Why Do People Believe in Astrology? The Psychology of a Horoscope That Fits
By the BrainSnail editorial team. How these articles are written and checked, and how to tell us when one is wrong.
In 1948 a psychology lecturer gave his students a personality analysis, told each that it had been written for them from a test they had taken, and asked them to rate its accuracy. The average score was 4.3 out of 5. Every student had received the same paragraph, assembled from a newsstand astrology book. The experiment has been repeated with horoscopes, palm readings and personality tests for seventy years with the same result, and it explains most of why a system of prediction that has never passed a test is consulted by a third of adults in some countries and treated as a matter of identity by many of them.
The claim
Astrology holds that the positions of the Sun, Moon and planets against the zodiac at the moment of birth shape a person's character and fate. It arose in Babylon, where the planets were gods and their movements omens for the state, passed to the Greeks, who turned it into a system for individuals around 200 BC, and was serious science for two thousand years; Kepler cast horoscopes for a living. It lost the astronomers in the seventeenth century, when the Earth stopped being the centre of anything, and it lost its physical basis when the forces involved were measured: the gravitational pull of the midwife on a newborn is greater than that of Mars. The Sun-sign column, which reduces the whole apparatus to twelve types and appeared in a British newspaper in 1930, is what most people now mean by it.
The tests
Astrology makes claims that can be checked, and they have been:
- •Shawn Carlson in 1985 had 28 astrologers match natal charts to personality profiles of real people; they chose the right one at exactly the rate chance predicts, and the study was published in Nature
- •Studies of time twins, people born within minutes of each other, find no more similarity in personality, intelligence, occupation or life events than between strangers; the largest followed 2,000 people born in London in one week of 1958
- •Marriage records of millions of couples show no tendency for compatible signs to marry or incompatible ones to divorce
- •Astrologers given the same chart produce different readings, and given different charts produce readings their clients rate as equally accurate
- •The one apparent success, the French statistician Michel Gauquelin's finding that champion athletes were born more often when Mars was rising, dissolved when the sample was cleaned of his own selection
Why it feels right
The Barnum effect, named for the showman's remark about having something for everyone, is the tendency to accept vague, general and mostly flattering statements as accurate descriptions of oneself. A horoscope that says you have a great deal of unused capacity, that you are sometimes extroverted and sometimes reserved, and that you value the good opinion of others, describes everyone and is read as describing the reader. The effect is strongest when the statement is believed to be personalised, when the source seems authoritative, and when the content is positive, and it is reinforced by confirmation bias: the days the horoscope fits are remembered and the days it does not are forgotten. A sign's description also shapes the self: people who know their sign's traits rate themselves as having them more than people who do not, and the correlation between sign and personality that shows up in some surveys vanishes among those who are unaware of what their sign is supposed to be like.
What it supplies
Belief persists because astrology does things that have nothing to do with prediction. It offers a vocabulary for talking about personality and relationships that is richer than most people otherwise have, and a way of raising the subject of oneself without seeming to; a conversation about whether one is a typical Scorpio is a conversation about who one is. It offers a sense of order in an uncertain life, and studies find that interest in astrology rises with personal and economic stress, as it did in the 1930s and after 2008. It offers permission, in the form of an external reason for a decision already leaning one way. And it is, for most readers, entertainment held at arm's length; surveys that ask whether astrology is scientific get far fewer yeses than surveys that ask whether people read their horoscope.
Does it matter
Mostly it is harmless, and the psychologists who study it tend to be more interested in what it reveals about belief than in stamping it out. The harm is at the margins: money spent on readings by the anxious, medical or financial decisions deferred to a chart, and the general habit of taking a good-feeling account over a tested one, which is the habit that other and more expensive beliefs exploit. The instructive fact is that knowing about the Barnum effect does not switch it off; the students who were shown that they had all received the same paragraph reported, in follow-up studies, that theirs had nonetheless been unusually accurate. The mind that reads a horoscope is the same one that reads everything else, and astrology is simply where its workings are easiest to see.
The takeaway
Astrology has failed every controlled test, from matching charts to people to comparing time twins and marriage records, and has no physical mechanism, yet it is read by hundreds of millions because of the Barnum effect, by which vague and flattering statements are accepted as personal, reinforced by confirmation bias and by people growing into their sign's description. It persists because it supplies a language for personality, a feeling of order under stress, and a licence for decisions, which are wants that a correct account of the planets does not meet.