Journal of Intellectual & Developmental Disability, December 2011; 36(4): 227–237

CONCEPTUAL PAPER

The evolving understanding of the construct of intellectual disability

ROBERT L. SCHALOCK

Hastings College, Nebraska, USA

J Intellect Dev Dis Downloaded from informahealthcare.com by Manukau Institute of Technology on 10/07/14

Abstract
This article addresses two major areas concerned with the evolving understanding of the construct of intellectual disabil-
ity. The first part of the article discusses current answers to five critical questions that have revolved around the general
question, “What is Intellectual Disability?” These five are what to call the phenomenon, how to explain the phenomenon,
how to define the phenomenon and determine who is a member of the class, how to classify persons so defined and iden-
tified, and how to establish public policy regarding such persons. The second part of the article discusses four critical
issues that will impact both our future understanding of the construct and the approach taken to persons with intellectual
disability. These four critical issues relate to the conceptualisation and measurement of intellectual functioning, the con-
stitutive definition of intellectual disability, the alignment of clinical functions related to diagnosis, classification, and
planning supports, and how the field resolves a number of emerging epistemological issues.
For personal use only.

Keywords: classifying, constitutive definition, defining, etiology, intellectual disability, intellectual functioning, naming,
operational definition

Introduction and overview

on the power of mental models that are defined as
Throughout history, there have been five critical deeply ingrained assumptions, generalisations, and
questions that have faced both persons with intel- images we have to understand the world (Senge,
lectual disability (ID) and the societies within which 2006). Throughout the history of ID a number of
they lived: (a) what to call the phenomenon, (b) how mental models have impacted the terminology used,
to explain the phenomenon, (c) how to define the the explanation and definition of the phenomenon,
phenomenon and determine who is a member of the classification system used, and the policies and
the class, (d) how to classify persons so defined and practices implemented. Historically, these models
identified, and (e) how to establish public policy that have focused on illness, personal defectology, and
aligns societal values with services and supports for categorisation. Mental models are beginning to
such persons. The purpose of the first section of this change as we understand better the construct of
article is to provide contemporary answers to each of ID and find answers to the five critical questions
these five critical questions. The second section of addressed in the article’s first section. These more
the article discusses four critical issues that provide current mental models are those that focus on (a)
the framework for future discussions and dialogue. human potential and the ameliorating effects of envi-
These four relate to the conceptualisation and mea- ronmental factors; (b) an emphasis on social inclu-
surement of intellectual functioning, the constitutive sion, self-determination, personal development, and
definition of intellectual disability, the alignment of community inclusion; and (c) the provision of indi-
clinical functions related to diagnosis, classification, vidualised supports (Schalock & Verdugo, in press;
and supports planning, and how the field resolves a Schalock, Verdugo, Bonham, Fantova, & van Loon,
number of emerging epistemological issues. 2008).
How one answers these critical questions and It is important to make explicit from the begin-
addresses these critical issues is based in large part ning the author’s “mental model.” First, I was a

Correspondence: Robert L. Schalock, PhD, PO Box 285, Chewelah, Washington 99109, USA. E-mail: rschalock@ultraplix.com

ISSN 1366-8250 print/ISSN 1469-9532 online © 2011 Australasian Society for Intellectual Disability, Inc.
DOI: 10.3109/13668250.2011.624087
 228 R. L. Schalock

