How die this affect us? Read on. Does driving in the dark make YOU speed? Navigating at night tricks our brains into thinking we’re travelling slower than we are
When you drive you rely on your brain’s ability to process how fast the ground in front of you is speeding past, according to a new study.
Driving in the dark or in fog makes it more difficult to see objects moving past, making it seem like you are travelling more slowly than you really are.
This is because you rely on the whole road and not just the edges, the researchers have said.
A new study by the University of Leeds examined how people assessed how fast they were moving while driving.
The results could also explain how animals routinely move through the world by following demarcated paths, trails or runways, the researchers said.
HOW THE STUDY WORKED
The study used a driving simulator to test whether human steering was influenced by visual speed signals.
The textured ground either side of the road – on the inside and outside of bends – was manipulated to move artificially faster or slower than the driving speed.
It found a driver’s steering responded to the average ground speed, irrespective of which side moved faster or slower.
This suggested human brain uses the ground movement signal from across the whole of the scene to guide steering, and not just the road edges. When travelling across a ground surface we experiences the apparent perceptual motion of texture elements, referred to as optic flow.
When the optic flow is degraded, for example by the presence of fog or driving at night, this can reduce the perceived speed.
‘Whereas increases in flow quality or quantity, like driving with a seated position close to the ground along narrow country lanes, would increase perceived speed,’ the study said.
Lots of species are sensitive to the movement of objects around them as they move, including bees, flies, birds, desert ants and humans. Associate Professor Dr Richard Wilkie, co-author of the study, said ‘different species are sensitive to optic flow and one control solution is to maintain the balance of flow symmetry across visual fields.’
But he said it is not clear whether animals are sensitive to changes in asymmetries when steering along curved paths.
Road edges alone provide enough information for successful steering, but the brain also uses flow speed information to guide steering.
But he said ‘while asymmetric flow-speed conditions of the type simulated in this study are unlikely to occur naturally, the speed information from the global flow field can vary considerably across different real-world environments.
‘Conditions where the quality of flow is degraded, for example the presence of fog or driving at night, can reduce the perceived locomotor speed, whereas increases in flow quality/quantity for example driving with a seated position close to the ground along narrow country lanes would increase perceived speed.
‘Our findings indicate that such conditions could cause systematic steering errors even when there are clear visual markings for the position in lane and future steering requirements