View source for Biorhythm (pseudoscience)

==Critical views==

There have been some three dozen published studies of biorhythm theory, but according to a study by [[Terence Hines]], all of those either supported the [[null hypothesis]] that there is no correlation of human experience and the supposed biorhythms beyond what can be explained by coincidence, or, in cases where authors claimed to have evidence for biorhythm theory, methodological and statistical errors invalidated their conclusions. Hines therefore concluded that the theory is not valid.<ref name="Hines_review">{{cite journal|last=Hines|first=Terence|year=1998|title=Comprehensive Review of Biorhythm Theory|journal=Psychological Reports|volume=83|issue=1|pages=19–64|doi=10.2466/pr0.1998.83.1.19|pmid=9775660|s2cid=7823326}}</ref>

Supporters continued to defend the theory in spite of the lack of corroborating [[scientific evidence]], leading to the charge that it had become a kind of pseudoscience due to its proponents' rejection of empirical testing:
{{blockquote|text=An examination of some 134 biorhythm studies found that the theory is not valid (Hines, 1998). It is empirically testable and has been shown to be false. Terence Hines believes that this fact implies that biorhythm theory 'can not be properly termed a pseudoscientific theory'. However, when the advocates of an empirically testable theory refuse to give up the theory in the face of overwhelming evidence against it, it seems reasonable to call the theory pseudoscientific. For, in fact, the adherents to such a theory have declared by their behaviour that there is nothing that could falsify it, yet they continue to claim the theory is scientific. (from Carroll's ''[[The Skeptic's Dictionary]]'')<ref name=ploch/>{{rp|175}}|author=|title=|source=}}

The physiologist [[Gordon Stein]] in the book ''Encyclopedia of Hoaxes'' (1993) wrote:<ref>[[Gordon Stein|Stein, Gordon]]. (1993). ''Encyclopedia of Hoaxes''. Gale Group. p. 161. {{ISBN|0-8103-8414-0}}</ref><blockquote>Both the theoretical underpinning and the practical scientific verification of biorhythm theory are lacking. Without those, biorhythms became just another pseudoscientific claim that people are willing to accept without required evidence. Those pushing biorhythm calculators and books on a gullible public are guilty of making fraudulent claims. They are hoaxers of the public if they know what they are saying has no factual justification.</blockquote>A 1978 study of the incidence of industrial accidents found neither empirical nor theoretical support for the biorhythm model.<ref>{{cite journal | pmid = 662540 | doi=10.2466/pms.1978.46.2.423 | volume=46 | issue=2 | title=No evidence for relationship between biorhythms and industrial accidents | journal=Perceptual and Motor Skills | pages=423–6 | last1 = Persinger | first1 = MA | last2 = Cooke | first2 = WJ | last3 = Janes | first3 = JT| s2cid=24850984 | year=1978 }}</ref>

In [[Underwood Dudley]]'s book, ''Numerology: Or What [[Pythagoras]] Wrought'', he provides an example of a situation in which a magician provides a woman her biorhythm chart that supposedly included the next two years of her life. The women sent letters to the magician describing how accurate the chart was. The magician purposely sent her a biorhythm chart based on a different birthdate. After he explained that he sent the wrong chart to her, he sent her another chart, also having the wrong birthdate. She then said that this new chart was even more accurate than the previous one.<ref>{{cite book |last1=Dudley |first1=Underwood |title=Numerology: Or What Pythagoras Wrought |url=https://archive.org/details/numerologyorwhat0000dudl |url-access=registration |date=1997 |publisher=The Mathematical Association of America }}</ref> This kind of willful [[Credulity|credulous]] belief in vague or inaccurate prognostication derives from [[motivated reasoning]] backed up by fallacious acceptance of [[confirmation bias]], [[Post hoc analysis|post hoc rationalization]], and [[suggestibility]].<ref name="skepdic.com" />

