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