Does your astrological sun sign predict your personality? In our book, Signs of Life: The Origin of Astrological Symbolism and Its Relation to the Human Psyche, Polly Dukes and I conclude that it doesn’t—but that doesn’t mean that the symbolism of astrology is worthless!
What Is Sun-Sign Astrology?
Sun-sign astrology is the belief that the geocentric position of the sun in the ‘sign’ of the zodiac at the time of someone’s birth somehow determines that person’s personality.
The signs of the zodiac are twelve equal divisions of 30° each of the ecliptic, starting at the vernal equinox, or 0° Aries. They are thematic codifications of seasonally-associated star-constellations which are positioned behind the sun at the roughly corresponding time of year.
Sun-sign astrology assumes that a person takes on the associated characteristics of whatever sign the sun is “in” at their birth, as a general token of their personality. In Signs of Life, Polly Dukes and I describe a number of studies which have put forward convincing evidence that there is in fact no support for this assumption.
We know that there is evidence for associations between longer, more general seasonal periods of birth and later personality, in particular for behavioural-personality factors such as schizophrenia, bipolar disorder, major depression and manic-depressive psychosis (an excess for winter/spring births in all cases), 1Torrey, E. F., Miller, J., Rawlings, R. & Yolken, R. H. (1997). Seasonality of Births in Schizophrenia and Bipolar Disorder: A Review of the Literature. Schizophrenia Research, 28(1), 1-38.,2Davies, G., Welham, J., Chant, D., Torrey, E. F. & McGrath, J. (2003). A Systematic Review and Meta-Analysis of Northern Hemisphere Season of Birth Studies in Schizophrenia. Schizophrenia Bulletin, 29(3), 587-593. panic disorder (an increase for births in September to December),3Castrogiovanni, P., Iapichino, S., Pacchierotti, C. & Pieraccini, F. (1999). Season of Birth in Panic Disorder. Neuropsychobiology, 40(4), 177-182. novelty or sensation seeking (an increase for winter-born males)4Eisenberg, D. T., Campbell, B., Mackillop, J., Lum, J. K. & Wilson, D. S. (2007). Season of Birth and Dopamine Receptor Gene Associations With Impulsivity, Sensation Seeking and Reproductive Behaviors. PloS one, 2(11). and suicide (a peak occurring in late spring or summer).5Woo, J. M., Okusaga, O. & Postolache, T. T. (2012). Seasonality of Suicidal Behavior. International journal of environmental research and public health, 9(2), 531-547. Although the differences between seasons are statistically significant, the risks of developing such conditions from being born in these times of the year are nevertheless low.
However our question is more specifically concerned to ask if there is any evidence for an association between the traditional keyword-themes of the shorter, approximately one-month-long periods of the sun-sign at birth and corresponding personality traits measured in later life. If there was, one would of course be able to predict personality simply by noting the relevant keyword characteristics of the individual’s natal sun-sign— even easier than predicting aspects of personality by measuring self-report ratings on Eysenck’s ‘extraversion-introversion and ‘neuroticism-stable’ dimensions,6Eysenck, H. J. (1953). The Structure of Human Personality. Methuen. or on those of Cattell’s 16 personality factors.7Cattell, H. E. & Schuerger, J. M. (2003). Essentials of 16PF Assessment. Wiley.
Any reliable associations found between the keyword themes of the natal sun-signs and later personality trait measures would result in more predictive ease and power than ‘mainstream’ measurements of traits in psychometric tests, since all one would have to do to assess personality would be to note the date of birth! This is of course tantamount to asking if there is any evidence to support traditional divinatory (predictive) astrology—at least that part of it that deals with the sun-sign at birth.
Is There Any Evidence for Sun-Sign Astrology?
There have in fact been empirical studies which have looked for correlations between personality factors and keywords of the sun-sign at birth. Over a number of years, Michel Gauquelin gathered keyword personality traits from the biographies of 2,000 sports champions, actors, scientists and writers, and compared these with the astrological keywords (as provided by leading astrological textbooks) of the sun-sign, the Moon-sign, and the sign rising on the eastern horizon (the ‘ascendant’ or ‘rising sign’ in astrological terminology) of each subject at birth.8Gauquelin, M. (1982). Zodiac and Personality: An Empirical Study. Skeptical Inquirer, 6(3), 57-65. Gauquelin however found no significant degree of matching between the subjects’ biographical trait keywords and the keywords of their natal Sun-signs (or those of their Moon-signs or ascendants).
Another study found no association between sun-sign at birth and scores derived from the California Personality Inventory (CPI).9Pellegrini, R. J. (1973). The Astrological “Theory” Of Personality: An Unbiased Test by a Biased Observer. Journal of Psychology, 85, 21-28. This study did seem to find an association with the inventory’s measurement of a ‘femininity’ scale, though later studies failed to replicate even this abstruse association.10Illingworth, D. & Syme, G. (1977). Birthday and Femininity. Journal of Social Psychology, 103, 153-154.,11Tyson, G. (1977). Astrology or Season of Birth: A ‘Split-Sphere’ Test. Journal of Psychology, 95, 285-287.
