Emma Wolverton, also known as Deborah Kallikak, lived her entire life in an institution in New Jersey after psychologist Henry Goddard classified her as feeble-minded. He also wrote a book about Wolverton and her family that psychiatrists previously used to show that intellectual disability is hereditary. At the time, researchers in the psychology field, including Goddard, were working to understand differences in people’s intellectual abilities. They used the term feeble-minded to refer to those they described as having lower intellectual functioning. While Wolverton spent nearly her entire life living and working in institutions for the feeble-minded, more recent investigations of her life show she was not what is now considered intellectually disabled. Wolverton’s involvement in Goddard’s research as Deborah Kallikak influenced twentieth century ideas around the heritability and treatment of those with disabilities.

Lewis Madison Terman was a researcher and university professor who studied educational psychology and advocated for eugenics in the United States during the early twentieth century. The US eugenics movement, which Terman supported, was a collection of scientific research and social programs that aimed to improve human populations through control over human reproduction. One area many eugenicists studied was human intelligence as a means of determining how “desirable” a person may be. During the 1910s, while working at Stanford University in Palo Alto, California, Terman helped devise the Stanford-Binet scale for intelligence testing. As of 2024, the Stanford-Binet test is one of the main methods for providing individual intelligence quotient, or IQ, scores. In addition to the Stanford-Binet scale, Terman promoted the idea that individuals had fixed and inherited capacities for intelligence. Through both his development of a widely used method for measuring human intelligence and his promotion of the idea of intelligence as hereditary, Terman supported widespread social efforts to control human reproduction in the US during the twentieth century.