The human visual threshold depends on direction and strength of a weak magnetic field

Abstract

Completing our investigations concerning influences of weak magnetic fields on the visual discrimination threshold, we have investigated 30 subjects (20 female, 10 male) under rotation of the geomagnetic field without change in field strength. We related the thresholds to the values measured in the unchanged field. Comparison with a control experiment shows that correspondence between viewing and field direction results in a significant decrease of the threshold. The significance is lost if the angle between the directions is set to 20 degrees. On the basis of these and our earlier results an attempt is made to give a very simple description of the connection between field direction, field strength, and the change in the visual discrimination threshold.

Magnetic alignment in mammals and other animals

“…Cremer- Bartels et al (1983) found a decrease of human night vision acuity induced by reversals of the horizontal component of the ambient magnetic field. Recently, a similar finding was reported by Thoss and Bartsch (2003) who demonstrated an increase of light sensitivity in a situation when the viewing direction and magnetic field lines are aligned. The effect was already abolished by differences of 20 • between the two parameters.…”

“…Although all early studies pointed towards a mechanism involving magnetite crystals (Baker et al, 1983;Kirschvink et al, 1992) the picture has changed markedly with the latest MA studies. By now, radical-pair processes (Schulten et al, 1978;Ritz et al, 2000) and the location of the magnetoreceptors in the eye have become more likely (Thoss et al, 1999(Thoss et al, , 2000(Thoss et al, , 2002Thoss and Bartsch, 2003). The recently revealed magnetosensitive capacity of the human cryptochrome 2 adds on to this line of evidence (Foley et al, 2011).…”

Influence of a 902.4 MHz GSM signal on the human visual system: Investigation of the discrimination threshold

“…This effect could, of course, influence the function of the visual system. These results, together with our positive findings with weak static magnetic fields [Thoss et al, 2002;Thoss and Bartsch, 2003], suggested to us that it would be useful to investigate the influence of sub-thermal RF exposure on visual sensitivity by the visual discrimination threshold (VDThr), which is a basic property of the visual system.…”

“…Our previous investigations on the influence of the geomagnetic field on the VDThr [Thoss et al, 2002;Thoss and Bartsch, 2003] are used here as a positive control for this current investigation. For those experiments, we used the same method for the estimation of the VDThr, and it turned out to be very sensitive for the detection of small changes in the threshold.…”

Health effects of extremely low‐frequency magnetic fields: reconsidering the melatonin hypothesis in the light of current data on magnetoreception

“…As mentioned above, phylogenetic considerations as well as recent considerations on the role of the magnetic sense suggest the possibility of its existence also in humans, a view that is supported by different experimental observations. These involve the influence of manipulations of the Earth's MF on the human visual threshold (Thoss et al ., ; Thoss and Bartsch, ), the influence of the direction of the Earth's MF on sleep and on EEG during sensory‐motor coordination tasks (Ruhenstroth‐Bauer et al ., , ), neurophysiological response to slowly time‐varying MF that suggests actual sensing of these fields Capone et al ., ; (Carrubba et al ., , 2009; Robertson et al ., ) and the ability of human cryptochrome to restore magnetosensitivity in a transgenic model of Drosophila (Foley et al ., ).…”