The Barnum Effect is named after P.T. Barnum, who is known to have the ability to separate gullible people from their money. Barnum once said "there's a sucker born every minute." The Barnum Effect, according to Chapter 14 of the book, is described as "the tendency of people to accept high base rate descriptions". High base rate descriptions refers to descriptions that apply to almost everyone. This is why it is named the Barnum Effect, or also known as the P.T. Barnum Effect. People are too gullible. Examples of Barnum Effect descriptions would be....
-You have a great need for other people to like and admire you.
-You have a great deal of unused capacity, which you have not turned to your advantage
-At times you have serious doubts as to whether you have made the right decision or done the right thing.
The Barnum Effect accounts for the popularity of horoscopes, crystal balls, palmistry, tea leaf, and tarot card readings. However, there's no evidence for their validity. In 1983, Susan Blackmore did a study that resulted in clients' inability to pick out their own tarot card readings from nine other readings. Each card contained general statements that apply to everyone. This result also applies to horoscopes. A study done by Dean in 1987 showed people couldn't pick out their own horoscope from other ones at better-than-chance levels. Astrology makes extraordinary claims, but there is no evidence for these claims. People fall prey to confirmation bias, and once they read the horoscope, they believe it fits them well. If everyone read all of the horoscopes, they would realize that each one applies to the just as much as the others. Due to studies done by people such as Blackmore and Dean, it's obvious that horoscopes, tarot card readings, among others are all not valid and none of them can confirm what they are said to confirm, which means their not valid.
Chapter 14 of the book