Studies which have looked for evidence of associations between sun-sign and later occupation in life have found none.12McGervey, J. D. (1977). A Statistical Test of Sun-Sign Astrology. The Zetetic, 1(2), 49-54.,13Tyson, G. A. (1980). Occupation and Astrology or Season of Birth: A Myth? Journal of Social Psychology, 110, 73-78.
An exemplary study which tested whether the keyword traits of a person’s natal sun-sign might correspond with later personality, at least as the latter may be measured by a multiple choice questionnaire, was conducted in 1999 by Jan van Rooij.14van Rooij, J. J. F. (1999). Self-Concept in Terms of Astrological Sun-Sign Traits. Psychological Reports, 84(2), 541-546.
In this study, participants completed a questionnaire which asked them to rate how well certain keyword traits applied to them. The participants were not told that the keywords used were those understood by astrologers to be descriptive of the twelve sun-signs. Following this, their astrological knowledge was assessed by the completion of a second questionnaire, asking them if they knew their sun-sign, and if so, if they could name some keyword traits that were associated with it. The results of the study showed that participants described themselves in terms of their actual natal sun-sign—but only if they had some astrological knowledge (as measured by the second questionnaire). Participants who had no astrological knowledge of sun-signs did not describe their personalities in terms of their sun-sign.
The study by van Rooij thus strongly suggests that sun-signs at birth do not predict personality (and therefore are unlikely to instil it at birth in any way), but only appear to do so in the case of those who have acquired some knowledge of astrology. It would therefore seem that knowledge of (and by implication, some acceptance of) astrological theory alters people’s self-attribution or concept of themselves to be in agreement with that knowledge.
Thus there appears to be no empirical support for the notion that the astrological sun-sign at birth is associated with, or predicts, personality. Rather, the belief that it does, originating from an assimilated knowledge of astrological sun-sign symbolism amongst certain people, becomes a strongly instilled self-concept, which is reflected in self-report ratings.
In our book Polly Dukes and I argue that those aspects of divinatory astrology which examine the zodiacal positions of other astrological “planets” (bodies other than the sun) in the signs could not even theoretically determine personality, as they have nothing to do with the signs themselves, or their origin.
The Continuing Popularity of Sun-Sign Astrology
But what then explains the stubborn persistence and popularity of the belief that one’s astrological sun-sign determines one’s personality? The reason would seem to be the powerful cognitive bias, identified by the van Rooij experiment, in those with prior knowledge of astrology, to arrogate to their self-concept the characteristics of their sun-sign.
We would contend that the reason why this cognitive bias is so powerful is that astrological symbolism deals with a uniquely comprehensive array of the most fundamental archetypes of human nature (we discuss this aspect of the astrological signs in more depth in our book). Thus the bias will always find plausible personality candidates in the descriptions inherent in the sun-signs.
It may be interesting to note that a corollary of this finding is that those people who have internalised a self-concept of their personalities from a knowledge of astrology can be said to have ‘taken on’ their sun-sign personalities. These people do indeed seem to have personalities that align with their sun-sign. But it is important to note that the cause of this is not their sun-sign, but their ‘indoctrinated’ prior knowledge of it. The personalities of those without such prior knowledge are free to assume different forms (though they are no doubt subject to other forms of indoctrination).
Is Astrology Worthless?
Are we then to say that the subject of astrology is worthless? Our response to this question would be overwhelmingly in the negative. For although astrological sun-signs do not predict personality, they represent (as we argue in our book) a uniquely comprehensive array of the most fundamental archetypes of human nature. Indeed it is this aspect of the astrological signs that enabled the cognitive bias of self-concept to gain such a strong foothold in those with knowledge of astrology. It is this characteristic of astrological symbolism that makes the subject supremely interesting and revealing of the human psyche.
This was in part recognised by the famous Swiss psychiatrist Carl Jung when he described astrology as “the sum of all the psychological knowledge of antiquity“. Indeed we go further in our book to describe how the symbolism of the astrological zodiac, of the signs and “planets”, has permeated storytelling, folklore, custom, myth and religion to an extent that has never been appreciated to its full extent.
Our Conclusion
We conclude therefore that, as empirical studies show quite convincingly, your astrological sun-sign at birth does not determine your personality, but that despite this—and more interesting than this—such studies have shown that if you’re indoctrinated by traditionally accurate prior knowledge of the traits of your sun-sign to believe that it does determine your personality, then that indoctrination (not the happenstance of your sun-sign itself, but simply the indoctrinating knowledge), can determine—or at least modify—your personality to fit the characteristics of the sun-sign (as least in so far as ‘personality’ is taken to be what is measured by self-report questionnaires).
Thus, although your sun-sign on its own is not associated with your personality, a prior knowledge of—and by implication, a belief in—the traditional characteristics of your sun-sign may well be. So if you’re knowledgable about the characteristics of your sun-sign, you may well end up internalising a personality that has that sun-sign’s traditional attributes.
Furthermore we suggest that the reason why this cognitive bias is so powerful—to the point where it actually can change personality to fit belief—is because the very symbolism of astrology is based on the most fundamental archetypes of human nature; thus they give ready credence to an internalisation of personality. This being so, although personality is not determined or caused by our sun-sign, we assert that astrological symbolism is far from worthless, but represents a comprehensive and fundamental collection of symbolic archetypes of the human psyche, and for that reason warrants study.
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