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Skeptical Studies in Astrology

Figure 1 Natal Chart

Astrologers who claim they can analyze a person's character and predict a person's life course just by reading the "stars" are fooling the public and themselves, University of California researcher Shawn Carlson has concluded in a unique double-blind test of astrology published in Nature (December 5, 1985). The controlled study was designed specifically to test whether astrologers can do what they say they can do. Carlson, a researcher at UC's Lawerence Berkeley Laboratory, found astrologers had no special ability to interpret personality from astrological readings. Astrologers also performed much worse in the test than they predicted they would, according to Carlson.

The study refutes astrologers' assertions that they can solve clients' personal problems by reading "natal charts," individual horoscopes cast according to the person's date, time, and place of birth. "It is more likely that when sitting face to face with a client, astrologers read clients' needs, hopes, and doubts from their body language," said Carlson, who is also a doctoral canidate in physics at UCLA and a professional magician who has himself performed "psychic ability" demonstrations.

Carlson's research involved 30 American and European astrologers considered by their peers to be among the best practitioners of their art.

The study was designed specifically to test astrology as astrologers define it. Astrologers frequently claim that previous tests by scientists have been based on scientists' misconceptions about astrology.

To check astrologers' claims that they can tell from natal charts what people are really like and how they will fare in life. Carlson asked astrologers to interpret natal charts for 116 unseen "clients." In the test, astrologers were allowed no face-to-face contact with their clients.

For each client's chart, astrologers were provided three anonymous personality profiles - one from the client and two others chosen at random - and asked to choose the one that best matched the natal chart. All personality profles came from real people and were compiled using questionnaires known as the California Personality Inventory (CPI). The CPI, a widely used and scientifically accepted personality test, measures traits like aggressiveness, dominanace, and femininity from a long series of multiple-choice questions.

Figure 2 Graph showing percentage correct vs. Weight for astrologers' first-place choices in CPI-profile natal-chart matching. The best linear fit is consistent with the scientifically predicted line of zero slope. No significant tendency is shown for the astrologers to be more correct when they rate a CPI as highly matching a natal chart.

According to Carlson, the study strenuously attempted to avoid anti-astrology bias by making sure astrologers were familiar with the CPI and by incorporating many of the astrologers' suggestions. At the same time, to prevent testers from inadvertently helping astrologers during the test, the project was designed as a double-blind study where neither astrologers nor testers knew any of the answers to experimental questions.

Despite astrologers' claims, Carlson found those in the study could correctly match only one of every three natal charts with the proper personality profile - the very proportion predicted by chance.

In addition, astrologers in the study fell far short of their own prediction that they would correctly match one of every two natal charts provided. Even when astrologers expressed strong confidence in a particular match, they were no more likely to be correct, Carlson found.

Concludes Carlson:

We are now in a position to argue a surprisingly strong case against natal astrology as practiced by reputable astrologers. Great pains were taken to insure that the experiment was unbiased and to make sure that astrology was given every reasonable chance to succeed. It failed. Despite the fact that we worked with some of the best astrologers in the country, recommended by the advising astrologers for their expertise in astrology and in their ability to use the CPI, despite the fact that every reasonable suggestion made by advising astrologers was worked into the experiment, despite the fact that the astrologers approved the design and predicted 50% as the "minimum" effect they would expect to see, astrology failed to perform at a level better than chance. Tested using double-blind methods, the astrologers' predictions proved wrong. Their predicted connection between the positions of the planets and other astronomical objects at the time of birth and the personalities of test subjects did not exist. The experiment clearly refutes the astrological hypothesis.

"A lot of people believe in astrology because they think they have seen it work," Carlson observed. He believes many astrologers are successful at their art because they draw important clues about clients' personalities and lifestyles from facial expressions, body language, and conscious or unconscious verbal responses. "When magicians use the same technique, they call it 'cold reading,' " said Carlson.

Based on his scientific findings, Carlson suggests many people would 'do better to spend their money on trained psychology counselors. However, he disagrees with those who would like to see astrology outlawed. "People believed in astrology for thousands of years and no doubt will continue to do so no matter what scientists discover. They are entitled to their beliefs, but they should know that there is no factual evidence on which to base them."

"The astrologists' reactions so far have been pretty much what I expected," Carlson told the SKEPTICAL INQUIRER. "The astrologists whom I didn't test are saying that the test was not fair because I did not test them. Of course, if I had tested them instead, and they had failed, then the astrologers I actually tested would now be saying that the test was not fair because I did not test them.

"I attended an NCGR party - I was the only non-astrologer in the house - to discuss the research shortly after it was published. The discussion was, to put it politely, energetic. I have not yet received a serious scientific challenge to the paper." The newsletter of the American Federation of Astrologers Network published a response in January (1986). "I was very disappointed to see that it largely consists of personal attacks," Carlson said. He said its few substantive criticisms are attributable to ignorance of his experiment, of the CPI, and of basic scientific methodology.

Carlson's study was supported by Richard Muller, professor of physics at UC Berkeley, and paid for by a general congressional research award.


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