This paper is concerned with the influence of scientists’ prior beliefs on their judgments of evidence quality. A laboratory experiment using advanced graduate students in the sciences (study 1) and an experimental survey of practicing scientists on opposite sides of a controversial issue (study 2) revealed agreement effects. Research reports that agreed with scientists’ prior beliefs were judged to be of higher quality than those that disagreed. In study 1, a prior belief strength X agreement interaction was found, indicating that the agreement effect was larger for general, evaluative judgments than for more specific, analytical judgments. A Bayesian analysis indicates that the pattern of agreement effects found in these studies may be normatively defensible, although arguments against implementing a Bayesian approach to scientific judgment are also advanced.

The Influence of Prior Beliefs on Scientific Judgments of Evidence Quality

There is a widespread belief that cancer is caused, at least in part, by aberrant mental processes. A corollary of this belief is that cancer may be cured by the application of the mind. These ideas are fostered in Australia by a popular book “You can conquer cancer” by lan Gawler, a veterinary surgeon who attributes, at least in part, the development and subsequent cure of his own cancer to such processes. Critical examination of these beliefs finds evidence in their support to be lacking. None the less, many patients with cancer in this country follow the book’s advice, often on the basis that it “at least can do no harm”. While some patients may be aided to come to terms with their disease and to lead more fulfilling lives by taking up meditation and the positive approach to living that is described in the book, it also contains recommendations about orthodox treatments, life-style and diet which, If adopted uncritically, could be quite detrimental. The potentially harmful effects of accepting such unproved ideas about cancer need to be known more widely. Furthermore, because his ideas are making such an impact on the dayto-day treatment of cancer in this country, Gawler owes it to the community to justify, with evidence, his claims that by meditation patients with cancer may be enabled to achieve a cure of their disease in a way that is unattainable with orthodox medical treatment alone. In many ways the achievements of medical science in treating advanced cancer are not well-enough known. They include the cure of the majority of children with acute leukaemia; the cure of 80% or more of patients with cancer of the testis (the most common cancer in young men) and of Hodgkin’s disease; the cure of about half the cases of high-grade malignant lymphomas; and the achievement of prolonged remissions and possibly cures in 20-30% of adults with acute leukaemia. Patients with advanced malignancies of several other types, including prostatic, breast and ovarian cancers, small-cell carcinoma of the lung, the chronic leukaemias and multiple myeloma, all can achieve improvements in the quality of life as well as the prolongation of survival. In some cases, such as with the use of hormonal agents for breast and prostatic cancers, the treatment that is required to effect these results has little toxicity. As a consequence of these advances, any visitor to a haematology or oncology clinic in a large teaching hospital today would be able to see a number of patients for whom a diagnosis of advanced cancer was made in the 1970s. None the less, taken over all, science has made only a modest impact on the problem of cancer. Cancer remains the second most common cause of death in our community, and no effective specific treatment is available yet for a number of common malignancies such as cancer of the pancreas, non-small cell carcinoma of the lung and advanced adenocarcinoma of the bowel. Even where effective treatment can be offered, to many patients the potential side-effects of surgery, radiotherapy and chemotherapy are perceived as unacceptable relative to their possible benefits. Furthermore, doctors often are criticised for their inability to discuss bad news sympathetically and for their failure to impart hope. Therefore, it should be no surprise that some patients are inclined to seek solutions outside the medical profession. Currently, a widely held belief is that the solution lies in alterations to mental attitudes and a return to “natural” living. It is postulated that mental attitudes determine the body’s immune status and that this, in turn, determines the risk of the development of cancer. Thus, the hypothesis runs, if mental attitudes may lead to cancer, changing those attitudes may cure cancer. Interest and belief in this approach among the general public in Australia is so strong that a popular book on the subject beguilingly entitled “You Can Conquer Cancer” by lan Gawler, a veterinary surgeon, has sold many thousands of copies and, in fewer than six years, already is into its seventh printing. It is the most readily available book on cancer to be found in bookshops and health food stores throughout the nation. In contrast, books which provide broadly based information about cancer in a popular form and in a manner which the medical profession could recommend confidently (for example, those by Glucksberg and Singer, Baum, Clyne, and Bryan and Lyall) generally are displayed much less prominently, if at all. The situation now has been reached in some parts of the country that almost every patient with a newly diagnosed cancer either buys the book or is given it by a well-meaning relative or friend. Furthermore, thousands of patients, as well as their friends and relatives, have joined support groups around the nation that actively promote the views that are expressed in the book. The medical profession has maintained a low profile on the matter hitherto but, in my opinion, the growing popularity of the book and of the practices that are mooted in it are such that silence no longer is appropriate. The Gawler phenomenon now is having a significant

