Those gifts paid for a small staff and a gallery of random-motion machines, including a pendulum with a lighted crystal at the end; a giant, wall-mounted pachinko-like machine with a cascade of bouncing balls; and a variety of electronic boxes with digital number displays.

In one of PEAR’s standard experiments, the study participant would sit in front of an electronic box the size of a toaster oven, which flashed a random series of numbers just above and just below 100. Staff members instructed the person to simply “think high” or “think low” and watch the display. After thousands of repetitions  the equivalent of coin flips  the researchers looked for differences between the machine’s output and random chance.

Analyzing data from such trials, the PEAR team concluded that people could alter the behavior of these machines very slightly, changing about 2 or 3 flips out of 10,000. If the human mind could alter the behavior of such a machine, Dr. Jahn argued, then thought could bring about changes in many other areas of life  helping to heal disease, for instance, in oneself and others.

This kind of talk fascinated the public and attracted the curiosity of dozens of students, at Princeton and elsewhere. But it left most scientists cold. A physics Ph.D. and an electrical engineer joined Dr. Jahn’s project, but none of the university’s 700 or so professors did. Prominent research journals declined to accept papers from PEAR. One editor famously told Dr. Jahn that he would consider a paper “if you can telepathically communicate it to me.”

Brenda Dunne, a developmental psychologist, has managed the laboratory since it opened and has been a co-author of many of its study papers. “We submitted our data for review to very good journals,” Ms. Dunne said, “but no one would review it. We have been very open with our data. But how do you get peer review when you don’t have peers?”

Several expert panels examined PEAR’s methods over the years, looking for irregularities, but did not find sufficient reasons to interrupt the work. In the 1980s and 1990s, PEAR published more than 60 research reports, most appearing in the journal of the Society for Scientific Exploration, a group devoted to the study of topics outside the scientific mainstream. Dr. Jahn and Ms. Dunne are officers in the society.

News of the Princeton group’s experiments spread quickly worldwide, among people interested in paranormal phenomena, including telekinesis and what people call extrasensory perception. Notable figures from Europe and Asia stopped by. . Keith Jarrett, the jazz pianist, paid a visit. For a time, the philanthropist Laurance Rockefeller visited regularly and donated money for research.