In one of Dr. Griffiths’s first studies, involving 36 people with no serious physical or emotional problems, he and colleagues found that psilocybin could induce what the experimental subjects described as a profound spiritual experience with lasting positive effects for most of them. None had had any previous experience with hallucinogens, and none were even sure what drug was being administered. To make the experiment double-blind, neither the subjects nor the two experts monitoring them knew whether the subjects were receiving a placebo, psilocybin or another drug like Ritalin, nicotine, caffeine or an amphetamine. Although veterans of the ’60s psychedelic culture may have a hard time believing it, Dr. Griffiths said that even the monitors sometimes could not tell from the reactions whether the person had taken psilocybin or Ritalin. The monitors sometimes had to console people through periods of anxiety, Dr. Griffiths said, but these were generally short-lived, and none of the people reported any serious negative effects. In a survey conducted two months later, the people who received psilocybin reported significantly more improvements in their general feelings and behavior than did the members of the control group.