member of the American Association on Intellectual terms that have been used historically such as men-
and Developmental Disability (AAIDD; formerly tal retardation or mental deficiency (Schroeder,
AAMR) committee that developed and published Gerry, Gertz, & Velazquez, 2002), and is more con-
the 1992, 2002, and 2010 definition, classification, sistent with international terminology, including
and systems of supports manuals. Second, I have journal titles, published research, and organisation
been involved in cross-cultural research on ID-re- names (Parmenter 2004; Schalock, Luckasson, &
lated definitional and application issues (Schalock, Shogren, 2007; Schroeder et al., 2002; Wehmeyer
2010; Schalock & Luckasson, 2004) and the inter- et al., 2008).
national implications of the emerging disability par-
adigm on policies and practices (Schalock, 2004).
Explaining the phenomenon
Third, I have discussed the relationships among the
articles of the 2006 United Nations’ Convention on Explanations of the phenomenon (i.e., intellectual
the Rights of Persons with Disabilities, the concept disability) have varied historically from those rooted
J Intellect Dev Dis Downloaded from informahealthcare.com by Manukau Institute of Technology on 10/07/14

of quality of life, and the measurement and use of in deification to those rooted in defectology. Cur-
personal outcomes to enhance public policy and ser- rently, ID is viewed as a disability characterised by
vice delivery system practices (Schalock, Bonham, significant limitations in intellectual functioning and
& Verdugo, 2008). Finally, I have suggested ways to adaptive behaviour and manifest during the develop-
integrate the World Health Organization’s Interna- mental period. ID is also a multidimensional state
tional Classification of Functioning, Disability and of human functioning. Understanding these two key
Health (WHO-ICF) and AAIDD models of dis- concepts—the construct of disability and the mul-
ability, quality of life, and the supports paradigm in tidimensionality of human functioning—is essential
order to enhance professional practices in the field of to not only explaining the phenomenon, but also in
ID (Buntinx & Schalock, 2010). These experiences providing a framework to understand and explain
are reflected throughout the article, which attempts its etiology.
to address both US and international perspectives
For personal use only.

on the issue. The construct of disability. The construct of intellectual

disability belongs within the general construct of dis-
ability, which focuses on the expression of limitations
Answering the five critical questions in individual functioning within a social context and
represents a substantial disadvantage to the individual.
Naming the phenomenon
The current social-ecological conception of disability
Naming involves attaching a specific term to some- has emerged over the last two decades due primarily
thing or someone. Naming is a powerful process that to an increased understanding of the process of dis-
carries many messages about perceived value and ablement and its amelioration. Major factors in this
human relationships (Luckasson & Reeve, 2001), include (a) the research on the social construction of
and is the prerequisite for defining and ultimately illness and the extensive evolution impact that societal
classifying persons who are members of the class attitudes, roles, and policies have on the ways that indi-
(Simeonsson, Granlund, & Bjorck-Akersson, 2006). viduals experience health disorders (Aronowitz, 1998);
The name (or term) used to refer to persons with ID (b) the blurring of the historical distinction between
has historically varied significantly. Even now, one biological and social causes of disability (Institute of
finds considerable variation in terminology interna- Medicine, 1991); and (c) the recognition of the multi-
tionally. As discussed in more detail in Brown (2007), dimensionality of human functioning (Buntinx, 2006;
Brown and Radford (2007), and Schalock (2010), Luckasson et al., 2002; Wehmeyer et al., 2008; World
these terms include “mental deficiency,” “mental Health Organization, 2001). Because of these factors
handicap,” “mental subnormality,” “developmental the concept of disability has evolved from a person-
disability” (especially in Canada), and “learning dis- centred trait or characteristic (often referred to as a
abilities” (especially in the United Kingdom). “deficit”) to a focus on functional limitations that
The term intellectual disability is increasingly being reflect an inability or constraint in both personal func-
used internationally. This increased usage reflects the tioning and performing roles and tasks expected of an
changed construct of disability, aligns better with individual within a social environment (Bach, 2007;
current professional practices that focus on func- DePoy & Gilson, 2004; Hahn & Hegamin, 2001;
tional behaviours and contextual factors, provides Nagi, 1991). This emerging focus is consistent with
a logical basis for individualised supports provision the personal empowerment and self-determination
due to its basis in a social-ecological framework, movement, a stronger emphasis on personal rights
is less offensive to persons with the disability than and desired personal outcomes, and an awareness of
 What is intellectual disability? 229

