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Intellectual and developmental disability

Intellectual and developmental disability

August 11, 2022

The intellectual and developmental disability (DIyD) is the most frequent personal condition of disability in the population and among the students.

Intellectual disability concept

The expression "intellectual and developmental disability" was adopted in June 2006, after having been voted by the members of the American Association on Intellectual and Development Disabilities (AIDD). Previously it was called American Association on Mental Retardation (AAMR).

At least three names of this group have been known: "mental deficiency", "mental retardation" and "intellectual and developmental disability".

The AIDD has modified the denomination, the definition, the diagnosis and the classification as a consequence of the advances in the different disciplines involved in this topic: medicine, psychology and education.


A term that avoids stigmatization

The previous concept was changed by this new so that labels or social prejudices were minimized such as: visions focused on the deficit, on the slow and unbalanced mental functioning, etc.

The new name aims to take advantage of a new conception of development that is nourished by the contributions of sociocultural and ecological theories.

It allows a functional vision of development , which refers that a person can have different contexts and throughout the life cycle. In turn, it contributes the concept of disability that is nourished by the contributions of the International Classification of Functioning, Disability and of the WHO, and that recognizes the social origin of the difficulties experienced by the person who suffers DI and D.


On the other hand, he also understands intellectual disability as a developmental disorder which has much in common with other developmental problems that can affect children.

Objectives of this monograph

In this article We will try to provide a current vision of intellectual disability and development based on the paradigm of supports and in a conception of this disability as a function of the interaction between the independent functioning of the person and the contexts in which he lives, learns, works and enjoys; provide a general framework and some instruments for the evaluation of students with DIyD; and offer some answers to promote their development.

What do we mean by intellectual and developmental disability?

First of all, we are going to define the intellectual disability and the categories that constitute it.


What is intellectual disability?

exist four approximations in this field:

  • Social approximation : these people were historically defined as mentally retarded or deficient people because they were unable to adapt socially to their environment. The emphasis on the intellectual difficulties did not come until later and for a time what was most concerned was inappropriate social behavior.
  • Clinical approach : with the boom of the clinical model, the definition goal was changed. He went on to focus on the symptoms and clinical manifestations of the various syndromes. More attention was paid to the organic and pathological aspects of ID.
  • Intellectual approach : from the interest in intelligence as a construct and by intelligence tests, the approach to ID undergoes another change. It assumes an emphasis on the extent of the intelligence of these people expressed in terms of IQ. The most important consequence was the definition and classification of people with ID based on the scores obtained in the intelligence tests.
  • Intellectual and social approach Until 1959 the importance of these two components in the conception of ID was not recognized: the low intellectual functioning and the difficulties in adaptive behavior, which have remained to this day.

Theoretical and practical models on intellectual disability

Models with which people with intellectual disabilities have been conceptualized and who justified certain professional practices. They are distinguished three great models :

Beneficial-welfare model

From the late nineteenth century and during almost half of the twentieth century, people with disabilities were separated from society and entrusted to large charitable asylum institutions. The care they received was of assistance type and obeyed the charitable conception of public performance. They did not think it was something social or rehabilitative.

Rehabilitation-therapeutic model

It extends in Spain since the end of the IIGM, in the 70's. It supposes the adoption of the clinical model in the diagnosis and treatment of people with ID , and the predominance of specialization. The model coincides with the boom of the aforementioned clinical approach.The diagnosis of ID focuses on the individual's deficit and is classified into categories according to their IC. It is considered that the problem is within the subject and specialized institutions are created according to the nature of the problem to serve them.

Educational model

It started in our country in the 80s. It is characterized by the adoption of standardization principle in all stages of these people's lives. They begin to be considered with the same rights as their peers to education, health, work and a decent life. Education should be taught, if possible, in ordinary centers, the diagnosis should prioritize the capabilities of these people and focus on the supports they will need to respond to the demands of different life environments.

History about the definition of the concept

The AAIDD has changed the definition of DI up to 10 times. The last one was in 2002. It is a definition that goes beyond that of 1992 but maintains some of its key exceptions: the fact that mental retardation is not taken as an absolute trait of the person, but as the expression of the interaction between the person , with intellectual and adaptive limitations, and the environment; and the emphasis on supports.

In the definition of 1992 the categories disappear. They explicitly reject and affirm that people with mental retardation should not be classified on the basis of traditional categories, but that they should think about the supports they may need to increase their social participation.

