Fog & Perception Ask Dave a weather question

Dave Thurlow, Host

 
One of the scariest moments while in a car is driving in fogÉwhen there's hardly any visibility at all. It's a dangerous situation that causes drivers to slow down. But there is new research that suggests people may not be slowing down as much as they think. Hi, I'm Dave Thurlow and this is The Weather Notebook. I recently spoke with perceptual psychologist Bob Snowden at the University of Wales, who is heading up this research. Here's part of our conversation:

Bob: "Well, what we're doing is looking to see what the effects of fog are upon our perception of movement. We knew that in certain laboratory conditions as we change the stimuli on the screen as we make the screen less contrasty, i.e. less black and white, the stimuli moving on that screen will appear to slow down. So, a bright dot moving across a dark screen appears to move faster than a dim dot moving across a dark screen."

Dave: And you found connections to this in people driving through fog.

North side of the Golden Gate Bridge disappearing into the fog: NOAA Photo

Bob: "Right, yes. One thing that fog does is scatter light and therefore reduce the contrast. Reduce the amount of black and white between things in the scenery as you move along in a car. So, it predicted that if that little visual illusion we had in the laboratory actually transfers out of the laboratory into real life, then we should have the illusion that as it becomes foggier things appear to slow down."

Dave: Even though you're driving at the same rate of speed?

Bob: "Even though you're driving at the same speed, it'll feel as if you're driving slower."

Tomorrow we'll hear more from Professor Snowden as he takes his theories from the lab to the real world. Our shows producer is Bryan Sejvar and our engineer is Sean Doucette. If you have any questions about weather, you can call us at 1-888-724-6001 and leave them on our machine. The Weather Notebook is a production of the Mount Washington Observatory, underwriting is provided by Subaru, the beauty of all wheel drive with major funding provided by the National Science Foundation.