the effects of discrimination and marginalisation on Defining the class

persons with disability (Oliver, 1996; Rioux, 1997;
The third critical question relates to how to define
Schalock, 2004).
the phenomenon and determine who is a member of
The importance of this evolutionary change in the
the class. In defining the class, the name or term is
construct of disability is that ID is no longer consid-
explained as precisely as possible. As stated by Felce
ered entirely an absolute, invariant trait of the person
(2006, p. xiii), “the clarity of definition is clearly
(DeKraai, 2002; Devlieger, Rusch, & Pfeiffer, 2003;
necessary to science.” The definition should estab-
Switzky & Greenspan, 2006). Rather, this social-eco-
lish the boundaries of the term and separate who or
logical conception of ID exemplifies the interaction
what is included within the term from whom or what
between the person and their environment, focuses
is outside the term. The importance of a clear opera-
on the role that individualised supports can play in
tional definition is that it establishes meaning, helps
enhancing individual functioning, and allows for the
meet the basic human drive for understanding, and
pursuit and understanding of “disability identity”
J Intellect Dev Dis Downloaded from informahealthcare.com by Manukau Institute of Technology on 10/07/14

affects a person’s social and legal status (Greenspan

whose principles include self-worth, subjective well-
& Switzky, 2006; Schalock et al., 2007).
being, pride, common cause, policy alternatives, and
An important distinction can be made between
engagement in political action (Powers, Dinerstein,
an operational and constitutive definition of ID. An
& Holmes, 2005; Putnam, 2005; Schalock, 2004;
operational definition focuses on the operations with
Vehmas, 2004).
which a construct such as ID can be observed and
measured. In distinction, a constitutive definition
Multidimensionality of human functioning. As pro- defines the construct of ID in relation to other con-
posed by the World Health Organization (2001) structs and thus helps to understand the theoretical
and AAIDD (Schalock et al., 2010) human func- underpinnings of the construct. Before discussing
tioning is an umbrella term for all life activities. this distinction in greater detail, a little history is
The ICF model of human functioning involves required for context and to appreciate our evolv-
For personal use only.

six components: health condition (disability and ing understanding of the construct of ID. Histori-
disease), body functions and structures (impair- cally, four approaches have been used to identify the
ments), activities, participation, environmental class of persons with ID: social, clinical, intellectual,
factors, and personal factors. The AAIDD model and dual-criterion. Initially, persons (with ID) were
includes five components of human functioning defined or identified because they failed to adapt
(intellectual abilities, adaptive behaviour, health, socially to their environment. Since an emphasis
participation, and context) and focuses on the key on intelligence and the role of “intelligent people”
role played by individualised supports in enhanc- in society was to come later, the oldest historical
ing the level of human functioning (Buntinx & approach was to focus on social behaviour and the
Schalock, 2010). “natural behavioral prototype” (Greenspan, 2003).
With the rise of the medical model, the focus for
The etiology of intellectual disability. Increasingly, the defining the class shifted to one’s symptom com-
etiology of ID is conceptualised as a multifactorial plex and clinical syndrome. This approach did not
construct composed of four categories of risk fac- negate the social criterion, but gradually there
tors that interact across time, including across the was a shift toward the role of organicity, heredity,
life of the individual and across generations from pathology, and the need for segregation (Devlieger
parent to child. This multifactorial understanding et al., 2003). With the emergence of intelligence as
of etiology is replacing the historical approach that a viable construct to explain the class and the rise
divided etiology of ID (referred to then as “mental of the mental testing movement, the criterion for
retardation”) into two broad types: those due to defining the class shifted to intellectual functioning as
biological origin and those due to psychosocial dis- measured by an IQ test. This emphasis led to the
advantage. The multifactorial approach to etiology emergence of IQ-based statistical norms as a way to
expands the list of causal factors in two directions: both define the class and classify individuals within it
types of factors (biomedical, social, behavioural, (Devlieger, 2003). In reference to the dual criterion
educational) and timing of factors (prenatal, peri- approach, the first attempt to use both intellectual
natal, and postnatal). Table 1, which is based on and social criteria to define the class was found in the
the work of Emerson, Fujiura, and Hatton (2007), 1959 American Association on Mental Deficiency’s
Schalock et al. (2010), and Walker et al. (2007), (AAMD) manual (Heber, 1959), which defined ID
summarises key risk factors from each of these (then referred to as “mental deficiency”) as referring
perspectives. to sub-average general intellectual functioning which
 230 R. L. Schalock