Despite this, the 1992 definition meant a significant improvement for people with ID, but it was not exempt from criticism :

  • The imprecision for the purposes of diagnosis : it did not allow to establish clearly who was or not a person with mental retardation, who was eligible for certain services.
  • The lack of operational definitions for the investigation.
  • The fact that the evolutionary aspects are not sufficiently considered of these people.
  • The imprecision and the impossibility of measuring the intensity of support that these people require.

For this reason, the AAIDD proposes a new definition built from that of 1992. A system is created to diagnose, classify and plan supports for people with mental retardation.

The current definition

The new definition of mental retardation proposed by AAMR is as follows:

"Mental retardation is a disability that is characterized by significant limitations in both intellectual functioning and adaptive behavior expressed in conceptual, social and practical skills. This disability originates before the age of 18. "
  • "Mental retardation is a disability": a disability is the expression of limitations in the functioning of the individual within a social context that imply important disadvantages.
  • "... which is characterized by significant limitations in both intellectual functioning": intelligence is a general mental capacity that includes the fact of reasoning, planning, solving problems, abstract thinking, etc. The best way to represent them is by means of the IQ, which is two typical deviations below the average.
  • "... as in adaptive behavior expressed in conceptual, social and practical skills": adaptive behavior is the set of conceptual, social and practical skills that people learn to function in daily life. The limitations in this affect the typical execution of them, although they do not preclude a daily life.
  • "This capacity originates before 18 years": the 18 years correspond to the age in which in our society individuals assume adult roles.

With this definition it again affects the cognitive basis of the problem , but from a model that emphasizes the social and practical competence, which translates the recognition of the existence of different types of intelligence; a model that reflects the fact that the essence of mental retardation is close to the difficulties of coping with daily life, and the fact that limitations in social intelligence and practice explain many of the problems that people with ID have in community and at work.

It broadens the concept to other population groups, particularly the forgotten generation: expression that includes people with limit intelligence.

The aspects that change with this last definition are:

  • It includes a criterion of two standard deviations for the measurement of intelligence and adaptive behavior.
  • It includes a new dimension: participation, interaction and social role.
  • A new way to conceptualize and measure supports.
  • Develops and extends the three-step evaluation process.
  • A greater relationship between the 2002 system and other diagnostic and classification systems such as the DSM-IV, the ICD-10 and the ICF is favored.

As in the 1992, the definition incorporates the following five assumptions :

  1. Limitations on current functioning have to be considered within the context of typical community settings of their peers of my age and culture.
  2. An adequate assessment has to consider the cultural and linguistic diversity, and also the differences in communication, sensory, motor and behavioral factors.
  3. Within a single individual, limitations often coexist with strengths.
  4. An important objective when describing limitations is to develop a profile of the necessary supports.
  5. With appropriate personalized supports for a sustained period of time, the way of life of people with mental retardation will generally improve.

The Mental retardation it is understood in the framework of a multidimensional model that provides a way to describe the person through five dimensions that include all aspects of the individual and the world where he lives.

The model includes three key elements: person, the environment in which he lives, Y the props.

These elements are represented in the framework of the five dimensions that are projected in the daily functioning of the person through the supports. The supports have a mediating role in the lives of people with intellectual disabilitiesI.

It comes to a broader concept of ID than implies understanding that the explanation of the daily behavior of people is not exhausted from the effect of the five dimensions , but from the supports they can receive in their living environments.

Trends that have prevailed in the field of ID

  • An approach to ID from an ecological perspective that focuses on the interaction between the person and their environment.
  • Disability is characterized by limitations in functioning, rather than by a permanent feature of the person.
  • The multidimensionality of ID is recognized.
  • The need to link evaluation and intervention more firmly.
  • The recognition that an accurate diagnosis of ID often requires, along with the information available from the evaluation, a sound clinical judgment.

Characteristics and causes of intellectual disability and development

There are three important characteristics: limitations in intellectual functioning, limitations in adaptive behavior and need for support.

1. Limitations on intellectual functioning : intelligence refers to the student's ability to solve problems, pay attention to relevant information, abstract thinking, remember important information, generalize knowledge from one scenario to another, etc.

It is usually measured by means of standardized tests. A student has DI when his score falls two typical deviations below the mean.

The concrete difficulties that people with ID have

They usually present difficulties in these three areas :

to) Memory : people with ID usually show limitations in their memory, especially what is known as MCP, which has to do with their ability to remember information that must be stored for seconds or hours, as usually happens in class. It is more evident in the cognitive aspects than in the emotional ones. Strategies can be used to improve capacity.

b) Generalization : refers to the ability to transfer knowledge or behaviors learned in one situation to another. (from school to home, for example).

c) Motivation : the investigation reveals that the lack of motivation is associated to previous experiences of failure. The difficulties in successfully overcoming certain challenges of daily life at home and in the center makes them more vulnerable. If the sign of their experiences can be changed, motivation will also improve.

d) Limitations on adaptive behavior : people with ID usually have limitations in adaptive behavior. Adaptive behavior refers to the ability to respond to the changing demands of the environment; people learn to adjust / self-regulate behavior to different situations and contexts of life according to age, expectations, etc.

