EFFECT ON VISUAL ACUITY AND DISCOMFORT FROM HIGHBEAM GLARE IN NATURALISTIC CONDITIONS ON INDIAN ROADS (Paper 806)

Our study is to understand whether pupil diameter changes and gaze point fixation time affects biological (majorly pedestrian) motion detection in mesopic light conditions and high-beam glare of an oncoming car from the context of Indian roads. Eye movement data and pupil dilation data was collected with a wearable eye tracker (Tobii Eye Glasses I) in naturalistic conditions by conducting a set of controlled and uncontrolled experiments. In the controlled experiment drivers (amateurs and professionals) were exposed to rapid sequence of head lamp light intensity from a stationary car on the adjacent lane, stationed at a fixed distance from the experimental (participant’s) car. Our findings showed that: 1) Pedestrian detection and tracking measured as a function of eye fixation time was very low (~0.5s) when the oncoming car had a high-beam on, 2) Rate of change of pupil size during light intensity transitions was high and led to partial blindness as the participant’s eyes were unable to accommodate such rapid changes in the intensity of light. In the second experiment, the data was collected while driving in real-time traffic . The findings supported the observations made in the previous experiment and pointed out possible effect on decision making that might lead to fatal accidents. Pupil data revealed that the multi-lane roads with proper lighting were far low in risk in comparison to undivided two lane roads. The data also showed that in the absence of external street lights the visual acuity increased when the experimenting car had high beam on, thereby leading to better chances of spotting a pedestrian and detecting his/her movement.  Hence, to reduce the disabling and discomfort glare on self, the drivers turn-on the high beam. The findings support the indirect effect of glare on visual system and hence possible cause of accidents and help in building innovative solutions.