Table 1. Examples of prenatal, perinatal, and postnatal risk factors in intellectual disability

Prenatal
• Biomedical: chromosomal disorders, metabolic disorders, transplacental infections (e.g., rubella, herpes, HIV), exposure to toxins
or teratogens (e.g., alcohol, lead, mercury), undernutrition (e.g., maternal iodine deficiency)
• Social: poverty, maternal malnutrition, domestic violence, lack of prenatal care
• Behavioural: parental drug use, parental immaturity
• Educational: parental disability without supports, lack of educational opportunities
Perinatal
• Biomedical: prematurity, birth injury, hypoxia, neonatal disorders, rhesus incompatibility
• Social: lack of access to birth care
• Behavioural: parental rejection of caretaking, parental abandonment of child
• Educational: lack of medical referral for intervention services at discharge
Postnatal
• Biomedical: traumatic brain injury, malnutrition, degenerative/seizure disorders, toxins
• Social: lack of adequate stimulation, family poverty, chronic illness, institutionalisation
J Intellect Dev Dis Downloaded from informahealthcare.com by Manukau Institute of Technology on 10/07/14

• Behavioural: child abuse/neglect, domestic violence, difficult child behaviours

• Educational: delayed diagnosis, inadequate early intervention, inadequate special education services, inadequate family support

originates during the developmental period and is to age 18. Each of the first two criteria (significant
associated with impairments in maturation, learn- limitations in intellectual functioning and adaptive
ing, and social adjustments. In the 1961 AAMD behaviour) is defined in terms of cut-off scores and
manual (Heber, 1961), maturation, learning and interpreted in reference to a statistical confidence
social adjustments were folded into a single, largely interval (Schalock et al., 2010). More specifically,
undefined new term, “adaptive behavior.” The dual- the “significant limitations in intellectual function-
criterion approach has also included age of onset as ing” criterion for a diagnosis of ID is an IQ score
an accompanying element. that is approximately two standard deviations below
For personal use only.

the mean, considering the standard error of mea-

Operational definition of intellectual disability. An surement for the specific instruments used and the
operational definition of ID includes three key instruments’ strengths and limitations. Although
components: (a) the actual definition, (b) the the two standard deviations below the mean crite-
construct’s boundaries, and (c) the use of the rion might be considered arbitrary, it has been used
statistical concept of standard error of measure- widely since 1973 (Schalock et al., 2007, 2010).
ment to establish a statistical confidence inter- Analogously, the “significant limitations in adaptive
val within which the person’s true score falls. behavior” criterion for a diagnosis of ID is perfor-
Based on a review of the international literature mance that is approximately two standard deviations
(Schalock, 2010), the most commonly used opera- below the mean of either (a) one of the following
tional definition of ID is that promulgated by the three types of adaptive behaviour: conceptual, social,
American Association of Intellectual and Devel- or practical; or (b) an overall score on a standardised
opmental Disabilities (AAIDD). According to this measure of conceptual, social, and practical skills. As
operational definition: with the intellectual functioning criterion, the assess-
ment instrument’s standard error of measurement
Intellectual disability is characterized by signi-
must be considered when interpreting the individu-
ficant limitations both in intellectual func-
tioning and in adaptive behavior as expressed al’s obtained score.
in conceptual, social, and practical adaptive skills. The results of any psychometric assessment
This disability originates before age 18. (Schalock need to be evaluated in terms of the accuracy of
et al., 2010, p. 1) the instrument used. Obtained scores are subject
to variability as a function of a number of potential
Other ID-related definitions can be found in sources of error including variations in test perfor-
Brown (2007) and Brown and Radford (2007). mance, examiner’s behaviour, cooperation of the
In reference to the construct’s boundaries, cut-off test taker, and other personal and environmental
scores are used to identify (i.e., diagnose) a person factors. The term standard error of measurement
who falls within the class. Based on the operational (SEM), which varies by test, subgroup, and age
definition of ID just presented, the identification of group, is used to quantify this variability and pro-
ID is based on three criteria: significant limitations vide the basis for establishing a statistical confidence
in intellectual functioning, significant limitations in interval around the obtained score within which the
adaptive behaviour as expressed in cognitive, social, person’s true score falls. From the properties of the
and practical adaptive skills, and age of onset prior normal curve, a range of statistical confidence can
 What is intellectual disability? 231

