Foggy perception slows us down

Paolo Pretto, Jean Pierre Bresciani, Gregor Rainer, Heinrich H. Bülthoff

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


Visual speed is believed to be underestimated at low contrast, which has been proposed as an explanation of excessive driving speed in fog. Combining psychophysics measurements and driving simulation, we confirm that speed is underestimated when contrast is reduced uniformly for all objects of the visual scene independently of their distance from the viewer. However, we show that when contrast is reduced more for distant objects, as is the case in real fog, visual speed is actually overestimated, prompting drivers to decelerate. Using an artificial anti-fog-that is, fog characterized by better visibility for distant than for close objects, we demonstrate for the first time that perceived speed depends on the spatial distribution of contrast over the visual scene rather than the global level of contrast per se. Our results cast new light on how reduced visibility conditions affect perceived speed, providing important insight into the human visual system.

Original languageEnglish
Article numbere00031
Issue number1
Publication statusPublished - 2012 Oct 30

ASJC Scopus subject areas

  • General Neuroscience
  • General Biochemistry,Genetics and Molecular Biology
  • General Immunology and Microbiology


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