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]
