Human responses to graded light exposure in the temporal visual field during central visual tasks

Indoor light reaches occupants through a visual field simultaneously used for ongoing visual activity, yet ocular exposure is commonly characterized by scalar measures of magnitude and spectrum. This study examined responses to graded light exposure delivered to the temporal visual field while central task-display conditions were maintained. Thirty-three participants completed a within-subject experiment under four calibrated conditions corresponding to regional melanopic spatial doses of 0.00, 30.79, 61.58, and 92.50 lx; eye-level melanopic equivalent daylight illuminance (mEDI) was retained as a complementary scalar measure. Electrodermal activity, limited-channel EEG, cognitive performance, and subjective responses were assessed. Resting-state mean SCR amplitude was higher under all active conditions than under the near-dark reference, while prefrontal β and parietal α2 power differed mainly at the two higher exposures. All active conditions showed higher 2-back accuracy, whereas DCCS showed no significant condition effect. Visual comfort was lower at 92.50 lx and positive affect at 61.58 lx. The results show differentiated responses to spatially constrained ocular light exposure during ongoing visual activity. Regional melanopic spatial dose complements scalar mEDI by retaining spatial exposure information, although its independent contribution cannot be separated from melanopic magnitude in this design.