  Previously, we reported that the hypomagnetic field obtained by the 100-fold
deprivation of the geomagnetic field affected human cognitive processes as
estimated in several computer tests. The exposure to the hypomagnetic field
caused a statistically significant increase both in the task processing time
and in the number of errors. The magnitude of this magnetic effect, averaged
over 40 healthy subjects and more than 10^5 separate trials, was about 1.7%. In
the present work, the results of a simultaneous study are described, in which
the right eye of each subject was video recorded, while the subject performed
the tasks. It has appeared that the pupil size grows in the hypomagnetic field.
This effect has been calculated based on the treatment of a large data set of
about 6.10^6 video frames. Averaged all over the frames, the magnetic effect on
the pupil area was about 1.6%, with high statistical confidence. This is the
first laboratory study in which the number of separate trials has been large
enough to obtain rather smooth distribution functions. Thus, the small effect
of the hypomagnetic field on humans has become evident and statistically valid.