be established with parameters of at least one SEM categorisation of various kinds of observations. Clas-
(66% probability) or parameters of two SEM (95% sification systems are used typically for four purposes:
probability). funding, research, services/supports, and communi-
cation about selected characteristics of persons and
Constitutive definition of intellectual disability. Although their environments. Three classification systems are
the operational criteria (based on the operational currently used most frequently internationally in the
definition of ID) for diagnosis have been generally field of ID: the International Classification of Diseases,
consistent for the last 50 ⫹ years (Schalock et al., Ninth Revision, Clinical Modification (ICD-9-CM;
2007), the construct underlying the term ID (and Medicode, 1998), the International Classification of
thus, the constitutive definition of ID) has changed Diseases, Tenth Revision (ICD-10; WHO, 1993),
significantly due to the impact of the social-ecological and the Diagnostic and Statistical Manual of Mental
model of disability. In this model, ID is understood Disorders, Fourth Edition (DSM-IV; American Psy-
as a multidimensional state of human functioning in chiatric Association, 2000). In each system, mental
J Intellect Dev Dis Downloaded from informahealthcare.com by Manukau Institute of Technology on 10/07/14

relation to environmental demands. retardation (the term ID is not used) is coded pri-
A constitutive definition of ID is used to define marily on the basis of full scale IQ scores.
the construct in relation to other constructs and thus As the field of ID moves increasingly to an eco-
helps to understand better the theoretical underpin- logical focus and a supports paradigm, a number
nings of the construct. For example, Wehmeyer et al. of current policies and practices have emerged that
(2008) discuss the significant differences between the require a broader, multidimensional approach to
construct that underlies the term intellectual disability classification. These changes relate to: (a) group-
and the construct underlying the term mental retarda- ing for reimbursement/funding on the basis of some
tion. The major difference is in regard to where the combination and weighting of levels of assessed
disability resides: the former construct (mental retarda- support need, level of adaptive behaviour, health
tion) viewed the disability as a defect within the per- status, and/or contextual factors such as residential
son, while the current construct (intellectual disabil- platform and geographical location; (b) research
For personal use only.

