Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!philabs!cmcl2!harvard!panda!genrad!decvax!decwrl!cooper@pbsvax.dec.com From: cooper@pbsvax.dec.com Newsgroups: net.sci Subject: Re: Parapsychology: more on the decline effect. Message-ID: <4031@decwrl.DEC.COM> Date: Thu, 3-Jul-86 18:57:58 EDT Article-I.D.: decwrl.4031 Posted: Thu Jul 3 18:57:58 1986 Date-Received: Sat, 5-Jul-86 07:08:13 EDT Sender: daemon@decwrl.DEC.COM Organization: Digital Equipment Corporation Lines: 156 Bill Jefferys ({allegra,ihnp4}!{ut-sally,knew}!utastro!bill, bill@astro.UTEXAS.EDU) has claimed as an explanation for the decline effect in parapsychology (the tendency for the scoring rate to decrease over the course of an experiment) the following: >Not if you have selected for further study precisely those individuals >who scored high initially, and if you include those earlier trials >in the overall test results. I admitted that such the error of inappropriately mixing screening with testing trials might have occurred on rare occasions in the parapsychological literature (as a chemist might admit that dirty test tubes may have been the actual cause of some published results). I thought it was *very* unlikely that any such flaw was the source of any claimed evidence for the decline effect which had appeared in a refereed parapsychology journal or other legitimate piece of parapsychological literature, however. The error would have been too obvious in this case to have been missed by the referees. I therefore challenged him to produce even a single example of this, by "direct or indirect" citation. He responded with: >The University of Texas doesn't subscribe to parapsychological journals, >so I can't satisfy you completely. However, > >A quick trip to the library turned up the book, "Parapsychology: Science >or Magic?", by J. E. Alcock (Pergamon, 1981). His discussion and explanation >of the "Decline Effect" is basically the same as the one I suggested. This is a legitimate and reasonable answer to my request. It is the type of thing which I had in mind when I was speaking of an "indirect" citation. Unfortunately, in this case, it is not enough. I own or have read a fair amount of the critical literature, but I do not own nor have I read this book. I checked for it in the MIT library system but no copy is owned by them either. This is, of course, no criticism of the book. It just means that I cannot effectively respond without further information. Since you have access to this book please post the citations to the literature which the author uses to support his/your thesis. If he does not provide such citations, then this book does not even partially answer my challenge. I do not question that others have made this accusation before. I have seen or heard it made a number of times. I have just not seen any concrete evidence to back it up. >He also cites Spencer Brown ("Probability and Scientific Inference", 1957) >who showed that data from 100,000 published random numbers, analyzed using >the Quartile method in use at Duke University, showed a very significant >Quartile Decline effect. Sorry, I fail to see how this supports your thesis at all. G. Spencer-Brown is best known for his book "The Laws of Form." (I'm doing this off the top of my head so I can't give publication info) It is the thesis of this work that there is something fundamentally wrong with all existing formal logic, and therefore, with the foundations of all modern mathematics. A friend of mine once said of it, "It would clearly be a work of genius if only it made any sense at all." Many people who read it, including those with a fair amount of mathematical sophistication, are left with the feeling that Spencer-Brown seems to have said *something* of importance but it's completely unclear what. Spencer-Brown considered himself a critic of parapsychology. He felt that parapsychologists felt that they were investigating a physical phenomena while in reality, all they were doing was demonstrating that probability and statistical theory were fundamentally flawed (of course). Specifically, he believed that published random number tables were not "random". He never really specified the nature of their non-randomness except that it would conveniently result in the success of many parapsychological tests whatever use they made of the table (the dominant methodology for randomization during the 50's in parapsychology was to use published random number tables, such as the RAND 1,000,000 random digits, to determine the targets for the experiment in one or another ways). I should say that I would consider the demonstration of such an error in elementary statistics and probability to be a *very* unexpected outcome. In my opinion, it would, however, justify the most basic claim of parapsychologists, i.e., that psi is something real and important. I have heard similar statements by other parapsychologists. Of all the resolutions I can think of for the mystery of psi, this one would have one of the largest impacts on the practice of science and engineering. Anyway -- To prove his point Spencer-Brown performed the cited experiment. He entered a random number table (probably the RAND table, but I don't remember for sure) at two arbitrary points. He declared one entry point as being for his targets and the other as being for his calls. He then matched the next N digits (I'll take Bill's word that it was 100,000) one by one and came up with a significant number of matches and a scoring decline. (I may be misremembering the details here, its been years since I read it. I have the feeling that his actual procedure was a bit more complex than this, but I'm pretty sure that this was the essence). I won't bother to discuss generally the various interpretations of this experiment here, as its irrelevant to the point. If Spencer-Brown did what he claimed (entered the table with the first pair of entry points he tried) then this is either an irrelevant fluke, or *disproves* your point, since the decline effect appears without screening trials to be inappropriately included with the data. If Spencer-Brown actually tried multiple sets of entry points until he found some which gave many early hits, then it still gives no support to your claims. No one is denying that a decline effect would be produced if someone committed this obvious and egregious error (although, the apparent *continuous* decline which appears to be the characteristic of the actual effect would not be produced this way). Spencer-Brown was a *critic* of parapsychology, however unconventional, rather than a parapsychologist. His behavior therefore cannot be taken to say anything about the way that parapsychologists conduct experiments. >I also would guess that some of the articles cited by Marks (1986: _Nature_ >vol 320, pp. 119-124) would treat this issue, particularly Refs. 42-45. >Unfortunately, I don't have access to any of them so I don't know for >sure. I am only familiar with three of those four references. None of these touch upon the issue. I doubt if the fourth supports your thesis. First, because if John Beloff, probably Great Britain's leading parapsychologist, had made such a claim, I suspect I would have heard about it. Secondly, the decline effect does not seem to me to be particularly germane to the topic of the paper, i.e., the inappropriateness of strict repeatability as a criterion for the acceptance of evidence of psi. Third, I have heard Beloff discuss this topic elsewhere, and he made no mention of the decline effect. As for the other references, none that I have read provide any solid support for your thesis. I am willing to accept an "indirect" reference through the critical literature if I have access to the work in question. But a reference to a set of references covering a moderate amount of the technical critical literature of the last 20 years, with a comment of "something here probably supports my claim" is hardly a reasonable response. >The odd thing is that the "Decline Effect" is cited by parapsychologists >as "Evidence" of the reality of Psi. In any other field, such an "effect" >would be cited as evidence that the original observations were flawed >in some way, or were the result of a statistical fluke. Unless it were found repeatedly under a variety of experimental conditions and scientists involved were at all competent. Then they would give it a name (such as "the decline effect" or "conditioning extinction" or "pulsar slowdown" :-) and attempt to study it. Topher Cooper USENET: ...{allegra,decvax,ihnp4,ucbvax}!decwrl!pbsvax.dec.com!cooper INTERNET: cooper%pbsvax.DEC@decwrl.dec.com Disclaimer: This contains my own opinions, and I am solely responsible for them.