Discomfort glare influences covert visual attention.

At night, the driver may be exposed to glare from other vehicles, leading to reduced visual sensitivity, but also to visual discomfort. The present study explores the possibility that discomfort from glare disturbs visual perception through covert spatial attention mechanism. Posner's seminal experiment (Posner, 1980) was replicated with and without glare to measure covert attention. Thirty-one participants had to detect a target, with cued and uncued locations, as soon as possible, left or right of a fixation cross. Two conditions of glare were presented (weak and strong individual levels of discomfort). As the participants were either asked to click on a button or look at the target, it was also possible to measure the motor-response time, visual response time and spatial accuracy of the first fixation on the target that were collected with a distant eye-tracker. Some effects of the discomfort were found on covert attention (RT), where discomfort degrades covert attention, with a dose-effect. Unexpectedly, gaze accuracy is higher with glare than in the control condition, while it is lower with strong compared to weak glare. These results are discussed in relation to our initial theoretical hypotheses, and also in relation to night driving. Availability of resources. De-identified data and analysis code are available on the Open Science Framework (OSF) via an anonymous link: view-only link.