Instead, people who experience such symptoms do so because they expect
that they will occur, the findings suggest.
Dr Gunnhild Oftedal and associates at the Norway University of Science
and Technology in Trondheim recruited 17 subjects who "regularly
experienced pain or discomfort in the head during or shortly after mobile
phone calls lasting between 15 and 30 minutes."
The participants were tested during mobile phone
radiofrequency exposure and sham
exposure, without knowing which session was which. Each
session lasted 30 minutes, and 65 pairs of trials were conducted.
As reported in the medical journal Cephalalgia, the subjects said they
felt an increase in pain or discomfort during 68 per cent of all trials.
The degree of symptoms was not associated with the order of trials.
The researchers observed no statistically significant correlations
between actual exposures and the subjects' reports of symptom severity,
and no effects of exposure on changes in heart rate or blood pressure.