ARE PERSONALITY-DIFFERENCES BETWEEN TWINS PREDICTED BY ASTROLOGY

In Fuzeau-Braesch [Astrologie: La Preuve par Deux (1992a) and Personal ity and Individual Differences 13, 1135-1144 (1992b)] the parents of 2 38 pairs of twins matched brief astrological descriptions with their t wins' personalities and achieved 68.5% hits, very significantly better than the 50% expected by chance. The author concluded that astrology may be a ''new element in differentiating personality within a pair of twins.'' But we found reasons for doubt: her result is incompatible w ith previous findings, the disattenuated effect size is too high, the interval between births does not increase with increasing personality difference as required by her hypothesis, the astrological description s frequently differ from those prescribed by her supposedly objective rules, and the hit rate does not replicate. We then attempted to find an explanation for her results: we found evidence of artifacts in her reported data due to response set and stereotypes, and we found discre pancies between the reported data and the original data. Our re-analys is of the original data showed no significant deviation from chance. W e conclude that an astrological explanation of Fuzeau-Braesch's result s is unwarranted. The stereotype bias uncovered by us deserves to be a dded to the general list of human judgement biases. Copyright (C) 1996 Elsevier Science Ltd.