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116: What influences you

116-horoscopes

Do you put stock in horoscopes?

Show notes and links:
How Are Horoscopes Still a Thing? (Smithsonian Magazine)
The Barnum Effect (Fullerton Department of Psychology)
Harmless fun? Horoscopes may be bad for you, study suggests (The Telegraph)
Written in the stars (The Guardian)
Comprehensive study of ‘time twins’ debunks astrology (The Washington Times)


Full episode text

Around 1937, British astrologer R.H. Naylor started publishing astrological predictions for everyday people, on the basis of sun signs, also known as star signs. This was one of the first incarnations of the modern newspaper horoscope. This was an outgrowth of the common practice of asking astrologers to offer their opinion on individuals often showing up in society pages.

Depending on who you ask, somewhere between 12 and 37 percent of Americans read their horoscope daily. A 2009 Harris poll reported that 26 percent of Americans self-report as believing in astrology.

But believing in something doesn’t make it scientifically supported. One of the challenges of astrology is designing a study that rigorously tests the personality traits and the accuracy of predictions. One study in 2003, however, attempted to do just that. Researchers tracked 2,000 babies whom were all “time twins” – born in the same few weeks in a similar place – for several decades. More than 100 different characteristics were measured, and researchers found no similarities that sun-sign astrology would predict to be the case.

Not all scientists agree – Percy Seymor argues in The Scientific Proof of Astrology that shifting magnetic fields do have an impact on fetal development. Dr. Mike Hapgood, quoted in The Guardian responding to this book, agreed that we don’t well understand how these fields impact human behavior.

In pointing to why, despite the lack of solid evidence, so many people base so much on horoscopes, two effects are most often mentioned. The Barnum effect, which explains that when individuals encounter descriptions of themselves, they tend to be more willing to believe those descriptions. There’s also the 1948 Forer study of self-validation, where students rated generic descriptions 4.26 on a scale of 1-5 as being “accurate” because they had previously taken a personality test.