Mental retardation is a construct with many interpretations. In some periods of history, mental retardation has been referred to as a disease. In other periods it has been thought of as a disability. Often mental retardation has been represented as social deviance. Most modern professionals in the United States adopt the definition published in 1992 by the American Association for Mental Retardation (AAMR). This definition describes mental retardation as neither a disease nor a disability but a functional state with limitations in both intelligence and adaptive skills. People classified as mentally retarded obtain an Intelligence Quotient (IQ) below seventy when tested with an appropriate standardized instrument. They demonstrate difficulties with adaptive skills, and their problems develop before the age of eighteen. The prevalence of mental retardation has been estimated to be under 3 percent of the general population. The majority of individuals with mental retardation need minimal supports and their disability may go undetected in tolerant environments. Some people require more extensive support, including assistance from family members and professionals. The causes of mental retardation are about evenly divided between organic and nonorganic problems. Organic causes are attributed to prenatal difficulties such as metabolic and genetic disorders, perinatal distress including prematurity and birth injury, and childhood diseases and traumas. Nonorganic causes are associated with environmental deprivation. In many cases the etiology is unknown. Treatment usually requires a multidisciplinary approach to provide a variety of supports that people with mental retardation need in order to function adequately in their homes, schools, places of work, and communities.

Although the AAMR definition is widely accepted in the twenty-first century, traditional interpretations of deviance, disability, and disease lie deeply imbedded in Western culture. These interpretations, usually disparaging, have influenced the ways societies have thought about and responded to people with mental retardation. Their roots lie in philosophical debates, religious beliefs, scientific discoveries, and social developments of the past. The historical record reveals the various meanings associated with mental retardation and its analogous conditions, including idiocy, foolishness, feeblemindedness, and mental deficiency. A review of this history depicts the many ways that mental retardation has been and continues to be defined.

The origins of the construct of mental retardation appear in the writings of Greek and Roman philosophers reflecting on the nature of the intellect. Both PLATO and ARISTOTLE associated human value with the ability to reason. They differentiated mankind from other living beings by the quality of the intellect. People who lacked the capacity to reason were considered barely human and therefore socially inferior. Writings attributed to Hippocrates in the late fifth century B.C.E. adopted a physiological explanation. This work localized the intellect in the brain and explained the intellect's function with humoral theories. In the most intelligent individuals properties of heat and moisture balanced. Those who lacked intelligence were thought to possess an excess of moisture and a deficit of warmth. Variations in the speed of the elements also affected the intellect. In their medical treatises, the Hippocratic writers defined healthy states and illness, and introduced the concept of the mean which would serve as a basis in the future identification of people with mental retardation. The Galenists, writing in Rome in the late second century, adopted the Hippocratic theories of the intellect, systematized them, and elaborated on the humoral interpretation. Galen's understanding of the nature of the intellect was adopted by many scientists and philosophers well into the eighteenth century.

The laws of ancient Rome contributed to Western legal systems the concept of clemency for criminals who acted without intention. Linking incompetence with infancy, Romans established the law that punishment for crimes depended on the understanding and intent of the criminal. The principle is central in Western legal systems, although in the United States the problem of competence and mental retardation in criminal cases remains a contentious issue at the beginning of the twenty-first century. Another legal precedent with economic and political implications appeared in medieval England: in the thirteenth century the English king claimed the property of people who were then called idiots who were unable to manage their personal affairs. The intention was to provide guardianship for people thought to be idiots while also enriching the coffers of the king. The law differentiated idiocy from madness and instituted rudimentary assessments to determine competence. In the early modern period English and American colonial laws provided guardianship and welfare relief for people with mental retardation who were without family support. Tests of competence were developed to assess the eligibility of welfare bene-ficiaries and people convicted of capital crimes. Those tests, and the laws in general, extended assistance to some needy people while they also reinforced images of dependency, incompetence, and infantilism.

In the ancient world most people attributed the mysteries they witnessed to pagan gods, and in medieval Europe they ascribed them to the supernatural powers of witches, devils, and magic. Yet Western views were gradually transformed by the infusion of beliefs and practices of the monotheistic religions JUDAISM, Christianity, and ISLAM. All three religions contributed to the modern social ethic as it concerns mental retardation. This ethic was essentially optimistic, for it recognized intrinsic value in humans created in the image of God. It established principles of justice and affirmed charity on behalf of disadvantaged people. In Christian societies, idiocy, as it was known, provided evidence of God's creativity and a manifestation of the diversity of his universe. Furthermore, idiocy could be construed by Christians as a condition of blessed simplicity and innocence. Despite such magnanimity, however, religious belief also served to reinforce images of idiots as childish, dependent individuals, worthy recipients of beneficence, yet helpless and hopelessly afflicted. Indeed, both Catholics and Protestants banned people thought to be idiots from the sacraments, thereby denying salvation. Such contradictory portrayals of mental retardation have persisted throughout the years and are still evident in the twenty-first century.

