Review by Sally Paddock, 2008
Granqvist, Pehr; Fredrikson, M.; Unge, P.; Hagenfeldt, A.; Valind, S.; Larhammar, D.; et al. 2005. “Sensed presence and mystical experiences are predicted by suggestibility, not by the application of transcranial weak complex magnetic fields.” Neuroscience Letter 379/1: 1-6
Persinger, Michael A.; Koren, S.A. 2005. “A Response to Granqvist et al. ‘Sensed presence and mystical experiences are predicted by suggestibility, not by the application of transcranial weak magnetic fields’.” Neuroscience Letter 380/3: 346-347.
Granqvist, Pehr. 2005. “Reply to ‘A response to Granqvist et al. “Sensed presence and mystical experiences are predicted by suggestibility, not by the application of transcranial weak magnetic fields”’.” Neuroscience Letter 380/3: 348-350.
For anyone who dismisses science journals and statistical explanations of laboratory experiments as reading material fit only for the cage-bound bibliographic research of bleary-eyed doctoral candidates, the research and correspondence between Pehr Granqvist and Michael Persinger is anything but another statistical analysis in a shelved science journal! Conducting follow-up research on Persinger’s dramatically popular studies of temporal-lobe stimulation and religious experience, Granqvist’s study initially aspired to achieving similar results so that PET scans could then study blood flow changes from that resultant stimulation and sensed experience. The twist in the experimental story, however, came when Granqvist’s results failed to replicate Persinger’s earlier results. Lacking any independent replication of results, Granqvist was left to conclude that Persinger’s own conclusions have been too singular and one-sided and that other factors besides magnetic stimulation of temporal lobes have been stealthily slithering into his results. Persinger’s response, upon reading Granqvist study, accused Granqvist of using the wrong measuring equipment to conduct his study! However entertaining the reading of this correspondence simply is, Granqvist’s study and Persinger’s response also remind readers of the importance of conducting scientific studies carefully (and often tediously), of agreeing on terms, of accounting for variables, and of independently replicating results. For the results, specifically those of temporal lobe stimulation, extend beyond the basement shelves of libraries and reach into the core of interpretations of religious experience.
For over twenty years, Persinger had been conducting studies on the effect of specific patterns of magnetic stimulation on the temporal lobe of his subjects. His conclusion based on his years of research was that such stimulation, in a sensory-deprived environment, evoked a response in 80% of subjects whereby subjects “sensed [the] presence of a sentient being” (Granqvist 1). Persinger concluded, then, that religious experiences and ‘God-presences’ could be induced in subjects; he had established a variable of causality in religious experience, not just variables of correlation.
Granqvist, in attempting to replicate Persinger’s previous studies, set up an experiment that utilized the same magnetic wave pattern for subjects in similar sensory-deprived environments. Granqvist’s study, however, besides measuring the outcome of the experiment using an EXIT Scale – a scale describing somatosensory experiences (and of which Granqvist questions the internal consistency of) – included three predictor scales of variability. Also added was the Mystical Experiences Scale as at outcome variable. Granqvist, furthermore, took pains to ensure the double-blindedness of his study: subjects were unaware of whether they were placed in the magnetic-stimulation group or the placebo group and experimenters were similarly unaware of whether subjects had received magnetic stimulation or not.
Granqvist’s two main conclusions directly contradicted Persinger’s: Granqvist’s study found no statistical difference between the laboratory experience of his placebo and that of his experimental group and, furthermore, Granqvist concluded that, based on the predictor scales of The Temporal Lobe Signs Inventory, The Tellegen Absorption Scale, and The New Age Orientation Scale, it was the increased suggestibility of subjects that correlated with the probability of whether or not they would sense a sentient being during the procedure or have a mystical-like experience. Persinger, in his response to Granqvist, countered that the proper magnetic wave pattern had never been administered to Granqvist's subjects, that it was administered with faulty equipment, and that the laboratory comforts of Granqvist’s subjects were not comparable to those of Persinger’s (all this despite the fact that it was Persinger’s equipment which Granqvist was using and whose instructions of use he was following). Granqvist himself countered again, rebuffing Persinger’s faulty apparatus accusation and maintaining that Persinger’s own experiments have never properly incorporated the double-blind experiment method – or at least have not properly documented such incorporation, even if double-blind methods have been used. In a word, Granqvist accuses Persinger’s results of being biased.
Granqvist’s study, while not supporting Persinger’s conclusions, does – in a tangential way – support a final over-arching conclusion that “religious experiences are most likely complex and multifactorial, involving motivational, cognitive, and setting factors [3,30] that cannot be equated with easily defined neurophysiological states.” (Granqvist 6). His conclusion, an apt one, is: do not rush to conclusions. More important than the specific data included in this dialogue, however, is the reminder of how critical experimental design, parameter definitions and documentation of procedure is. Without these measures, researchers can draw any wild conclusions they want; and even if their conclusions are not wildly extravagant their conclusions at least become questionable upon examination. Scientific theories are based on observation, measurement and repetition – priorities that religious experience may not always embrace. But if scientists are to speak about religious experience they must maintain strict scientific principles if they want their conclusions to be considered credible, even within religious world-views.