Belief in Astrology A Test of the Barnum Effect i CHRISTOPHER C. FRENCH, MANDY FOWLER, KATY MCCARTHY, and DEBBIE PEERS here is no empirical support for the claims of traditional astrological theory (see Culver Tand Ianna 1988; Dean and Mather 1977; Eysenck and Nias 1982; Gauquelin 1979; Jerome 1977; Kelly 1979; Startup 1984). Despite this, the level of belief in astrology in the general population is high and shows no sign of declining. Most people who have their horo- scopes cast perceive those horoscopes to be an accurate description of their personalities. Why should this be? The simple Several factors have been suggested as Barnum effect playing a role in forming and maintaining a belief in the validity of horoscopes (Dean 1987; Tyson provides the best 1982). One of the most well known is the so- explanation for called Barnum effect, the tendency for people to accept vague, ambiguous, and general state- belief in astrology, ments as descriptive of their unique personal- regardless of the ities. professed level of There are two differing reasons given in the literature for naming this inclination to believe belief. "the Barnum effect," although both are based on quotations from P. T. Barnum. The first is that the famous circus-owner maintained that his secret of success was always to have a little something for everyone. Likewise, the typical astrological personality profile consists of a collection of statements carefully selected to enable everyone to see something of themselves in the description. The second, more cynical reason is that Barnum's most infamous phrase was, of course, "There's a sucker born every minute." The best way to appreciate the force of the 166 SKEPTICAL INQUIRER, Vol. 15 Barnum effect is to actually read a of research has been done on the typical Barnum profile. Try it: psychological factors that influence the Barnum effect. Although a You have a great need for other detailed review of these studies is people to like you and admire you. beyond the scope of this discussion You have a tendency to be critical (see Dickson and Kelly 1985; Furnham of yourself. You have a great deal of unused capacity which you have and Schofield 1987; Snyder, Shenkel, not used to your advantage. While and Lowery 1977), it is clear that the you have some personality weak- effect is an important factor in the nesses, you are generally able to acceptance of horoscopes (see, e.g., compensate for them. Your sexual studies by Rosen 1975; Snyder 1974; adjustment has presented problems Snyder, Larsen, and Bloom 1976). for you. Disciplined and self- However, not all statements in controlled outside, you tend to be horoscopes are Barnum-type state- worrisome and insecure inside. At ments. For example, the typical times you have serious doubts as to whether you have made the right "Aries" is said to be bold, energetic, decision or done the right thing. You assertive, selfish, insensitive, and prefer a certain amount of change aggressive. Surely, not everyone and variety and become dissatisfied would see themselves as fitting this when hemmed in by restrictions and description. But, as Sundberg (1955) limitations. You pride yourself on pointed out, Barnum profiles consist being an independent thinker and of a variety of statements: do not accept others' statements without satisfactory proof. You Vague, e.g., "You enjoy a certain have found it unwise to be too frank amount of change and variety in in revealing yourself to others. At life"; double-headed, e.g., "You are times you are extraverted, affable generally cheerful and optimistic and sociable, while at other times but get depressed at times"; modal you are introverted, wary and characteristics of the subject's reserved. Some of your aspirations group, e.g., "You find that study is tend to be pretty unrealistic. Secur- not always easy"; favorable, e.g., ity is one of your major goals in life. "You are forceful and well-liked by others." Typically, a naive subject reading the personality description above would The typical horoscope is a mix of be impressed by its accuracy if told general statements and rather more that the description was based upon specific ones. People tend to be his or her horoscope. This profile was impressed by the specific details that actually first used in a study some 40 appear to fit (and pay less attention years ago (Forer 1949), but its appeal to those that do not), while the general is as strong today as it was then. Barnum-type statements provide It is important to realize that the readily acceptable "padding." Barnum effect does not apply only to It seemed possible to us that personality descriptions supposedly different psychological mechanisms based upon horoscopes. The effect is might be required to explain the found if the profile is said to be based formation and maintenance of belief upon any form of personality assess- in strong believers compared with ment, including palmistry, objective moderate believers. One possibility