Intellectual Disabilities across the Lifespan
Chapter 1: Understanding Intellectual Disabilities
- In the history of treatment of persons with intellectual disabilities, advancements have
mostly been made by family members urging government and society.
- In tribes, people with intellectual disabilities were considered a burden, because of
consumption of food and water without contribution.
- Sterilization of persons with intellectual disabilities has been an issue for many years
and remains an issue in some countries.
- No single discipline has the breadth and depth of expertise and resources necessary to
fully support people who have intellectual disabilities
- Intellectual disabilities: encompasses a wide range of characteristics, it is both a label
of fact and a label of conjecture
- Fields in the involvement of intellectual disabilities:
o Biological and medical sciences, behavioural sciences (predominately psychology
but also anthropology and sociology), education, disciplinary collaboration
o Disciplinary collaboration: to better support individuals with intellectual
disabilities, professionals must coordinate efforts and involve the family.
Inclusion: implementing the principle of inclusion for all children with
disabilities involved placing a significant number of such children in
general education classrooms.
Serving children in an inclusive educational setting emphasized
the need for collaboration among professionals
- The concept of intellectual disabilities is made more complex because the varying
professions that deal with it hold widely divergent viewpoints.
- Definitions of intellectual disabilities have varied widely over the years between
- The AAMR (American Association on Mental Retardation) definition of mental
disabilities states that: Mental retardation is a disability characterized by significant
limitations both in intellectual functioning and in adaptive behaviour as expressed in
conceptual, social, and practical adaptive skills . The disability originates before age
o Assumption 1: limitations in present functioning must be considered within the
context of community environments typical of the individuals age group and
o Assumption 2: Valid assessment considers cultural and linguistic diversity as well
as differences in communication, sensory, motor, and behavioural factors
o Assumption 3: within an individual, limitations often coexist with strengths o Assumption 4: An important purpose of describing limitations is to develop a
profile of needed supports
o Assumption 5: When appropriate personalized supports over a sustained period
of the life functioning of the person with mental retardation generally will
- Measurement of adaptive behaviours: has always been a challenge, not achieving the
desired precision despite significant and continuing research efforts
- **See pg. 21; for AAMR Adaptive Behaviour Assumptions**
- Incidence and prevalence are often confused in the field of intellectual disabilities;
o Incidence: refers to the number of new cases identified during a given time
period (often 1 year)
o Prevalence: refers to all cases existing at a given time including both new cases
and old cases.
- The highest prevalence of intellectual disabilities in ages 6-19 across all levels of IQ
- Multiple classifications are used in the 2002 AAMR definition document to address
grouping individuals by service reimbursement or funding, research services,
communication about selected characteristics
- Cross-categorical definition and classification models have emerged because
conventional categories are not always effective and functional.
- Norm-referenced assessment: the measure of an individuals functioning in
comparison with some standard or group norm; testing, IQ, etc; valuable for grouping
- Criterion- referenced assessment: focuses on specific skills and looks at absolute level
of performance ; level of mastery an individual exhibits
- Multidisciplinary model: various professions approach a particular condition from
their own focus (e.g. psychological aspects of intellectual disabilities or medical
aspects of intellectual disabilities)
- Interdisciplinary model: attempts to develop knowledge bridges among professions
o From these efforts, sub disciplinary areas such as social psychology,
sociolinguistics, and neuropsychology have developed.
- Transdisciplinary model: developed as an effort to overcome the problems of the
other two models; emphasizes the role of a primary therapist, who acts as the contact
person for the service provisions, so the number of professionals with direct child
contact is minimal
Chapter 2: Diversity Issues - Cultural diversity involves critically important differences that require attention as one
examines intellectual disability both as a concept and in the context of individual
- Associated influences
o Poverty; exists at a rather high level among many culturally different groups and
creates a number of environmental disadvantages that may impair the childs
mental development (health care, nutrition, etc.)
o Cultural-social mores; social values that differ from culture to culture may result
in behaviour or performance deviation from the cultural majority, which some
might view as reflecting intellectual disability
o Language; language differences that create academic difficulties for some
culturally different children may place them in jeopardy of being considered as
having intellectual disability.
Minimizing assessment error and interpretation bias appears to be the
most satisfactory approach to provide the most effective instruction
possible for all children.
- Personnel and procedures involved in the assessment and intervention process may all
contribute to a biased overrepresentation of culturally different children as having
o Cultural bias in an experiment leads to inaccurate results
- A wide variety of factors as diverse as inherited genetic material and environmental
influences, such as nutrition, disease and toxic substances affect the course of human
- Professionals in the field of intellectual disability must change basic models of research
on intellectual disability so that the influences of cultural diversity on human
development can be more fully understood.
Chapter 3: Assessment Issues and Procedures
- Careful attention to the proper use of assessment instruments has a great impact on the
results of measurement
o Unfortunately, many instruments on the market do not give adequate attention
to sound measurement practices. The great demand from the field appears to
have resulted in inadequate instruments
- The purpose of any assessment greatly influences the procedures employed and the
way data are interpreted. Recognition of this has led to the articulation of such
important concepts as norm and criterion referencing and formative and summative
evaluation - Norm-referenced evaluation: early assessment developments focused on how an
individual performed, compared with others, particularly in the area of intelligence;
assessment in which the performance of an individual is compared with that of others.
- Criterion referenced evaluation: nearly synonymous with what norm-referenced
evaluation is not. It is not compared with a norm. It assesses specific skill areas,
individually, rather than generating a score based on a composite of several skills
o Best for direct linkage between assessment and classroom instruction
- Curriculum-based assessment: uses the sequential objective of the students
curriculum as the referent or criterion for evaluating progress.
o The specific application of referencing evaluation for a particular purpose
o The term objectives-referenced measurement is also sometimes used.
- Because each method for assessment serves different purposes, both norm-related and
criterion-related evaluation must be used.
- Formative evaluation: a framework in which assessment that focuses not on a desired
ultimate behaviour but rather on the next step in an instructional program.
- Summative evaluation: involves assessment of terminal behaviours and evaluates the
childs performance at the end of the given program
- Threats to assessment bias; discriminatory testing, cultural differences.
- EARLY LIFE
o Assessment procedures are quite different, depending on the age of the person
and the performance area being evaluated; identification of children who
already show learning disabilities and who have probability of developing
o Screening assessment is very important throughout the lifespan, but is especially
crucial in ear