A study released today claims to have found evidence that, if specifically requested, God might heal those with impaired hearing and vision.

Candy Gunther Brown, an associate professor in the Department of Religious Studies at Indiana University Bloomington, led the study of “proximal intercessory prayer.” The study, published in the September issue of the Southern Medical Journal and titled “Study of the Therapeutic Effects of Proximal Intercessory Prayer (STEPP) on Auditory and Visual Impairments in Rural Mozambique,” measured improvements in vision and hearing in a rural area of the Southern African country.

The team used an audiometer and vision charts to evaluate 14 patients who reported impaired hearing and 11 who reported impaired vision, both before and after members of a local church prayed for their healing. Subjects reported a small but statistically significant improvement in hearing and vision following the prayers.

So is this proof of God’s existence, or that praying to a higher power bestows some benefit?

At first glance the study is interesting, but upon closer examination serious limitations become apparent. First, the sample size is tiny; with only 24 participants the results are very difficult to generalize to a larger population. Second, the measures studied by Brown and her colleagues were inherently subjective, and not objectively measured. Indeed, the authors admit that “auditory and visual impairments are…. not unaffected by psychosomatic factors.”

A double-blind study (that is, one in which neither the researchers nor the patients knew who was prayed for) would have been far more reliable. This would help control for the well-known placebo effect; it is not only possible but likely that those who receive personal, special attention from prayer groups and researchers might genuinely believe that they can see or hear better, at least temporarily—much in the way that a person who takes a placebo pill that they believe to be a pain reliever might experience less pain.

Furthermore, the study did not control for the pre-existing beliefs of the patients. According to the study, “subjects were recruited at Charismatic Protestant meetings… widely reputed among pentecostals globally as ‘specialists’ in praying for those with hearing and vision impairments.” That is, all the subjects used in the study not only firmly believed in the power of prayer, but that such prayer was especially helpful in treating eye and ear problems. The subjects could have easily been influenced by what scientists call “demand characteristics,” or patients telling the researchers (and those who prayed) what they think they want to hear. It would be interesting (and important) to know whether or not maladies in atheists, agnostics, and others who lack a pre-existing belief in the power of prayer would be improved.

It is worth noting that far better-designed studies have found that prayer is not effective. In 2006, researchers at six major medical centers, including Harvard and the Mayo Clinic, completed the largest prayer study to date. The research (“Study of the Therapeutic Effects of intercessory Prayer ‘STEP’ in cardiac bypass patients,” published in the American Heart Journal) was conducted over nearly a decade and led by Dr. Herbert Benson. It included 2,000 cardiac surgery patients who were randomly assigned to different prayer groups. Prayer had no beneficial effect on recovery time, death rate, or any other factors.

Brown and her colleagues did not address the mechanism by which the prayer was supposedly effective (how, exactly, the prayer helped), nor why a benevolent God would only help those who He is specifically asked to assist. Using the premises and definitions of “proximal intercessory prayer” described in this study, presumably a lone hiker in the wilderness suddenly struck unconscious and mortally wounded in a rock slide would be ignored by God if no one knew of his circumstances and offered prayers for him, while a man struck down by lightning in front of his family would get God’s immediate attention. Perhaps future research will explore this premise.