psychological tests, projective tests, was suggested by Goldberg (1979). personal interview, graphology, or Some "Virgos" actually will, by chance Tarot cards. A considerable amount alone, have the personality character- Winter 1991 167 istics typically associated with that other hand, would not be as inclined sun-sign, and similarly for all of the to look for the typical profile because other sun-signs. Such people will be they are unlikely to possess detailed constantly amazed at the accuracy of knowledge of typical sun-sign profiles. horoscopes based upon this informa- Moderate believers are likely to be tion and are far more likely to take more impressed by the carefully their interest in the subject further selected Barnum-type statements and than those who feel that the person- to be less able to distinguish between ality descriptions typical for their sun- genuine and false horoscopes. All of signs are not appropriate—such as a these effects would be relative, of timid "Aries." The believer is likely to course, since even moderate believers buy popular books on astrology and may have some knowledge of their be attracted to others with an interest typical sun-sign profiles. in astrology, and some of these others An alternative hypothesis main- will by coincidence be typical examples tains simply that the Barnum effect of their sun-signs, providing for the will be equally strong for everyone believer seemingly incontrovertible and that some other (unspecified) fac- proof that astrology is valid. We shall tor is required to account for differ- henceforth refer to this model as the ences in belief between strong and "Coincidence Hypothesis," as the moderate believers (see Dean 1987, original match between the typical for possibilities). In this case, one sun-sign profile and the individual's would argue that the effectiveness of personality is totally coincidental. horoscopes is due largely to the The scenario above, although spec- Barnum effect and that genuine horo- ulative, seemed plausible to us and led scopes are effective only to the extent to some testable hypotheses. If differ- that they incidentally capitalize on the ent mechanisms are responsible for effect. We would predict a different producing different levels of belief in pattern of results on the basis of this the way described, then we would hypothesis. Both genuine and predict that strong believers would Barnum-type horoscopes would be show less acceptance of the Barnum- judged as accurate by all believers, but type profile than moderate believers, the Barnum profile ought to be judged for the following reasons. Strong as more accurate, as the careful believers would be likely to have more selection of statements would maxi- knowledge of the typical characteris- mize the effect. Furthermore, there tics associated with sun-signs, partic- would be no difference in the per- ularly the believers' own signs. ceived accuracy of genuine and false Therefore they would be more horoscopes. We shall refer to this impressed by reading a description hypothesis simply as the "Barnum that corresponded to this typical Hypothesis." pattern and contained reference to A third hypothesis, which has specific expected traits than by the already been thoroughly discredited, more general Barnum-type descrip- can also be outlined. The "Astrological tion. Furthermore, strong believers Hypothesis" would maintain that the would rate horoscopes cast on the position of the stars and planets at basis of their birth details (henceforth birth really does influence the forma- referred to as "genuine" horoscopes) tion of personality as outlined in as more accurate than randomly traditional astrology. If this were so, selected horoscopes ("false" horo- everyone, regardless of degree of scopes). Moderate believers, on the belief, ought to rate genuine horo- 168 SKEPTICAL INQUIRER, Vol. 15 scopes as more accurate than either scope on the basis of the date of birth false or Barnum-type horoscopes. only and produces a profile consisting In order to test these hypotheses, of a dozen statements (a typical data were collected from 52 subjects, example of the output is shown in most of whom were attending a sixth- Figure 1). The program was modified form college. Ages ranged from 16 to to produce output consisting solely of 35, with a mean age of 18. Thirty- the personality profile, omitting the five of the subjects were female. astrological data upon which the Subjects were told that the study was interpretation was based. The false an assessment of three different com- horoscopes were randomly selected puter programs for casting horo- horoscopes from the pool of genuine scopes and were initially asked to horoscopes, so that the two pools were provide information on their date, in fact identical. The Barnum horo- time, and place of birth as well as scope was the same as the one pres- information relating to their belief in ented earlier except that one sentence and knowledge of astrology.