The Effect of Differences in Day and Night Lighting Distributions on Drivers' Speed Perception

Previous research has shown that changes to contrast levels in the visual environment caused by fog can affect drivers' perceptions of speed. It is not easy, however, to extrapolate these results to other driving scenarios in which contrast is affected, such as during nighttime driving, because the measure of contrast is more complex when considering factors such as the illumination provided by headlights. Therefore, we investigated the differences in lighting distribution patterns between day- and nighttime driving on speed perception using prerendered 3D scenarios representing driving on a rural road. A two-alternative forced-choice design based on the method of constant stimuli was utilised, with 32 participants viewing a series of pairs of scenarios (day vs. night driving) from a driver's perspective while indicating for each pair whether the second scenario was faster or slower than the first scenario. Our results indicated that speed discrimination accuracy was minimally affected by changes in lighting distribution patterns between day and night.