Scientists say judges across the United States fail to keep unreliable psychological and IQ tests from being used as evidence, resulting in junk science in courtrooms. The research says such tests can influence juries and judges whether it’s used in bail hearings or death penalty cases.
Scientists studied hundreds of different tests as part of the study, published in Psychological Science in the Public Interest journal. They found prominent psychological manuals had not reviewed one-third of the tests, and only 40% received a favorable rating.
Validity of psychological tests rarely challenged
While 25% of the tests that were reviewed by the scientists were deemed unreliable, challenges to the validity of tests used during court proceedings happen in less than 3% of all cases, according to the researchers.
Many experts consider this report as highly significant because so many defendants’ fates are tied to the results of psychological tests. The lead researcher says there are too many exams based on junk science and should be filtered out by the courts.
Study identifies most frequently used tests
The researchers’ conclusions came from 876 court cases between 2016 and 2018. The test used most often was the Minnesota Multiphasic Personality Inventory, which is generally viewed as favorable in professional publications.
However, that’s not the case for the second-most used exam, the Rorschach test, also called the inkblot test. That exam was developed in 1921, and while some defend it, many scientists regard it as dangerously subjective and ambiguous.
Previous criticism of psychological tests mostly ignored
The new report is not the first time these tests have been challenged. The National Research Council released a study in 2009, finding that erroneous forensic science may have contributed to the convictions of many innocent people.
That critique called for reforms, but many say only partial progress has been made. Legal experts say judges and lawyers are not proficient on these methods and must rely on the expertise of psychologists. That has prompted many critics to urge those professionals to clean up their own field.