Subject: Re: The Auditory Continuity Illusion/Temporal Induction From: "Richard M. Warren" <rmwarren(at)UWM.EDU> Date: Mon, 12 Dec 2005 10:31:46 -0600Dear Al, I agree completely, Klingons and all. Dick -------------------------------------------- Richard M. Warren University of Wisconsin-Milwaukee Department of Psychology PO Box 413 Milwaukee, WI 53201-0413 Phone: (414) 229-5328 Fax: (414) 229-5219 Email: rmwarren(at)uwm.edu On Dec 9, 2005, at 11:12 PM, Al Bregman wrote: > Dear Dick, > > Your reply to Fatima is much appreciated. The question of "where" a > process takes place in the brain is very complex. The auditory signal > starts at the object that makes the sound. So a Gibsonian might say > that > the external object participates in the process. Then the sensory > system > registers the sound. If the stimulus features that you described as > being > needed for induction to occur have to be registered by the peripheral > auditory system, then at least to that extent, the latter system is > also > involved. Then information is circulated to a number of brain areas. > It > is likely that without the participation of any of these sites, no > induction would be carried out. > > A central question remains: Is there an area of the CNS that is > involved > in auditory induction but not in any other auditory process? That is > what > is required before you could argue that this specific area is the > module > that takes care of auditory induction. Using this strict criterion, > we may > not have enough scientific information to say where *any* auditory > phenomenon is carried out, never mind auditory induction. One might > think > that we can obtain this information from studies involving > brain-imaging . > However, the process of subtraction of a control condition from an > experimental condition in such studies may give misleading answers. > > Let me illustrate this point with a fanciful analogy. Suppose some > Klingon > scientists are interested in exactly where an analysis of variance > (ANOVA) > is carried out in a human-built computer (Klingons have enormous > computers > that compute different functions in different places.) They don't know > exactly how a human-built computer works, but they do know how to > measure > things. In particular, they are able to measure the activity level of > every part of the computer as it carries out a number of statistical > processes. By the clever use of the subtraction technique, they find > that > a certain area of the computer's memory (region A) is more active > during an > ANOVA than is any other part of the computer. [Let me reveal that what > they > have discovered is the high level program that specifies the ANOVA > computation; it is, however, written using other high-order processes, > such > as "sum of squares", as primitives (these primitives being calculated > by > helper programs located elsewhere in the computer).] > > Our Klingon scientists conclude that the ANOVA is carried out in this > region A. Are they right? Well, yes and no. The process is indeed > coordinated there, but is actually carried out all over the computer. > There are helper programs, such as sum of squares, that are located in > other memory regions. There are also the pieces of hardware for > shifting > numbers from one location to another, testing the equality of two > numbers, > adding, multiplying, inputting and outputting numbers, busses for > connecting these pieces of hardware, etc., which are located all over > the > computer. So it is more correct to say that a large part of the > computer > calculates the ANOVA, not just region A. > > It seems to me that this is a direct analogy to the use of the > subtraction > method in fMRI studies. Even assuming that its human practitioners > are as > clever as the Klingon scientists in choosing all the necessary control > conditions, the subtraction method leads them to say that the process > is > *carried out* in the region that shines forth after all subtractions. > The > method effectively discards the contributions of the rest of the brain > to > the process. Studies involving ablation or brain damage have the same > problem. Finding out that the destruction of a particular region > destroys > a certain capacity without affecting any others (a rare finding) still > does > not tell us that the capacity is largely located in that region, only > that > the region is essential for the process. > > The conclusion is that imaging and destruction studies cannot in > themselves > tell us where a process is taking place in the brain. Since those are > the > two most powerful techniques that we now have available, this > conclusion is > discouraging. What can we do about it? Well, we can be aware that the > brain is an organ whose parts are highly interactive. Maybe it is not > particularly productive to ask "where" a process is going on. A better > question might be "how". How can processes distributed all over the > brain > collaborate in carrying out a process such as auditory induction. > > Best holiday wishes to all, > > Al > > ---------------------------------------------------- > Albert S. Bregman, > Emeritus Professor > Psychology Dept., McGill University > 1205 Docteur Penfield Avenue > Montreal, Quebec > Canada H3A 1B1 > > Voice & Fax: +1 (514) 484-2592 > ---------------------------------------------------- >