Wilhelm Fliess "was able to impose his number patterns on virtually everything"<ref>{{cite book |last1=Gardner |first1=M |title=Science, Good, Bad, and Bogus}}</ref> and worked to convince others that cycles happen within men and women every 23 and 28 days. Mathematically, Fliess's equation, n = 23x +28y is unconstrained as there are infinitely many solutions for x and y, meaning that Fliess and [[Sigmund Freud]] (who adopted this idea in the early 1890s<ref>{{Cite news|last=Goleman|first=Daniel|date=1985-03-17|title=New Insights into Freud|language=en-US|work=The New York Times|url=https://www.nytimes.com/1985/03/17/magazine/new-insights-into-freud.html|access-date=2020-09-09|issn=0362-4331}}</ref>) could predict anything they wanted with the combination.<ref>{{cite book |last1=Dudley |first1=Underwood |title=Numerology, or, What Pythagoras wrought}}</ref>

The skeptical evaluations of the various biorhythm proposals led to a number of critiques lambasting the subject published in the 1970s and 1980s.<ref>{{cite book |last1=Casti |first1=John L. |title=Paradigms Lost|year=1989 |publisher=Morrow |isbn=9780688081317 |url=https://archive.org/details/paradigmslostima00cast |url-access=registration }}</ref> Biorhythm advocates who objected to the takedowns claimed that because [[circadian rhythm]]s had been empirically verified in many organisms' sleep cycles, biorhythms were just as plausible. However, unlike biorhythms, which are claimed to have precise and unaltering periods, circadian rhythms are found by observing the cycle itself and the periods are found to vary in length based on biological and environmental factors.<ref>{{cite news |last1=Biersdorfer |first1=J.D. |title=Strange Things Happening? Blame Your Biorhythms |newspaper=New York Times}}</ref> Assuming such factors were relevant to biorhythms would result in [[Chaos theory|chaotic]] cycle combinations that remove any "predictive" features.

=== Additional studies ===
Several controlled, experimental studies found no correlation between the 23, 28 and 33 day cycles and academic performance.<ref name=":1">{{Cite journal |last=James |first=Arthur |date=1984 |title=The validity of 'biorhythmic' theory questioned |journal=British Journal of Psychology |volume=75 |issue=2 |pages=197–200 |doi=10.1111/j.2044-8295.1984.tb01891.x |pmid=6733392 |issn=0007-1269}}</ref><ref name=":2">{{Cite journal|last=Peveto|first=Natalia|date=1980-01-01|title=The Relationship of Biorhythms to Academic Performance in Reading.|url=https://digitalcommons.lsu.edu/gradschool_disstheses/3577|journal=LSU Historical Dissertations and Theses|doi=10.31390/gradschool_disstheses.3577 |s2cid=210819305 |doi-access=free}}</ref> These studies include:

==== James (1984) ====
James hypothesized that if biorhythms were rooted in science, then each proposed biorhythm cycle would contribute to task performance.<ref name=":1" /> Further, he predicted that each type of biorhythm cycle (i.e., intellectual, physical, and emotional) would be most influential on tasks associated with the corresponding cycle type. For example, he postulated that intellectual biorhythm cycles would be most influential on academic testing performance.<ref name=":1" /> In order to test his hypotheses, James observed 368 participants, noting their performance on tasks associated with intellectual, physical, and emotional functioning. Based on data collected from his experimental research, James concluded that there was no relation between subjects' biorhythmic status (on any of the three cycle types), and their performance on the associated practical tests.<ref name=":1" />

==== Peveto (1980) ====
Peveto examined the proposed relationship between biorhythms and academic performance, specifically in terms of reading ability.<ref name=":2" /> Through examination of the data collected, Peveto concluded that there were no significant differences in the academic performance of the students, in regards to reading, during the high, low, or critical positions of neither the physical biorhythm cycle, the emotional biorhythm cycle, nor the intellectual biorhythm cycle. As a result, it was concluded that biorhythm cycles have no effect on the academic performance of students, when academic performance was measured using reading ability.<ref name=":2" />