Years ago, I went through a phase in which I was fascinated by astrology. This phase eventually came to an end, and I believe it was exposure to Christian teachings against astrology that first turned me away from this practice. At some point, I also came across a blog post called ‘What do you mean “test astrology?”’ It contained a very long list of summaries of scientific studies debunking the predictive power of astrology. Unfortunately, that blog is now gone. I will be doing a similar compilation of studies debunking astrology, though nowhere as comprehensive – I simply don’t have the time!

Before personality typing, there was astrology. If anything, astrology could be considered a forerunner of modern personality tests. Astrology basically dictates that the positions of celestial bodies at the time of an individual’s birth influence future personality, preferences, and the like. Some argue that astrology is not meant to be predictive, but that is a nonsense point. If there is no predictive power to it, then it is at best an entirely meaningless waste of time. (For the worst, you can go check out what a Persian manuscript had to say about zodiac signs).

Research studies against astrology

1. Astrologers try to match study subjects with the correct natal chart. In a recent study (from 2024), 152 astrologers were asked to match study subjects with the correct natal charts. Personal details of 12 anonymous volunteers were provided, and for each volunteer, 5 astrological charts were given. Just one of these charts was drawn using the volunteer’s birth data, and the astrologers were tasked with figuring which one this was. Only experienced astrologers who were confident in their ability were chosen for the study. Overall, they “performed in a manner statistically indistinguishable from random guessing.” Moreover, the experience level of the astrologers ultimately did not give them an advantage over less seasoned astrologers.

2. Can date of birth tell us anything about a person’s intelligence or personality? The answer is no. But in regards to how this answer was reached… data from over 15,000 people was obtained and analyzed. Previous studies that had looked into the relationship between intellect, personality, and date of birth tended to lack large sample sizes, which can be problematic statistically. Therefore, the research team of this study aimed for a huge sample size. Despite the hefty amount of data they were able to get, the researchers had to conclude, “In no cases did date of birth relate to individual differences in personality or general intelligence.”

3. A University of California study was designed to meet the standards of both scientists and astrologers. In 1983, researcher Shawn Carlson decided to test the accuracy of astrological natal charts in a double-blind study. Subjects undertook a personality test and also had astrological charts done by astrologers. The astrologers were then tasked with identifying which personality test profile went with which astrological chart. The astrologers were unable to do so at a rate that exceeded random chance.

4. Extensive personal data was not enough for astrologers to match volunteers with birth charts. Across the country in Indiana, researchers presented astrologers with plenty of information on 23 volunteers, from career assessment data to life histories to results of a personality test, and even pictures of the volunteers. The astrologers were tasked with finding the natal chart that was drawn for each volunteer out of 23 charts provided. Though the astrologers appeared confident in their ability, they were unable to do better than non-astrologers or exceed the odds of chance.

5. What effect do zodiac signs have on sex drive, sexual infidelity, marriage, divorce, political views, and selfishness? Little to none, according to Charles Reichardt’s findings. He obtained data relevant to his study from the General Social Survey database, garnering a sample size of 53,000 individuals. Across the board, differences in each of the areas mentioned above were negligible for each zodiac sign, except for the random statistically significant difference which tended to be very minor. For example, never-married status for Sagittarius was higher than average – by a meager 1.5%. Sometimes, a statistical difference went in the opposite direction predicted by astrology, such as a 2% deficit of sexual activity for Leo compared to other signs. The author concludes, “I’ve performed quite a few additional tests, besides the ones reported here, and I’ve found none that provide support for astrology in any meaningful way.”

6. Researchers hypothesized that astrology CAN predict people’s personalities, and they were refuted by their own research. One hundred and ninety six subjects underwent two personality tests and data was isolated for 13 personality variables. These personality variables were compared with data from astrological charts that had been drawn for the same subjects. The association between personality test data and astrological data “was less than what would be expected on a chance basis” and therefore “the hypothesis was rejected.”

7. No relationship exists between extroversion, introversion, neuroticism, psychoticism and zodiac signs. Students from New Zealand University took a personality test, and then the researchers checked for differences in the above personality dimensions between odd and even signs and water and non-water signs. None were found.

8. Can astrology help you find a lasting marriage? Apparently not. Researchers analyzed 66,063 marriages that took place between 1968 and 2001. Information from a Swedish database was used, which is ideal because belief in astrology is low in Scandinavia and therefore the likelihood of intentional efforts to fulfill astrological predictions is decreased. Pairs were categorized according to zodiac compatibility and were ranked on a spectrum from least favorable to most favorable. Per the study results, astrologically favorable unions were not more numerous. The divorce risk of astrologically favorable unions was similar to less favorable unions.

