Our story so far. Purves et al (1996) reported that the wagon-wheel illusion occurs in continuous illumination. They argued that this implies that we perceive visually in sequential episodes, a radical new idea with important implications for perception.
I then stumbled across (while catching up on my _Current Contents_ scanning) a new article by Pakarian & Yasamy (2003) which said that the illusion did not occur in continuous light. I wrote to Dr. Pakarian for a reprint, and asked him specifically about the Purves finding in relation to his own. Within a few short hours, I had a reprint and curteous reply all the way from sunny (and not so Sunni) Tehran. I need not have bothered querying him about Purves. The whole point of the paper was to report that they failed to replicate Purves' finding despite 15 subjects and an apparently sophisticated methodology. All subjects, as expected, did report the effect under fluorescent light. P & Y were in touch with Dr. Purves, presumably to ensure that their technique was adequate, as they thanked him in their acknowledgement. P & Y didn't speculate concerning the source of their failure to replicate. They did say "It appears to us that the results reported by Purves et al, which have recently been used as some evidence for discreteness of our conscious perception in some articles (Crick and Koch, 2003 [yes, _that_ Crick]; VanRullen and Koch, 2003), are not replicable." So we have a major mystery here. Beth, Tom's students, and Dale Purves may well say "Oh, to have seen what I have seen". But what about the rest of us? Let a thousand wheels spin! Let two thousand eyeballs examine them! And Dr. Pakarian in his e-mail to me, although still at the Institute for Studies in Theoretical Physics and Mathematics, this time gave his affiliation as the School of Cognitive Sciences. So that crack about time off from atomic bomb- making was indeed ill-advised. Stephen ___________________________________________________ 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]
