Terence Hines - Pseudoscience and the Paranormal

The hypothesis that there are astrological influences on extroversion and introversion has often been raised, although never in the exact fashion described above. Dean (1977) has reviewed these studies, which offer no support for any proposed astrological influence. For example, Forlano and Ehrlich (1941) examined the birth dates of 7,527 male college students and found no effect of any sun sign on extroversion and introversion. Lim (1975) used 163 subjects and found no correlation between extroversion and introversion and sun signs. Nor did Lim find any influence of moon signs on this personality variable. Mayo, White, and Eysenck (1975) reported a study of 2,324 individuals that seemed to give impressive support to the hypothesis of astrological influence on extroversion and introversion. In this study, subjects filled out a personality questionnaire; the results of that questionnaire were correlated with the subjects’ birth dates. Later work by Eysenck, reported in Eysenck and Nias (1982), showed that the original result was artifactual. Specifically, the subjects had knowledge of their astrological sign and the type of personality that is supposed to correlate with each sign. In one study (Eysenck and Nias 1982), 1,160 children, who were presumably unaware of astrological theory, were studied. There was no correlation between extroversion or introversion and astrological sign in these children. Another study reported by Eysenck and Nias was designed to test directly the prediction that subjects who had specific knowledge of the alleged astrological relationships between birth date and sign and personality would show greater correlation between sign and personality than those who didn’t. One hundred twenty-two subjects were divided into three groups: those who were knowledgeable about astrological claims about personality, those who had a “borderline” knowledge, and those who had no knowledge about the alleged relationships. Both the “no knowledge” and “borderline” groups showed no correlation between astrological sign and extroversion or introversion. However, “the knowledgeable group… showed a marked tendency to assess themselves in accordance with astrological predictions” (p. 56). Thus, the original Mayo, White, and Eysenck (1978) results were due to the subjects’ astrological knowledge, which was apparently extensive (Eysenck and Nias 1982). This knowledge biased at least some subjects in the way they reported their personality on the questionnaire. If a subject knew, for instance, that people born under Aries are supposed to be extroverted and he knew that he had been born under Aries, he reported a more extroverted personality. An earlier study by Delaney and Woodward (1974) also demonstrated such behavior. In this study, fifty-five high-school students read personality descriptions based on their birth dates. Half received descriptions that were consistent with traditional astrological teachings (“Aries are extroverted,” for example) and half received descriptions that were just the reverse (e.g., “Aries are introverted”). After reading the descriptions, they were asked to fill out a personality questionnaire. They were told that the purpose of the study was to “attempt to see if astrology has any real predictive value” and that the questionnaire was “concerned with your personality not the personality which was astrologically predicted” (p. 1214). The responses on the questionnaire were influenced by the descriptions of personality that had been read, whether or not those descriptions were those of classical astrology. That is, if a subject was an Aries and had read that Aries people are extroverted, the responses on the subject’s personality questionnaire showed a more extroverted personality. If an Aries was told that Aries people are introverted, the subject’s questionnaire responses showed a tendency toward introversion. In addition to showing that the original Mayo, White, and Eysenck results were not due to astrological influence, these studies further demonstrate how subtle uncontrolled experimental variables can produce results that look as if they support astrological influences. They further show the importance of conducting further studies to confirm the results and control previously uncontrolled variables.

Eysenck and Nias (1982) also failed to find any astrological influence on another major personality variable, emotionality versus stability, although subjects’ knowledge at first resulted in spurious correlations between astrological sign and this personality variable as well.

Another common claim made by astrologers is that a couple’s compatibility is determined, at least in large part, by their sun signs. That is, two people who have “compatible” sun signs will have a better chance of making a successful marriage than two people whose sun signs are “incompatible.” Several studies have shown that in fact sun signs have no influence on marriage or divorce (Dean 1977; Culver and Ianna 1984). In these studies one obtains the birth dates for divorced and nondivorced couples. If sun signs have any influence, pairs with incompatible sun signs should be overrepresented among divorced couples and underrepresented among nondivorced couples. The studies reviewed in these two references reveal no influence of sun signs on marriage or divorce rates.

Culver and Ianna (1984) have further pointed out that astrologers disagree widely on which sun signs are compatible. Figure 8, taken from Culver and Ianna (pp. 132–33), shows the sun signs that Righter (1977), King (1973), Norvell (1975), and Omarr (1972) consider compatible and incompatible. Inspection of the figure shows the great degree of disagreement among these four popular astrologers, each of whom claims validity for his system, but not on the basis of any real data. The lack of agreement among astrologers should not be seen as reducing the importance of the research findings on sun signs and rates of marriage and divorce. These studies show that no combination of sun signs was associated with marriages or divorces. In other words, these studies examined all possible relationships between sun sign and compatibility and found that in no case was there any relationship. They did not simply test the few specific predictions made by astrologers.

Carlson (1985) has performed an extremely thorough and well-designed study of astrological predictions. This study is unique in that the help and cooperation of the astrological “profession” was sought and obtained. “So that the participating astrologers should be respected by the astrological community, we sought the advice of the National Council for Geocosmic Research” (p. 420). Further, the astrologers involved agreed before the study was conducted that the procedures and design constituted a fair test of astrological predictions.

In the first part of the study, 177 subjects were recruited through newspaper ads. Based on their birth date, time, and place, their horoscopes were constructed and then interpreted by the astrologers associated with the study. Each subject was given an interpretation of three different horoscopes. One of the interpretations was of their own horoscope, while the other two were interpretations of horoscopes of two other randomly chosen participants in the study. If astrologers were able to divine personal information from a horoscope, then the subjects should have been able to choose the interpretation of their own horoscope over the interpretations of other individuals’ horoscopes at a rate better than chance.

In the second part of the study, 116 subjects took the California Psychological Inventory (CPI), a widely used test of personality in normal (nonpathological) individuals (Megargie 1972). The astrologers were then given one individual’s horoscope and the CPI personality profile of three subjects. One of the CPI profiles was that of the same subject whose horoscope was given to the astrologer. The astrologers’ task in this part of the study was to pick the CPI profile that matched the horoscope.