On the basis of a person's natal chart (horoscope cast according to the person's date, time, and place of birth), astrologers claim to be able to analyze that person's character and personality and make predictions about his or her life course. To test the claims of astrology about character analysis, UCLA physicist Shawn Carlson conducted a study involving thirty American and European astrologers considered by their peers to be among the best in the field. To complete the study Carlson selected 116 "clients," who were then given the California Personality Inventory (CPI), a widely used and scientifically accepted test that measures personality traits. The results of the CPI were then used to compile a personality profile for each of the clients. The astrologers were informed about the nature of the CPI, and to prevent any anti-astrology bias, many of their suggestions were incorporated into the study.

The astrologers were then given each client's natal chart together with three personality profiles. One of the profiles matched the client in question, and the other two were chosen at random from a separate batch of personality profiles composed in the same way as the true one. No astrologer was able to confront any client face-to-face, and the study was done on a double-blind basis so that neither the astrologer nor the experimenters knew which profile corresponded with which natal chart. The astrologers predicted that they would be able to match a chart with the correct profile at least 50 percent of the time. However, as it turned out, only one out of three matches was correct-exactly what would be expected by chance. The results of Carlson's study were published in the widely respected scientific journal Nature.

Do you think that Carlson's study tends to disprove the claim that astrology can analyze personality features? Do you think that if the astrologers were allowed to meet the clients face-to-face, the results would have been different? Why? (From "Double-Blind Test of Astrology . . ." in Frazier, 1991.)

Astrologers also claim the ability to make predictions. In 1978, R. N. Hunter and J. S. Durr of the U.S. Geological Survey invited astrologers to submit predictions about earthquakes. Hunter and Durr analyzed 240 predictions made by 27 astrologers and found that their accuracy was worse than would have been the case had they simply guessed. Also, in 1985, G. Chatillon analyzed 30 predictions for North America made by Huguette Hirsig, one of Montreal's most famous astrologers. Only two were found to be correct. Do studies of this sort tend to disprove the claims that astrologers are able to make true predictions?