Timothy F. Leary, the former psychology professor who was once nationally famous as an advocate of psychedelic drugs, said that he had the informed consent of a group of Massachusetts prisoners to whom he gave a hallucinogenic drug in an experiment 30 years ago.

"My God, whenever you do any kind of drug research . . . you have to give the patient every kind of {information}," said Leary, who was a Harvard University lecturer when he and others administered the drug psilocybin to inmates at Concord State Prison in 1961-62. The experiment was intended to see if the drug, which has properties similar to LSD, would reduce inmates' criminal behavior. "This was not a researcher from Harvard who went in, dumped a lot of drugs on people and walked away," he said.

Reached at his home in Beverly Hills, Calif., Leary, 73, made the remarks in response to an article in yesterday's Boston Globe, which quoted former state prison officials as saying that the prisoners involved might not have been fully told of the drug's effects, including flashbacks. Leary discussed the prison experiment, as well as other experiments using student volunteers, in autobiographies in 1967 and 1982.

The article noted recent disclosures that government and academic researchers conducted radiation experiments on hundreds of people in the 1940s and 1950s, some apparently without their knowledge.

Richard Doblin, a doctoral student at Harvard's Kennedy School of Government, said he has studied prison records of the experiment, which indicate that the 34 inmates involved "definitely knew" they were going to receive "a psychoactive drug." He said the records show the inmates received between one and four doses of the drug during the experiment.

Doblin said he received a letter from one of the participants, who said that he was aware he was taking a mind-altering drug. "I haven't talked to any of the others, but from the written documents, it describes how they were informed about what was going on," Doblin said. He added: "I think any kind of claim that Leary acted as unethically as people who gave radiation {to unknowing subjects} is unwarranted."

After Harvard fired Leary in 1963, amid controversy over his use of student volunteers in LSD experiments, his career took many colorful turns. He founded the League for Spiritual Discovery to promote the "religious" use of LSD and, in 1969, had a marijuana conviction overturned by the Supreme Court. He was later convicted again on marijuana charges, escaped to Algeria, then returned and served three years in prison.

Asked to describe himself now, Leary said he has "always been a dissident philosopher from the school of Socrates."