Exposure to a 50 Hz, 100 mu T magnetic field significantly decreased reaction time on a difficult visual task compared to sham exposure, but did not affect cardiovascular performance.
RCT (n=100)
Double-blind
Does 50 Hz magnetic field exposure affect visual task performance and cardiovascular parameters in healthy adults?
One hundred subjects, males and females with ages ranging between 18 and 48 years, were studied under both field-exposed and sham-exposed conditions. A 50 Hz, 100 mu T magnetic field (MF) was used. To examine the effect of field exposure on performance, a two-alternative, forced-choice, duration-discrimination task with three levels of difficulty was used. The subject's task was to decide which of two sequentially presented light flashes had the longer duration. The standard duration was 50 ms, and the alternative durations were 65, 100, or 125 ms. Both reaction time and percentage of correct responses were recorded for each subject. MF and sham exposure were for 9 min each. Blood pressure and heart rate were also measured before and following MF exposure and sham-exposure trials. The study was performed double blind, with the exposure order counterbalanced. Compared to sham exposure, MF exposure significantly decreased reaction time on the hardest level of the performance task. MF exposure did not reliably affect percentage correct or cardiovascular performance. It was demonstrated that a relatively high level of statistical power was the basis for the observed MF effect, and the need to pay closer attention to power levels in future research is discussed.
Whittington et al. (1996) reported an RCT. 50 Hz magnetic field exposure vs. Sham exposure was evaluated on Reaction time, percentage of correct responses, blood pressure, and heart rate. Exposure to a 50 Hz, 100 mu T magnetic field significantly decreased reaction time on a difficult visual task compared to sham exposure, but did not affect cardiovascular performance.