoughts and beliefs can and do produce physical changes in our bodies." The same research reports that placebos often outperform the medicines they're up against. For example, in a trial conducted in April, 2002, comparing the herbal remedy St. John's wort to Zoloft, St. John's wort fully cured 24 percent of the depressed people who received it. Zoloft cured 25 percent. But the placebo fully cured 32 percent. "Taking what one believes to be real medicine sets up the expectation of results," Martin said, "and what a person believes will happen usually does happen. It's been confirmed, for example, that in cultures where belief exists in voodoo or magic, people will actually die after being cursed by a shaman. Such a curse has no power on an outsider who doesn't believe." Martin said he believes belief played a role in the Salem witch hysteria. He thinks the people who accused others of witchcraft truly believed they had been bewitched. So did everyone else involved. Even the people who were accused of being witches thought so –– although, if they were innocent, they may have thought someone else besides them was responsible. "I once saw an experiment concerning belief conducted before the television cameras of the Discovery Cable TV Network," Martin said. "In this case, two subjects participated in the same ESP experiment in the same laboratory using the same equipment. Great pains were taken to keep everything identical except for one thing. One subject believed ESP worked, and the other did not. The researcher who believed in ESP had a statistically significant number of correct hits, meaning the experiment was successful. But the number of correct hits by the skeptical researcher fell within parameters that could be accounted for by chance. Belief made the difference. Each researcher got the result he expected." A great deal of anecdotal evidence supports this finding. Researchers into the paranormal report that even the presence of someone who flatly does not believe can derail such an experiment. Belief, it seems, may be a requisite for at least some paranormal phenomena to happen. "Perhaps this is the reason non believers rarely experience anything that would lead them to doubt their position as skeptics," Martin said. Martin has won several national awards and prizes for his novels. The full title of his new book, which was published by The Oaklea Press, is "A Witch in the Family: An Award-Winning Author Investigates His Ancestor’s Trial and Execution." It presents a shocking but plausible new theory, based on the idea that belief has power, of what was behind the witch hysteria in Massachusetts.