9. Indian astrology purportedly reveals intelligence, but scientific testing discovered otherwise. Horoscopes were created for 200 teenagers, half of which were intelligent and the other half mentally handicapped. Astrologers were then invited to judge random horoscopes and determine which ones belonged to bright kids and which to mentally handicapped ones. Twenty-seven astrologers, with an average of fourteen years of experience, and a team of astrologers from an institution took on the challenge. However, their performance at detecting which was which was “no better than tossing a coin.”

10. Can either Western or Chinese astrology predict if someone will get sick and die? Back during the pandemic, a research team decided to test two systems of astrology (Western and Chinese) in order to uncover any “predisposition to COVID-19 infections or mortality.” Two thousand, five hundred and forty-five patients that had landed in the ER with COVID retrospectively served as study subjects. The researchers were unable to find any relationship between zodiac sign (whether Western or Chinese) and the risk of infection or death from COVID.

If the stars don’t say anything about people, then what does astrology itself say about its fans?

This is not flattering, but a study found that a belief in astrology is correlated with narcissism and lower intelligence.

Ouch. Well, I’m glad it’s just a correlation and not set in stone for everyone. The association with narcissism was the strongest of all the variables studied, with a small but still significant inverse effect for intelligence.

Knowing all this, a good way to respond the next time someone tells you that their sign is such-and-such is to say, “The only thing that tells me about you for sure is that you don’t know that astrology doesn’t work.”

References:

1. Greenberg, S. & Ferretti, A. (2024, July 21). Study Report: Can astrologers truly gain insights about people from entire astrological charts? Clearer Thinking. https://www.clearerthinking.org/post/can-astrologers-use-astrological-charts-to-understand-people-s-character-and-lives-our-new-study-pu

2. Hartmann, P., Reuter, M., & Nyborg, H. (May 2006). The relationship between date of birth and individual differences in personality and general intelligence: A large-scale study. Science Direct. https://www.sciencedirect.com/science/article/abs/pii/S0191886905004046?via%3Dihub&__cf_chl_tk=BDFpwgHMQm1bTXyVeexu1gNjAOnKRebdyBcW9qKoBr0-1771555063-1.0.1.1-MQhYsHsg4Sidwp3MgBC4T6SJY3BnXmotQBvMlEedy3c

3. Carlson, S. (April 1983). Double-Blind Test of Astrology. Escholarship. https://escholarship.org/content/qt0b40b045/qt0b40b045.pdf

4. McGrew, J.H. & McFall, R.M. (1990). A Scientific Inquiry Into the Validity of Astrology. Journal of Scientific Exploration, Vol. 4, No. I, pp. 75-83. http://www.skepticalmedia.com/astrology/Scientific%20Inquiry%20into%20Astrology.pdf

5. Reichardt, C.S. (2010). Testing astrological predictions about sex, marriage, and selfishness. Skeptic, Vol. 15 (4). https://go.gale.com/ps/i.do?id=GALE%7CA228905559&sid=googleScholar&v=2.1&it=r&linkaccess=abs&issn=10639330&p=AONE&sw=w&userGroupName=oregon_oweb&isGeoAuthType=true&aty=geo

6. Hume, N. & Goldstein, G. (July 1977). Is there an association between astrological data and personality? Wiley Online Library. https://onlinelibrary.wiley.com/doi/10.1002/1097-4679(197707)33:3%3C711::AID-JCLP2270330321%3E3.0.CO;2-H

7. Saklofske, D., Kelly, I.W., & McKerracher, D.W. (March 1982). An Empirical Study of Personality and Astrological Factors. ResearchGate. https://www.researchgate.net/publication/233244739_An_Empirical_Study_of_Personality_and_Astrological_Factors

8. Helgertz, J. & Scott, K. (2020, October 19). The validity of astrological predictions on marriage and divorce: a longitudinal analysis of Swedish register data. Springer Nature. https://link.springer.com/article/10.1186/s41118-020-00103-5#Abs1

9. Narlikar, J.V. (2013). An Indian test of Indian astrology: Indian astrologers claim they can tell a person’s intelligence from his or her horoscope. But twenty-seven astrologers failed to perform better than chance when given forty horoscopes of intellectually bright subjects and mentally handicapped subjects. Skeptical Inquirer, Vol. 37 (2). https://go.gale.com/ps/i.do?id=GALE%7CA320423984&sid=googleScholar&v=2.1&it=r&linkaccess=abs&issn=01946730&p=AONE&sw=w&userGroupName=oregon_oweb&isGeoAuthType=true&aty=geo

10. Frugoli, A., Parekh, S., & Diaz, G. (2024). Does Western or Chinese Zodiac Sign Predict COVID Infections and Death? Cureus Vol. 16 (3). https://www.proquest.com/openview/280fad910c7636c8a3b95eeb52e05554/1?pq-origsite=gscholar&cbl=2045583

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