Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Foggy perception slows us down

30.10.2012
Max Planck scientists show that, contrarily to what was previously believed, speed is overestimated in fog

Fog is an atmospheric phenomenon that afflicts millions of drivers every day, impairing visibility and increasing the risk of an accident. The ways people respond to conditions of reduced visibility is a central topic in vision research. It has been shown that people tend to underestimate speeds when visibility is reduced equally at all distances, as for example, when driving with a uniformly fogged windshield.


The visualization facility at the Max Planck Institute for Biological Cybernetics in which the research was conducted. The screen covers 230° horizontal and 125° vertical field of view, filling the entire human visual field to provide full immersion in the virtual environment.

Picture: Jan Soumann / Max Planck Institute for Biological Cybernetics Tübingen


The visualization facility at the Max Planck Institute for Biological Cybernetics in which the research was conducted (user perspective): The screen covers 230° horizontal and 125° vertical field of view, filling the entire human visual field to provide full immersion in the virtual environment.

Picture: Jan Soumann / Max Planck Institute for Biological Cybernetics Tübingen

But what happens when the visibility decreases as you look further into the distance, as happens when driving in true fog? New research by Paolo Pretto at the Max Planck Institute for Biological Cybernetics in Tübingen, Germany, published in eLife, reveals that people tend to overestimate their speed when driving in fog-like conditions and therefore naturally tend to drive at a slower pace.

Poor visibility conditions affect millions of drivers around the world. Thousands of them die each year in a car accident. Excessive speed constitutes a major causal factor for these car accidents. For the first time Paolo Pretto and his fellow scientists, in the department for Human Perception, Cognition and Action of Heinrich Bülthoff at the Max Planck Institute for Biological Cybernetics in Tübingen, Germany, showed how fog biases speed perception and revealed the perceptual mechanisms underlying this bias, providing important insights into the human visual system.

In particular, they showed that contrarily to what was previously believed, speed is overestimated in fog, because visibility is poorer in the central than in the peripheral area of the visual field. The researchers also show that the behavioral consequence of this speed overestimation is a natural tendency to drive at a slower pace.

Using a new approach Paolo Pretto and his colleagues performed a series of experiments involving experienced drivers and high-quality virtual reality simulations. “We have shown that speed can also be overestimated at a low contrast of the surrounding scenery when driving a car”, explains the psychologist. “This occurs notably when contrast is not reduced uniformly for all objects of the visual scene, but proportionally to their distance from the viewer, as is the case in fog.”

In one experiment drivers were presented with two different driving scenes and asked to guess which scene was moving faster. In the reference scene the car was driving at a fixed speed through a landscape under conditions of clear visibility. In the test scene it was moving through the same landscape, again at a fixed speed, but with the visibility reduced in various ways.

The experiments showed that drivers overestimated speeds in fog-like conditions, and underestimated them when the reduction in visibility did not depend on distance. Further experiments confirmed that these perceptions had an influence on driving behavior: drivers recorded an average speed of 85 kilometers per hour when the visibility was good. This dropped to 70 kilometers per hour in severe fog. However, when visibility was reduced equally at all distances like in a fogged windshield instead of fogged surroundings, the average driving speed increased to 100 kilometers per hour.

Based on previous work, the scientists developed the theory that the perception of speed is influenced by the relative speeds of the visible regions in the scene. When looking directly into the fog, visibility is strongly reduced in the distant regions, where the relative motion is slow. Yet, it is preserved in the near regions, where the motion is fast. This visibility gradient would lead to speed overestimation. To test this theory, they repeated their experiments with new drivers under three different conditions: good visibility, fog, and an artificial situation called “anti-fog” in which visibility is poor in the near regions and improves as you look further into the distance. As predicted, the estimated speed was lower in anti-fog than in clear visibility and fog. Conversely, the driving speed was 100 kilometers per hour in anti-fog, compared with 70 kilometers per hour in good visibility and 50 kilometers per hour in fog.

Overall the results show that the perception of speed is influenced by spatial variations in visibility, and they strongly suggest that this is due to the relative speed contrast between the visible and covert areas within the scene. Therefore, drivers should better listen to their visual system when it prompts them to decelerate in foggy weather.

More Information about Paolo Pretto and his work:
http://www.kyb.tuebingen.mpg.de/research/dep/bu/motion-perception-in-vehicle-simulation.html

eLife is a joint initiative of the Howard Hughes Medical Institute, the Max Planck Society, and the Wellcome Trust. Along with a growing number of public and private research funders worldwide, these three organizations recognize that the communication of research results is as fundamental a component of the research process as the experiments themselves.

More Information about eLife: http://www.elifesciences.org

Original Publication:
Pretto P., Bresciani J.-P., Rainer G., Bülthoff H. H. (2012) Foggy perception slows us down. eLife. doi: 10.7554/eLife.00031.001
Contact:
Dr. Paolo Pretto
Phone: +49 7071 601-644
E-mail: paolo.pretto@tuebingen.mpg.de
Stephanie Bertenbreiter (Public Relations)
Phone: +49 7071 601-1792
E-mail: presse-kyb@tuebingen.mpg.de
Printable images can be obtained at the Public Relations Office. Please send a proof upon publication.

The Max Planck Institute for Biological Cybernetics works in the elucidation of cognitive processes. It employs about 300 people from more than 40 countries and is located at the Max Planck Campus in Tübingen, Germany. The Max Planck Institute for Biological Cybernetics is one of 80 research institutes that the Max Planck Society for the Advancement of Science maintains in Germany and abroad.

Stephanie Bertenbreiter | Max-Planck-Institut
Further information:
http://tuebingen.mpg.de/en/homepage/detail/foggy-perception-slows-us-down.html

More articles from Life Sciences:

nachricht Topologische Quantenchemie
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

nachricht Topological Quantum Chemistry
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

Chances to treat childhood dementia

24.07.2017 | Health and Medicine

Improved Performance thanks to Reduced Weight

24.07.2017 | Automotive Engineering

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>