The work of the English anatomist Thomas Willis (1621-1675) represented the first modern scientific account of idiocy. Willis adopted the view that idiocy constituted a structural defect in the brain that might be inborn or caused by serious illness or injury. He theorized that the condition could be related to the smallness of the brain, and he distinguished between two types of idiots, one more capable than the other. Willis was probably the first to define idiocy as a disease, to speculate on its causes, and to suggest treatments. Like most physicians of his time, however, Willis believed that in most cases idiocy was permanent and incurable.

Physicians continued to explore the functions of the brain throughout the 1800s. Franz Joseph Gall (1758-1828), for example, concluded that the development of specific regions of the brain accounted for variations of intellect. Influenced by Gall's ideas, other physicians developed the system of phrenology, which associated intelligence with the structure of the head. By the 1870s, phrenology was no longer practiced, although for many years it was commonly believed that brain size was related to the intellect. Other theories drew parallels between intelligence and morality. In his 1866 book Mongols, John Langdon Down concluded that congenital idiocy represented atavism, a degeneracy of the race. Soon after the publication in 1859 of Charles Darwin's Onthe Origin of Species, Francis Galton (1822-1911) proposed methods to improve society by selectively breeding the human species. He named this system EUGENICS, a method of social control with profound implications for humanity in the twentieth century. Frustrated with attempts to prove the correlation between intelligence and the structure of the head, ALFRED BINET (1857-1911) set about to develop an alternative system to measure the intellect. With his student Theodore Simon (1873-1961), Binet produced in 1905 the first test of intelligence to identify children with learning difficulties.

Other scientists in nineteenth century Europe were interested in classification systems in order to differentiate idiocy from madness and to define levels of idiocy based on capability. Their purpose, in part, was to separate those people who were considered more suitable for treatment from those considered incurable. The French physician Édouard Séguin (1812-1880) went further than others and developed his own system of classification which included four types of idiocy. Unlike his colleagues, Séguin adopted more optimistic views of people considered least capable. He protested conditions at the Bicêtre, Paris's notorious mental institution, and introduced treatment programs for idiots who were considered unable to profit from instruction. In 1848 he emigrated to the United States, where he continued his work establishing educational programs based on a physiological method.

Séguin's optimistic approach did not last, however, and by the middle of the nineteenth century idiocy acquired once again the meaning of permanent and incurable disability. In the United States schools originally intended for educating children with mental retardation were gradually converted to custodial facilities with the admission of more seriously disabled people and failures in rehabilitation. By the 1920s the eugenics movement had aroused the public's fear of people with mental retardation, who were denounced as morally degenerate. Institutional settings grew in power and size in order to accommodate the growing numbers of individuals with mental retardation who were rejected by society. Although most people continued to be cared for by family members at home with minimal public support, the social abandonment of thousands of people in large public institutions into the 1970s signified an era of pervasive dehumanization and hopelessness.

In response to the failure of public programs in the United States, parents whose children were mentally retarded organized in the mid-1900s to advocate on their behalf. Encouraged by the civil rights movement of the 1960s, parents and their professional allies sought educational opportunities, medical treatment, community living situations, and basic human rights. The concept of normalization coincided with the deinstitutionalization movement in the 1970s to promote services for people with mental retardation in local communities. At the same time, achievements in medicine produced methods for the amelioration and prevention of physiological problems. Responsive politicians and a favorable economy provided the impetus for legislation that established programs and provided services. In addition, successful challenges in courts of law contributed to expanded policies and programs on behalf of people with mental retardation. In particular, all children, including those who previously had been excluded from schools due to their disability, were granted the right to be educated at public expense. Early in the twenty-first century most children with mental retardation are educated in public schools with their peers, although many with severe disabilities are still consigned to segregated settings. Remaining issues for people with mental retardation include meaningful participation in all aspects of community living, social integration, equal opportunities in school and work, justice in the courts of law, and self-determination.

See also: Birth Defects; Education, Europe; Education, United States; Intelligence Testing; Special Education.


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