Don, Though I can hardly claim to have any engineering background, I know that rear-view mirrors, as well as side mirrors, can distort reality. Perhaps polarization is not the process that is going on here, but I did find a website with two extremely interesting pictures. If you click on this site, scroll down to see the two pictures, side by side, of surf through a horizontal filter and through a vertical filter. The thing that really fascinated me is that the first one seems to be demonstrating what the earlier wagon-wheel illusion explanation described. It appears to be broken up and separated in lines. I wonder if this is why I saw that illusion on the truck's spokes. Take a look, and read the description further down:
http://www.polarization.com/water/water.html Here's a description of how a car's rearview mirror's glare-resistant setting works...could also have had something to do with creating that illusion?? http://auto.howstuffworks.com/question20.htm And finally (this has been fun, though I have no idea whether any of it explains why I saw that illusion!), here's an explanation of how polymers in rearview mirrors make it self-dimming. (Click on "next" and "previous" below each picture and chart.) http://www.ee.ucla.edu/~eamuri/vu-graphs/yablonovitch/yablonovitch2.html Beth Benoit University System of New Hampshire ----- Original Message ----- From: "Don Allen" <[EMAIL PROTECTED]> To: "Teaching in the Psychological Sciences" <[EMAIL PROTECTED]> Sent: Wednesday, April 07, 2004 8:10 PM Subject: Re: Wagon-wheel illusion again > Beth- > > I've never heard of a polarized mirror. How does that work? But Stephen's > idea about flickering light in real-world situations makes a lot of sense. > Lane divider strips are often on & off (e.g. a passing zone). That could > have produced a strobe effect. > > -Don. > > Beth Benoit said: > > I'm wondering if observing it in the mirror was the cause of the > > illusion. (Especially if the mirror was a polarized one???) > > Beth Benoit > > ----- Original Message ----- > > From: "Stephen Black" <[EMAIL PROTECTED]> > > To: "Teaching in the Psychological Sciences" <[EMAIL PROTECTED]> > > Sent: Wednesday, April 07, 2004 5:17 PM > > Subject: Wagon-wheel illusion again > > > > > >> Just recently we were discussing the wagon-wheel illusion, and if I > >> recall correctly, both Tom Alloway's students and Beth Benoit > >> reported seeing the phenomenon under steady illumination while > >> driving down the highway. > >> > >> By coincidence, there's a report just out (well, I just spotted it > >> anyway) investigating the phenomenon. They say it doesn't occur under > >> steady illumination under laboratory conditions. So students of Tom > >> and Beth, science says you didn't see what you saw. I append the > >> abstract below. It has the distinction of coming from theoretical > >> physicists and from Iran, a rather unusual source on both counts, it > >> seems to me. > >> > >> If I may speculate on the discrepancy between what science found and > >> what people experienced, I wonder if under real-life conditions such > >> as driving down the highway, what appears to be steady illumination > >> may actually be flickering. For example, if the light illuminating the > >> wheels was interrupted by trees or by posts along the highway, it > >> would flicker, and so understandably cause the effect. I seem to > >> recall that epileptic seizures have been triggered in susceptible > >> individuals by such flickering when driving down a road lined with > >> trees. > >> > >> Stephen > >> > >> Perception. 2003;32(11):1307-10. > >> Wagon-wheel illusion under steady illumination: real or illusory? > >> Pakarian P, Yasamy MT. > >> > >> School of Intelligent Systems, Institute for Studies in Theoretical > >> Physics and Mathematics (IPM), Niavaran Square, Tajrish, Tehran, PO > >> Box 19395-5746, Iran. [EMAIL PROTECTED] > >> > >> Wheels turning in the movies sometimes appear to rotate backwards. > >> This is called the wagon-wheel illusion (WWI). The mechanism of this > >> illusion is based on the intermittent nature of light in films and > >> other stroboscopic presentations, which renders them as a series of > >> snapshots rather than a continuous visual data stream. However, there > >> have been claims that this illusion is seen even in continuous light, > >> which would suggest that the visual system itself may sample a > >> continuous visual data stream. We examined the rate of this putative > >> sampling and its variations across individuals while in different > >> psychological states. We obtained two results: (i) WWI occurred in > >> stroboscopic lights as expected, (ii) WWI was never reported by our > >> subjects under continuous lights, such as sunlight and lamps with DC > >> power source. Thus, WWI cannot be taken as evidence for discreteness > >> of conscious visual perception. > >> ___________________________________________ > >> Stephen L. Black, Ph.D. tel: (819) 822-9600 ext 2470 > >> Department of Psychology fax: (819) 822-9661 > >> Bishop's University e-mail: [EMAIL PROTECTED] > >> Lennoxville, QC J1M 1Z7 > >> Canada > >> > >> Dept web page at http://www.ubishops.ca/ccc/div/soc/psy > >> TIPS discussion list for psychology teachers at > >> http://faculty.frostburg.edu/psyc/southerly/tips/index.htm > >> _______________________________________________ > >> > >> > >> --- > >> You are currently subscribed to tips as: [EMAIL PROTECTED] > >> To unsubscribe send a blank email to > > [EMAIL PROTECTED] > >> > > > > > > > > --- > > You are currently subscribed to tips as: [EMAIL PROTECTED] > > To unsubscribe send a blank email to > > [EMAIL PROTECTED] > > > -- > > > > > --- > You are currently subscribed to tips as: [EMAIL PROTECTED] > To unsubscribe send a blank email to [EMAIL PROTECTED] > --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
