LOVELAND, Colo. — Using little more than a towel and a piece of cardboard, a 9-year-old girl conducted a “brilliant” study debunking therapeutic touch, an increasingly popular alternative treatment practiced by some 40,000 nurses and caregivers in the United States.

Along the way, Emily Rosa, now 11, apparently has become the youngest researcher to publish a scientific paper in the prestigious Journal of the American Medical Association. She co-wrote the final report — which appears today — with her parents and a physician who specializes in uncovering medical fraud.

In a test that started out as her fourth-grade science project, Emily recruited 21 practitioners of therapeutic touch and found that they could not reliably detect another person’s “energy field” after all, contrary to one of the practice’s central tenets.

“I think of me as a kid who did a simple science experiment,” said Emily, an avid Spice Girls fan and budding flamenco dancer who lives with her mother, a registered nurse, and father, a mathematician-inventor, in this semirural town north of Denver.

“Age is irrelevant,” the journal’s editor, Dr. George D. Lundberg, said of the investigator’s youth. “It’s the quality of the science that matters. ”

Given the new findings, Lundberg urged in an editorial that patients should “save their money and refuse to pay for this procedure until or unless additional honest experimentation demonstrates an actual effect.”

Proponents of therapeutic touch disputed the study’s importance, criticizing its premise and setup. They also complain that the study is hardly dispassionate, because Emily’s mother, Linda Rosa, a registered nurse, is an avowed critic who has spent years amassing evidence and lobbying against the procedure’s acceptance.

Practitioners claim to promote healing by holding or moving their hands a few inches above a patient’s body, which is said to realign “energy fields” disrupted by illness.

Professional organizations such as the National League for Nursing and the American Nurses’ Association have promoted therapeutic touch or energy healing, and some 80 hospitals in North America reportedly offer the treatment.

Scientific evidence supporting the practice or the theories behind it has been elusive, despite many articles over the years reporting successful cases.

Emily and her co-authors say she may have been able to overcome practitioners’ reluctance to subject themselves to testing “because the person conducting the test was a child who displayed no skepticism.”

She zeroed in on the central idea that practitioners can sense another person’s “energy field” with their own hands. Indeed, they have described patients’ energy variously as feeling cold, hot, sticky, tingling or throbbing, among other things.

In the study, each therapist sat across from Emily at a table, laying his or her arms out flat, palms up. A cardboard partition with cutout armholes placed over their forearms blocked their view of their hands and of Emily. A towel draped over their arms also prevented peeking.

The test consisted of Emily placing one of her hands a few inches above a therapist’s right or left hand, as determined by the flip of a coin. If the therapist could sense which hand better than 50 percent of the time, that would support the theory. Fourteen practitioners got 10 tries each, while seven got 20 tries.

Overall, the average correct score was 44 percent, which is less than what would be expected by chance alone. “They were correct about half the time — about what you’d expect from guessing,” Emily said. “Of course, they came up with excuses. One said the room was too cold. Another complained that the air conditioning blew the force field away.”

Cynthia Hutchinson, a therapeutic touch instructor in Boulder, Colo., with a doctorate in nursing science, voiced a suspicion of the AMA common to many practitioners of alternative medicine. It is “a political organization and many physicians who belong to it feel threatened by human aura therapy because it means their power and money are being taken away.”