There are many subsets of psychology. No doubt one of the most fascinating is forensic psychology. Forensic psychology is basically the intersection of psychology and the legal system.

It’s quite a broad field. Psychologists work in a variety of settings, including police departments, prisons, courts and juvenile detention centers. And they do everything from assessing whether an incarcerated individual is ready for parole to advising attorneys on jury selection to serving as experts on the stand to counseling cops and their spouses to creating treatment programs for offenders. Most are trained as clinical or counseling psychologists.

So how did this interesting specialty emerge and expand? Here’s a brief look at the history of forensic psychology.

The Birth of Forensic Psychology

The first research in forensic psychology explored the psychology of testimony. James McKeen Cattell conducted one of these early studies in 1893 at Columbia University.

In his informal study, he asked 56 college students a series of questions. Among the four questions were: Do chestnut or oak trees lose their leaves earlier in autumn? What was the weather like one week ago today? He also asked students to rate their confidence.

Findings revealed that confidence didn’t equal correctness. Some students were confident regardless of whether their answers were correct, while others were always insecure, even when they provided the right answer.

The level of accuracy also was surprising. For instance, for the weather question, students gave a wide range of responses, which were equally distributed by the types of weather possible that month.

Cattell’s research ignited the interests of other psychologists. For example, Joseph Jastrow at the University of Wisconsin replicated Cattell’s study and found similar results.

In 1901, William Stern collaborated with a criminologist on an interesting experiment that further showed the level of inaccuracy in eyewitness accounts. The researchers staged a phony argument in a law class, which culminated in one of the students drawing a revolver. At that point, the professor intervened and stopped the fight.

Then students were asked to provide written and oral reports of what happened. Findings revealed that each student made anywhere from four to 12 errors. The inaccuracies peaked with the second half of the squabble, when tension was highest. So they cautiously concluded that emotions reduced the accuracy of recall.

Stern became very active in the psychology of testimony and even established the first journal to explore the subject, called Contributions to the Psychology of Testimony. (It was later replaced by the Journal of Applied Psychology.)

Based on his research, Stern made a variety of conclusions, including: suggestive questions could compromise the accuracy of eyewitness reports; there are major differences between adult and child witnesses; the events that occur between the original event and its recall can dramatically affect memory; and lineups aren’t helpful unless they’re matched for age and appearance.

Psychologists also began testifying in court as expert witnesses. The earliest example of this was in Germany. In 1896, Albert von Schrenck-Notzing provided an opinion testimony in the trial of a man accused of murdering three women. The case received a lot of press coverage. According to Schrenck-Notzing, the sensationalist pretrial coverage clouded witnesses’ memories because they were unable to separate their own original accounts with the press reports. He substantiated his opinion with psychological research.

In 1906, a defense attorney asked German psychologist Hugo Munsterberg to review his convicted client’s investigation and trial records. The client had confessed to murder but then recanted. Munsterberg believed that the man, who was mentally disabled, was probably innocent, and he was skeptical about how the confession was obtained. Unfortunately, the judge refused to review the case and the man was hanged. The judge also was furious with Munsterberg for thinking that he had expertise in this case.

This was one of the events that prompted Munsterberg to publish On the Witness Stand in 1908. In it, he explained that psychology was vital in the courtroom, how suggestion could create false memories and why eyewitness testimony was often unreliable.

In 1922, William Marston, a student of Munsterberg’s, was appointed the first professor of legal psychology at American University. (By the way, you might remember Marston as the creator of Wonder Woman.) He discovered a link between lying and a person’s blood pressure, which would become the basis for the polygraph.

Marston’s testimony in Frye v. U.S. in 1923 also set the standard of accepting expert testimony. He, along with other psychologists, worked as one of the first psychological consultants to the criminal justice department. Plus, he conducted a variety of studies on the jury system and testimony accuracy.

During the World Wars, forensic psychology was largely stagnant. But in the 1940s and 1950s, psychologists began regularly testifying in courts as experts on a range of psychological topics. For instance, in 1954, various psychologists testified in Brown v. Board of Education, and played an integral role in the court’s decision.

Other interesting events contributed to forensic psychology’s development. For instance, in 1917, Lewis Terman was the first psychologist to use mental tests to screen police offers. Later, psychologists would use personality assessments for screening. (See here for a fascinating article on Terman and his research.)

In the early 20th century, psychologists tested prisoners for “feeblemindedness,” which was believed to lead to a lifetime of criminal behavior.

During this time, psychologists also worked on classifying prisoners. In the 1970s, one psychologist identified 10 types of inmates, categories that were used to assign prisoners to jobs, programs and other placements.