The present study was conducted to investigate whether superimposed electromagnetic fields could control flickering light perceptions caused by the activity of a stimulated retina. To show the capabilities of electromagnetic control, we designed two coil systems and investigated the magnetic flux distributions of superimposed extremely low frequency (ELF) magnetic fields from the coils. Furthermore, we examined the superimposed effect for the modification of perception and discovered that the ELF co-stimuli can control retinal sensitivities partially for perception.
When the ELF field frequencies were varied in the range of 10-50 Hz, threshold variations for the perception were observed as the effect of the co-stimuli to the temporal side at 40 Hz and to the eyeball side at 20 Hz. These results show a definite advantage by employing the superimposed ELF fields on the two previously mentioned locations with a close examination of the properties of the flicker sensations.