The Validity of Astrology

Most scientists belong here Do not believe in astrology

Overview: What is astrology? “Fairest test” Problems Countering potential criticisms New criticisms and changes New study (then) Results of the new study Final point Conclusion

What is Astrology? It’s claim: “The psychological attributes and personal destinies of individual human beings are related to the positions of heavenly bodies at the moment of each person’s birth.”

“Fairest test” of Astrology: To test the reliability of predictions made by qualified astrologers based on global interpretations of complete horoscopes

Problems: Predict single dimensions of personal information (not the full pattern of the person’s life experience/ personal characteristics) small sample size No blinding Not planned closely with astrologers (vulnerable to criticism that test is not a fair representation)

Countering Potential Criticisms: Previously, not planned closely with astrologers Astrologers and scientists design a test of the hypothesis together

Study consisted of 2 parts: Part 1 Part 2 Non- astrologer subjects have equal difficulty in choosing a horoscopic interpretation (out of 3) that best describe themselves and in choosing from 3 profiles from the California Personality Inventory (CPI) that best describe themselves No clear conclusion on reliability of personality descriptions obtained from astrology Astrologer subjects were not able to choose 1 out of 3 CPI profiles o match test subjects whom they have the horoscope Strong case against natal astrology

New Criticisms and Changes: CPI may not include information astrologers need to match to horoscope successfully Astrologers list personal information they need to match accurately Previous studies of astrology limited to see if astrologers can predict personality traits Astrology often used to predict whether an event occur or when it’ll occur Astrologers asked for information on significant events in test subject’s lives Changes made to present study: Changes made to present study:

New Study (then): X 23 6 Astrologers Practiced astrology before Control: Graduate in clinical psychology Native born Americans; aged 30 / 31 Blinded Record choices on an answer form

Astrologers then match the personal information to corresponding birth information of the 23 people

Results: Correct first choice attempts ranged from 0 to 3 astrologers Control managed to get 3 correct matches Generally, astrologers were certain in their predictions Mean confidence rating = 73.5% Between astrologers, Pearson correlation between number of correct predictions and mean self-rated certainty was not significant r = 0.03

Results: For those who had at least 1 correct match, confidence ratings for both correct and incorrect predictions were not significantly different When second choices are considered, astrologers still did not do better than chance But control achieved more matches than any astrologer

So far, results are…

If astrology have a coherent system of analysis and prediction, its practitioners should be able to apply the method in a dependable and convergent manner If predictions are wrong, they should at least “show a pattern of internal consistency or interastrologeragreement” HOWEVER…

Failure to demonstrate interjudge reliability / convergence Pairwise comparisons between astrologer’s forecast for the 23 people obtained a mean of only 1.4 agreements Across 15 pairwise comparisons among 6 astrologers, no. of agreements range from 0 to 3 Failure to demonstrate interjudge reliability / convergence Each astrologer use his own system to predict

What Does This Mean? On average, each horoscope can be confidently prescribed to at least 6 different people BUT horoscope is VERYY complex, provide very differing “predictions” about a person Hence, astrologers need to emphasise some aspects of the chart and downplay others What could be the reason for the results obtained: Numerous possible combinations that result from placing different weightings to different aspects of the chart

Final Point: Experimental task was much simpler compared to counselling practice of astrologers In practice, each astrologer must use birth information to “select” the right interpretation that matches the individual from so many possibilities, not only 23 like in the experiment If they cannot perform a simple task accurately, how can they accurately perform a more complex one?

Conclusion: Astrology?

Reference: Mcgrew, J.H. and Mcfall, R.M. (1990). A scientific inquiry into the validity of astrology. Journal of Scientific Exploration, vol 4, No 1, pp. 75-83.