To identify a student's skills in this field, conceptual, social and practical skills are usually explored through scales constructed for this purpose. From the results can be designed educational activities that should be integrated into the curriculum.

Self-determination is the most central expression of the capacities inherent to adaptive behavior and that is of special relevance for people with ID. Its development is associated with a perception of higher or lower quality of life.

Causes of intellectual disability

Regarding the causes there are four categories:

  1. Biomedical : factors related to biological processes, such as genetic disorders or malnutrition.
  2. Social : factors related to the quality of social and family interaction, such as the stimulation or sensitivity of parents to the needs of their son or daughter.
  3. Behavioral : factors that refer to behavior that can potentially cause a disorder, such as accidents or the consumption of certain substances.
  4. Educational : factors that have to do with access to educational services that provide support to promote cognitive development and adaptive skills.

Keep in mind that these factors can be combined in different ways and proportions.

Intellectual disability and quality of life

One of the four characteristics of the emerging paradigm of disability is the well-being person who closely associates the concept of quality of life.

The recognition of the rights that people with ID have implicitly recognizes the right to a quality life.

Over time, the concept of quality of life has been applied to people with ID. This implies access to services, effectiveness and quality of these services that allow them to enjoy the same opportunities as others.

Access to a quality life entails recognizing the right to difference and the need for the services offered to be permeable to their particular conditions.

People with ID have certain characteristics that generate specific needs throughout their development, these needs draw the type of support they need to access services that make possible optimal living conditions.

Quality of life is defined as a concept that reflects the conditions of life desired by a person in relation to their life in the home and in the community; at work, and in relation to health and well-being.

Quality of life is a subjective phenomenon based on a person's perception of a set of aspects related to their life experience.

The concept of quality of life

According to Schalock and Verdugo, the concept of quality of life (CV) is being used in three different ways:

  • As a sensitizing concept that serves as a reference and guide from the perspective of the individual, indicating what is important to him.
  • As a unifying concept that provides a framework to conceptualize, measure and apply the CV construct.
  • As a social construct that becomes a predominant principle to promote the well-being of the person.

Promoting well-being in people with intellectual disabilities

In work to promote the well-being and quality of life of people with ID, the importance of eight central dimensions and certain indicators should be recognized:

  • Emotional well-being : happiness, self-concept, etc.
  • Relationships : intimacy, family, friendships, etc.
  • Material well-being : belongings, security, work, etc.
  • Personal development : education, skills, competences, etc.
  • physical well-being : health, nutrition, etc.
  • Self-determination : elections, personal control, etc.
  • Partner inclusion l : acceptance, participation in the community, etc.
  • Rights : privacy, freedoms, etc.

Services and resources for people with intellectual disabilities

The services and resources offered to people with ID throughout the life cycle must be aimed at satisfying their needs in order to be able to respond to the demands of the diverse contexts in which they develop and enable a life quality.

Characteristics that define a optimal environment :

  • Presence in the community : share ordinary places that define the life of the community.
  • Elections : the experience of autonomy, making decisions, self-regulation.
  • Competition : the opportunity to learn and perform functional and meaningful activities.
  • Respect : the reality of being valued in the community.
  • Participation in the community : the experience of being part of a growing network of family and friends.
About people with ID in the educational context: "Students with intellectual disabilities: evaluation, monitoring and inclusion"

Bibliographic references:

  • Gilman, C.J., Morreau, L.E. ALSC; Curriculum of adaptive skills. Personal life skills. Messenger editions.
  • Gilman, C.J., Morreau, L.E. ALSC; Curriculum of adaptive skills. Life skills in the home. Messenger editions.
  • Gilman, C.J., Morreau, L.E. ALSC; Curriculum of adaptive skills. Life skills in the community. Messenger editions.
  • Gilman, C.J., Morreau, L.E. ALSC; Curriculum of adaptive skills. Labor skills Messenger editions.
  • FEAPS. Positive behavioral support Some tools to deal with difficult behaviors.
  • FEAPS. Planning centered on the person. Experience of the San Francisco de Borja Foundation for people with intellectual disabilities.

Intellectual Disabilities (August 2022).


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