Pehr Granqvist, a psychologist at Uppsala University, led a team that set out to test Persinger's God Helmet findings under conditions the original experiments lacked: a genuine double blind, in which neither the participant nor the experimenter running the session knew whether the magnetic field equipment was actually switched on. The 2005 study used equipment modeled on Persinger's own apparatus and measured the same kinds of reported experience, sensed presence, unusual bodily sensations and mood shifts, across sessions with the field present and sessions where it was not.
The result was a clean null: participants reported similar experiences whether or not the magnetic field was active, and the strongest predictor of who reported an unusual experience was not exposure to the field but a personality measure of suggestibility, how readily a person responds to expectation and suggestion in an experimental setting.