“Never again,” said American psychologist Vernon E. Clark, “will it be possible to dismiss the astrological technique as a vague, spooky and mystical business, or as the plaything of undisciplined psychics, or as merely the profitable device of unscrupulous quacks.”
The late Dr. Clark believed himself to be on a roll. Over a two-year period between 1959 and 1961 the Baltimore, Md., psychologist had completed three different statistical tests designed to see if astrologers could correctly match individual birth charts with their rightful owners in blind controlled tests. In each test certain information was masked or kept from the researcher to reduce or eliminate bias.
Clark’s matching experiments demonstrated that astrologers could, with statistical significance, identify the professions of test subjects based solely on astrologically indicated talents, capabilities and proclivities. He also showed that astrologers were able to match birth charts with life stories and did equally well when identifying cerebral palsy victims based solely on astrological indications.
In each of the Clark experiments astrologers compared and paired the birth charts of real individuals with the bogus, made up birth maps for imaginary people residing in control groups. In each instance there was a 50-50 chance the astrologers would make the correct call, but they did much better.
Clark reported that in each of the three tests he conducted the odds were statistically significant at 100 to one against the likelihood the results occurred by chance. Getting this outcome for all three tests was an impressive accomplishment at the time and encouraged him to conclude:
“Those who, out of prejudice, wish to do so (question the outcomes) will have to remain silent or repeat these experiments for themselves.”
Circling the Wagons
As it turned out, astrology’s critics could find nothing to fault with the statistical methods used by Clark and his associates but refused to fall silent. Instead, they circled the wagons around the fiction that astrologers participating in the tests used extra sensory perception (ESP), not astrology, to produce the reported results.
The idea that the astrological premise cannot possibly be true is deeply ingrained in the minds of many deniers who believe astrology is not a plausible explanation for anything in the material world. Ergo, any matching study that produces a favorable result for astrology must necessarily be flawed in some way.
University of California (Berkley) graduate student Shawn Carlson clearly felt this way. Egged on by leaders of the CISCOP skeptical organization (now CSI), Carlson set out to trash an earlier matching study that showed individual subjects were able to identify their own astrologically prepared personality profile when presented with multiple options. This study was conducted by a group of Chicago astrologers led by astrologer Neil Marbell. The group started working on the study in 1976 and announced a successful outcome at a press conference years later in 1981.
Originally, the study was sponsored by the CSICOP skeptics but the cold-footed leaders of the organization pulled out for reasons that remain unexplained. Marbell completed the study with statisticians at the University of Wisconsin and other volunteers.
Carlson’s much ballyhooed matching study was all about discrediting the successful results claimed for the earlier study. In his Double Blind Study of Astrology, Carlson asked participants to complete multiple tasks. Specifically, astrologers were asked to match the birth charts of test subjects with psychological profiles prepared using California Psychological Inventory (CPI) guidelines. Test subjects, mostly students, were asked to see if they could pick their own CPI profile from a group that included their own plus profiles prepared for two other study participants. Still another test sought to determine if the subjects would fare any better if the profiles were prepared by professional astrologers based on astrological indications.
Results of Carson’s research were published in the prestigious science journal Nature in 1986, and were subsequently challenged by the late Suitbert Ertel of the GM Institute of Psychology in Gottingen, Germany. Carlson’s test methods also were independently challenged by psychologists Hans Eysenck and Joseph Vidmar.
Ertel’s critical assessment of the Carlson study was published in the Journal of Scientific Research (JSE). It raised fairness issues, questioned sample size, identified sampling errors, found flaws with the methodology used, and noted that careless data handling may have tainted the results. Ertel also questioned Carlson’s piecemeal approach to statistical analysis and refuted his claim that the study “made a strong case against natal astrology as practiced by reputable astrologers.”
The tests involving student volunteers were especially suspect. Ertel noted that half of the data ratings were so poor they could not be analyzed, and the half that could be analyzed was not carefully completed. More than one in three students failed to complete their assignments. And the students were unable to identify their own CPI profile from a choice of three to a significant level.
On the other hand, the astrologers performed considerably better than Carlson reported. Based on a reanalysis of the data, Ertel confirmed that the astrologers were able to select the correct profile as either their first or second choice at a rate significantly better than expected by chance. And, in a separate test, they were able to identify which profile was the poorest fit, a finding that also contradicted Carlson’s original claim.
Sorting Conflicting Claims
Conflicting claims can be difficult to sort. What should cheer astrologers everywhere is the growing body of solid physical evidence is less easy for deniers to refute. More efficient computer systems and software programs are revolutionizing the ways astrologers are demonstrating the validity of astrological truth claims in the current era. There’s even an astrological research protocol that effectively lays the ESP argument to rest.
Vernon Clark was obviously a few steps ahead of himself when he suggested it will never again be possible to dismiss the astrological technique as a vague, spooky and mystical business or as the plaything of undisciplined psychics. But his thoughts were clearly racing ahead in the right direction.