In an initial report, human volunteers (n=58, 29 male, 29 female, mean age 29 ± 5.1 years) were exposed to 1.97 GHz (UMTS-like) signal using a dipole antenna producing either 0.63 W/kg (high dose) or 0.063 W/kg (low dose) as modeled within the cortex of the left temporal lobe of the brain. During exposure (or sham exposure), subjects were administered 4 different visual perception tests, each administered 3 times (corresponding to 2 exposure levels and 1 sham exposure). The authors report no statistically significant differences in visual perception due to exposure. In related studies, participants (n = 40) were exposed at 0, 0.037, or 0.37 W/kg (10 gram peak in cortex) during 4 attention tests measuring visual perception (Vienna reaction test, vigilance test, Vienna Determination test, critical flicker and fusion frequency). No effect on components of attention, reaction time, motor activity time, or correct/false response was observed.