A 1915 medical illustration showing the “stages of mental development.” This 1915 chart, titled Steps in Mental Development, appeared in the report Mental Defe

A 1915 medical illustration showing the “stages of mental development.” This 1915 chart, titled Steps in Mental Development, appeared in the report Mental Defectives in Virginia and reflected the era’s flawed and pseudoscientific views of intellectual disability. It divided individuals into five ri…