Measuring drivers’ visual information needs during braking: A simulator study using a screen-occlusion method

• Driving simulator study measured participants’ braking behaviour in the absence of visual information.
• Such a situation may occur in real traffic when a driver is temporally distracted.
• Participants stopped too early when the screen was occluded.
• Participants underestimated distance in the virtual environment.

It is commonly accepted that vision plays an important role in car braking, but it is unknown how people brake in the absence of visual information. In this simulator study, we measured drivers’ braking behaviour while they had to stop their car at designated positions on the road. The access to visual information was manipulated by occluding the screen at the start of half of the braking trials, while the temporal demand was manipulated by varying the time-to-arrival (TTA). Results showed that for the longer TTA values (⩾6 s), participants in the occlusion condition stopped too early and at variable positions on the road as compared to the control condition. In the occlusion condition, participants were likely to apply an intermediate brake pedal depression, whereas in the control condition participants more often applied low or high pedal depressions. The results are interpreted in light of a distance estimation test, in which we found that participants underestimated the actual distance by 70%.