ity) views the disability as the fit between the person’s methods that focus on multidimensional predictors
capacities and the context within which the person is of human functioning and/or desired personal out-
to function. The term mental retardation referred to a comes; and (c) individualised services and supports
condition internal to the person (e.g., slowness of mind); based on the pattern and intensity of assessed sup-
intellectual disability refers to a state of functioning, not port needs across dimensions of human functioning
a condition. Both constructions see the condition (as and life activity areas. As a result of these changes in
in mental retardation) or the state of functioning (as policies and practices, multidimensional classifica-
in intellectual disability) as best defined in terms of tion frameworks are emerging that reflect the multi-
limitations in typical human functioning. dimensionality of human functioning discussed ear-
Thus, a constitutive definition of ID defines the phe- lier. One such framework, which is consistent with
nomenon in terms of limitations in human functioning, both the AAIDD system (Schalock et el., 2010) and
emphasises an understanding of disability consistent the ICF model (WHO, 2001), is shown in Table 2.
with an ecological and multidimensional perspective, Although “exemplary measures” are referenced in
and recognises the significant role that individualised the table, it is beyond the scope of this article to list
supports play in improving human functioning. The specific assessment instruments or scales. Further-
advantages to a constitutive definition of ID are that more, considerable work is yet to be done in this
it recognises the vast biological and social complexi- area—work that is currently being engaged in by one
ties associated with ID (Baumeister, 2006; Switzky or more ICD-11 and AAIDD work groups.
& Greenspan, 2006), captures the essential charac-
teristics of a person with this disability (Simeonsson
Establishing public policy
et al., 2006), establishes an ecological framework for
supports provision (Thompson et al., 2009), and pro- The final critical question relates to establishing pub-
vides a solid conceptual basis to differentiate among lic policy that aligns societal values with services and
persons with other cognitive and developmental supports for persons with ID. Currently, international
disabilities (Thompson & Wehmeyer, 2008). disability policy regarding persons with ID is pre-
mised on a number of core concepts and principles
that are: (a) person-referenced, such as inclusion,
Classifying members of the class
empowerment, individualised and relevant supports,
All classification systems have as their fundamental productivity and contribution, and family integrity
purpose the provision of an organised scheme for the and unity; and (b) service-delivery referenced, such
 232 R. L. Schalock

Table 2. Exemplary components of a multidimensional classification system

Dimension Exemplary measures Classification scheme

Intellectual abilities Individually administered IQ tests IQ ranges or levels

Adaptive behaviour Adaptive behaviour scales Adaptive behaviour levels
Health Health and wellness inventories Health status
Mental health measures Mental health status
Etiologic assessment Risk factors
Etiology groupings
Participation Community integration scales Degree of community integration
Community involvement scales Degree of community involvement
Measures of social relationships Level of social interactions
Measures of home life Level of in-home activities
Context Environmental assessments (physical, social, attitudinal) Environmental status
Personal assessments (motivation, coping styles, Personal status
J Intellect Dev Dis Downloaded from informahealthcare.com by Manukau Institute of Technology on 10/07/14

learning styles, lifestyles)

Supports Support need scales Level of needed support
Functional behaviour assessment Pattern of needed supports

as antidiscrimination, coordination and collabora- vary from highly segregated classrooms, to resource
tion, and accountability (Brown & Percy, 2007; rooms, to schools providing full inclusion for stu-
Montreal Declaration, 2004; Salamanca Statement, dents with ID; (b) residential options that vary from
1994; Shogren, Bradley, Gomez, Yeager, & Schalock, large, congregate living facilities and nursing homes,
2009). These concepts and principles have resulted to group homes, to supported community living pri-
in significant changes in service delivery policies and vate residences (It should be noted, however, that
practices, and a significant effort to conceptualise across the globe, only a small proportion of persons
and measure important life domains. In reference with ID live in residential settings; most reside with
For personal use only.