A Second Coming

Although there has been over a century of formal empirical inquiry, parapsychologists have clearly failed to produce a single reliable demonstration of “paranormal,” or “psi,” phenomena. Although many parapsychological research projects have been carried out under what have been described as well-controlled conditions, this does not by itself make a science, for unless and until it can be demonstrated that paranormal phenomena really exist, there is no subject matter around which a science can develop. Indeed, parapsychologists have not even succeeded in developing a reasonable definition of paranormal phenomena that does not involve, or imply, some aspect of mind-body dualism. Moreover, parapsychology has developed several principles (such as the experimenter effect) which can be used to explain away failures, and the use of these principles contributes to making the psi-hypothesis unfalsifiable.The “anything goes” attitude in parapsychology, which seems to lend credence to virtually any “paranormal” claim, serves to weaken the credibility of parapsychological endeavors in the eyes of critics. This general willingness to suspend doubt is another indication that parapsychology is more than the quest to explain anomalous experiences, as is claimed. It is argued in this paper that parapsychological inquiry reflects the attempt to establish the reality of a nonmaterial aspect of human existence, rather than a search for explanations for anomalous phenomena.

Parapsychology: Science of the anomalous or search for the soul?

Over the past hundred years, a number of scientific investigators claim to have adduced experimental evidence for “psi” phenomena – that is, the apparent ability to receive information shielded from the senses (ESP) and to influence systems outside the sphere of motor activity (PK). A report of one series of highly significant psi experiments and the objections of critics are discussed in some depth. It is concluded that the possibility of sensory cues, machine bias, cheating by subjects, and experimenter error or incompetence cannot reasonably account for the significant results. In addition, less detailed reviews of the experimental results in several broad areas of psi research indicate that psi results are statistically replicable and that significant patterns exist across a large body of experimental data. For example, a wide range of research seems to converge on the idea that, because ESP “information” seems to behave like a weak signal that has to compete for the information-processing resources of the organism, a reduction of ongoing sensorimotor activity may facilitate ESP detection. Such a meaningful convergence of results suggests that psi phenomena may represent a unitary, coherent process whose nature and compatibility with current physical theory have yet to be determined. The theoretical implications and potential practical applications of psi could be significant, irrespective of the small magnitude of psi effects in laboratory settings.

The anomaly called psi: Recent research and criticism

The present paper investigated whether academic psychologists show a tendency to rate the quality and appropriateness of scientific studies more favorably when results and conclusions are consistent with their own prior beliefs (i.e., confirmation bias). In an online experiment, 711 psychologists completed a questionnaire (e.g., about their belief in astrology) and evaluated research that was presented in form of a short abstract in which 40 different behaviors (e.g., alcohol consumption, willingness to share money) have been tried to be predicted. The research to be evaluated varied on three dimensions which were all manipulated between subjects: (1) the predictors of the 40 behaviors (either Big Five or astrological factors), (2) the methodological quality of the study (low, medium, high), and (3) the results and subsequent conclusion of the study (confirmation or disconfirmation of the hypotheses). Factor-analyzed scores of participants’ ratings on 8 scales, resulting in 2 factors termed quality and appropriateness, served as dependent measures. The main result of the study is a two-way interaction: Psychologists tended to evaluate results qualitatively higher when they conformed to their own prior expectations, as in this case, when astrological hypotheses were disconfirmed.

