Original Paper

Journal of Comparative Physiology A

, Volume 188, Issue 3, pp 235-237

The light sensitivity of the human visual system depends on the direction of view

  •  F. ThossAffiliated withCarl-Ludwig-Institute of Physiology of the University Leipzig, Liebigstr.27, 04103 Leipzig, Germany
  • ,  B. BartschAffiliated withCarl-Ludwig-Institute of Physiology of the University Leipzig, Liebigstr.27, 04103 Leipzig, Germany
  • ,  D. TellschaftAffiliated withCarl-Ludwig-Institute of Physiology of the University Leipzig, Liebigstr.27, 04103 Leipzig, Germany
  • ,  M. ThossAffiliated withTheoretical Chemistry, Technical University of Munich, Lichtenbergstr.4, 85747 Garching, Germany

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Abstract.

The near-stable North-South orientation of the natural geomagnetic field provides an ideal basis for navigation. Sailors have used it since ancient times, animals for much longer. Various mechanisms have developed for this purpose. Experiments have pointed to a connection between orientation in the geomagnetic field and light perception. Such observations are supported by theoretical considerations. The underlying interaction should also modulate the light sensitivity of the visual system. Recently we demonstrated the effect of an oscillating field. Here we report the existence of a weak influence of the static field on visual sensitivity in man. By comparison with control experiments, if the directions of view line and field vector coincide the perception threshold of a light stimulus is slightly but significantly increased. This significance is lost if the view line deviates by 10 degrees from the field direction.

Compass orientation Geomagnetic field Light sensitivity Threshold recording Radical-pair mechanism