Mentally defective was a term used during much of the twentieth century to describe people with intellectual disabilities.
The Mental Deficiency Act of 1920 established a Mental Deficiency Board to supervise adults and children diagnosed as mentally defective. The Act also established the State Psychological Clinic which provided the diagnosis
The term mentally defective appears in case files kept by the Mental Deficiency Board and the records of the State Psychological Clinic.
Influenced by eugenics, the framers of the Act did not believe that so called mental defectiveness could be cured. However, they did think that, with proper training and supervision, children that received the diagnosis could lead happy lives.
Children diagnosed as mentally defective often did not have an intellectual disability. Challenging behaviour, inadequately managed physical disabilities such as deafness, educational disadvantage, an institutional upbringing, and poverty, neglect or abuse could all lead to this diagnosis.
Prepared by: Caroline Evans
Created: 25 October 2011, Last modified: 5 March 2015