Biased evaluation of abstracts depending on topic and conclusion: Further evidence of a confirmation bias within scientific psychology.

A faculty of psychologists is much more skeptical regarding the existence of ESP than beginning psychology students. The students, however, are unaware of this discrepancy. The greater acceptance of ESP by the students is due to cultural and psychological factors which encourage such beliefs. The skepticism of academic psychologists arises because the evidence for ESP has failed to meet generally accepted scientific standards. Among these are (1) a replicable experiment, (2) the elimination of more plausible explanations, (3) isolation of an independent variable, (4) a coherent theory, and (5) practical applications. Much of the research in ESP may be criticized because of the lack of accurate reporting, improper design, and inadequate controls. In view of these considerations behavioral scientists should make a public disavowal of belief in ESP.

The Scientific Credibility of ESP

R. A. McConnell ( 3 ) has criticized our article (4 ) concerning the scientific credibility of ESP, listing eight statements which he regards as misleading or incorrect. Pollowing is our appraisal of these criticisms: ( a ) He objects to our phrase, \"The recognition of ESP requested by McConnell (1 )\" on the grounds that he did not use the term \"request.\" W e feel that the general tenor of his article justifies our paraphrase. (b ) H e objects to our contention that Upton Sinclair was an untrained observer whose study lacked adequate controls. W e agree with McConnell that the reader should inspect Sinclair's monograph and judge for himself. (c ) McConnell objects to our attributing to him the term \"law\" in reference to an observed regularity, namely, the shrinkage of the ESP effect over time. H e also objects to the word \"shrinkage\" and to our failure to distinguish permanent losses of ESP ability from temporary declines. W e admit that the term \"law\" was a paraphrase and was used in a broad sense, but we did stress in our article that the area of ESP has yet to provide any cause-effect relationship which could be called \"laws\" In any strlcter sense. Again, we feel that this change of terms did not affect our argument. ( d ) McConnell states that it is untrue that he makes no mention of the lack of practical applications of ESP and cites point two of his artide which states that \"ESP is contrary to both common sense and practical experience in real life setting situations where, in fact, the laws of chance have been found to govern.\" W e stand corrected. What we should have said was that McConnell did not recognize the implications of the failure of ESP to show itself in practical situations such as gambling, where even the tiniest advantage can so easily be detected. ( e ) McConnell justifies his speculation about the reasons for the failure of H . Forwald to demonstrate a psychokinetic effect in Pittsburgh on the grounds that \"when a failure occurs after a long series of successful experiments, it is permissible to speculate about cnuses.\" W e counter that failure is the rule rather than the exception in ESP experiments, and that ad hoc speculation about causes is the most prevalent form of theory in this area. ( f ) McConnell states that 16 and not 15 arguments against ESP were included in his article ( 2 ) . Sixteen points were indeed included but the last and sixteenth point is not an argument but rather an explanation for the polarization of attitudes towards ESP. ( g ) McConnell states that the term \"exper~rnent\" rather than \"data\" should have been used in our reference to \"possible biased selection of data.\" Although both are real factors in critiques of research, we agree that in the present context the term \"experiment\" should have been used. McConnell's other points appear to be concerned only with an elaboration of points which were treated briefly in out discussion. None of McConnell's objections appear to us to damage our position. At the end of his anicle he offers copies of bibliographies for the skeptical scientist. W e would like to request that McConnell indicate by an asterisk in the bibliographies, those articles which provide evidence for a cause-effect relationship; that is, which identify some controlling variable which we can study in our laboratory and expect to make a difference in the occurrence of ESP.

Samuel Moss

Papers

The Scientific Credibility of ESP

Comments on McConnell's Paper