I haven't yet read the Purves paper, but if memory serves, the idea of distinct perceptual segments was proposed back in the 1960's by John Stroud. (Whose business cards read "General Consulting Scientist") He referred to it as the psychological moment and believed it divided our experience into intervals of approximately 100 msec. It has been a long time since I have heard it referred to so my recall may be a bit hazy. -- Doug Wallen, Psychology Dept. (507) 389-5818 Minnesota State University, Mankato [EMAIL PROTECTED] 23 Armstrong Hall Mankato, MN 56001
> From: "Stephen Black" <[EMAIL PROTECTED]> > Organization: Bishop's University > Reply-To: "Teaching in the Psychological Sciences" <[EMAIL PROTECTED]> > Date: Fri, 09 Apr 2004 10:25:24 -0500 > To: "Teaching in the Psychological Sciences" <[EMAIL PROTECTED]> > Subject: Wagon-wheel illusion again > > 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] --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
