47 To Catch a Thief: The Psychology of Fingerprints

What were some of the earliest fruitful psychology studies?

In the late 1800s one psychologist, Sir Francis Galton, became obsessed with measurement.  In 1880, a physician named Henry Faulds asked for help in documenting some important properties of fingerprints as he suspected but did not know how to demonstrate that no two people have the same fingerprints.

Interested in fingerprints for years, Francis Galton embarked on a series of empirical studies. He was the first to apply statistical methods to the study of human differences. Using statistical probability he demonstrated that no two people have the same fingerprints. In addition, he found a person’s fingerprints remain largely unchanged over the course of a lifetime.  Galton also developed the first system for classifying and identifying fingerprints as described in his book, Fingerprints, published 1892.

Law enforcement experts realized that Galton’s discoveries made it possible to use fingerprints as a highly reliable way to identify people, including people who did not wish to be identified!  In 1892, an Argentine police officer used fingerprints to prove that a woman had murdered her two sons. By 1905, law enforcement agencies in both England and the U.S. were routinely using fingerprints in criminal investigations.