PHILADELPHIA — A half century later, Charlie Dyer still vividly remembers the day he was picked to join the “Fernald Science Club.”

It was 1954 and at 14, he had already spent nearly half his life in a succession of Massachusetts institutions that unflinchingly labeled kids like him “morons.” But his new place, the Fernald State School in Waltham, seemed like it might be different.

“They picked some of the oldest guys and asked us if we wanted to be in this club,” Dyer, 72, said in an interview from his home in Watertown, Mass. “We all got together and decided, why not? We’ll get time off the grounds.”

The boys were promised presents, outings to the seashore, trips to Fenway Park and extra helpings of oatmeal.

“It was like Christmas,” Dyer recalled. “Red Sox games, parties. I got a Mickey Mouse watch that I still have.”

It took decades before Dyer learned that he and the boys he still considers brothers were little more than guinea pigs. A state task force in 1994 found Massachusetts Institute of Technology scientists fed the unwitting boys radioactive oatmeal and milk for a Quaker Oats nutrition study.

His story is one of many told in a new book, “Against Their Will,” the result of five years of gathering data from medical and university libraries and archives, medical journals and records from many of the now-shuttered state hospitals and orphanages where experiments were conducted. “We thought something wasn’t right, but we didn’t know,” Dyer said. “They were using the kids who they were supposed to be helping.”

The authors interviewed nearly a dozen former test subjects, along with relatives of test subjects, medical researchers and historians.

“These are throwaway, unwanted, damaged people,” said Allen Hornblum, one of the book’s authors. “You had the best and the brightest minds doing this stuff, doing it very cavalierly and doing it exclusively to the most vulnerable.”

While researching his 1998 book “Acres of Skin” about medical experiments on inmates in Holmesburg Prison in Philadelphia, Hornblum came across documentation about similar experiments conducted on children and even infants.

Thousands of children warehoused in overcrowded orphanages and facilities for “feebleminded” children underwent spinal taps, lobotomies and electric shock. They were also exposed to viruses, radioactive and hazardous chemicals and given psychotropic drugs.

“I think people are going to be shocked,” Hornblum said. “These aren’t inmates … these are children who are having these things done to them.”

Dyer, a retired truck driver, makes ends meet with yard sales and odd jobs.

He and about 30 former “Fernald Science Club” boys filed a class-action lawsuit that settled out of court in 1998; Dyer says they ended up with around $30,000 apiece.