Skeptical Studies in
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
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 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
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,
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,' "
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