to the former, we have seen internationally poli- their family [Emerson et al., 2007].); (c) occupa-
cies and practices enacted that provide education, tional opportunities that vary from day activity cen-
community living and employment opportunities, ters, to sheltered workshops, to general work skills
technological supports and assistive technology, and vocational preparation, to integrated employ-
person-centred planning, and a framework to assess ment; and (d) support services that include special-
person- and family-referenced valued outcomes. In ised health and behaviour supports, leisure activities,
reference to the latter, the concepts and principles transportation, assistive technology, rights and advo-
mentioned above have been operationalised in the cacy support, and/or nutritional assistance.
following eight universally recognised life domains The concept of supports is being applied to per-
(United Nations, 2006): rights (access and privacy); sons with ID in different ways. For some, the sup-
participation; autonomy, independence, and choice; ports orientation has brought together the related
physical well-being; material well-being (work and practices of person-centred planning, personal
employment); inclusion, accessibility, and participa- growth and development opportunities, community
tion; emotional well-being (freedom from exploita- inclusion, self-determination, empowerment, the
tion, violence, and abuse); and personal development application of positive psychology, and the applica-
(education and rehabilitation). Although there is con- tion of a “systems of supports” that includes policies
siderable variability across countries, the net effect of and practices, incentives, cognitive supports (i.e.,
these concepts, principles, and related changes has assistive technology), prosthetics, skills and knowl-
been the development of an array of services and edge, environmental accommodation, and profes-
supports for persons with ID and an increasing focus sional services (Shogren, Wehmeyer, Buchanan, &
on measuring public policy outcomes. Lopez, 2006; Thompson et al., 2009). For others, we
Array of services and supports. As discussed more have seen the integration of a quality of life frame-
fully by Emerson et al. (2007) and Mercier, Sax- work into the individualised planning process so as
ena, Lecomte, Cumbrera, and Harnois (2008), to align supports provision within the quality of life
persons with disabilities, including those with ID, framework, and thus focus on the role that individu-
are provided in many countries with an array of alised supports play in the enhancement of quality
educational, residential, occupational, and support of life-related personal outcomes (van Loon, 2008).
services. Although the availability and composi- And for others, supports are provided through
tion vary across countries, the general parameters a community-based rehabilitation model, which con-
of this array are (a) educational opportunities that sists of small programs implemented through the
 What is intellectual disability? 233

combined efforts of those with disability, their and supports planning, and how the field resolves a
families, and the community using indigenous sup- number of emerging epistemological issues.
ports (McConkey & O’Toole, 1995). According to
Emerson et al. (2007), this model remains the cen-
terpiece of international development strategies. Conceptualisation and measurement of intellectual
functioning
Measuring public policy outcomes. Public policy out-
Historically, there have been three broad conceptual
comes can be used for multiple purposes including
frameworks used to describe and measure intel-
analysing the impact of specific public policies, mon-
lectual functioning: intelligence as a general factor
itoring the effectiveness and efficiency of services
(e.g., Gottfredson, 1997), intelligence as a multi-
and supports, providing a basis for continuous qual-
trait, hierarchical phenomenon (e.g., Carroll, 1993),
ity improvement and performance enhancement,
or intelligence as a multidimensional construct
meeting the increasing need for accountability, and
(Gardner, 1998; Horn & Cattell, 1966; Naglieri &
J Intellect Dev Dis Downloaded from informahealthcare.com by Manukau Institute of Technology on 10/07/14

helping establish the parameters of best practices

Das, 1997). Although the pendulum swings back and
(Shogren & Turnbull, 2010). Although just appear-
forth, recent years have brought an increased empha-
ing in the field of ID, public/social policy outcomes
sis on a multidimensional conceptual approach, even
are being assessed in three broad areas: personal,
though currently the most valid assessment of intel-
family, and societal. The framework used to mea-
lectual functioning employs individually adminis-
sure these outcomes is based on the delineation
tered, standardised assessment instruments that are
of valued life domains and the assessment of core
based on the general factor conceptual framework
indicators associated with each life domain. Table 3
(Schalock et al., 2010).
summarises exemplary outcome domains, including
Although our current definition and diagnostic-
relevant published literature. The outcome domains
classification processes are still based largely on con-
listed in Table 3 are consistent with the specific
ceptualising and measuring intelligence as a general
articles found in the 2006 UN Convention on the
For personal use only.

factor, the increased emphasis on the multidimen-

Rights of Persons with Disabilities.
sionality of intelligence will have significant implica-
tions in the future as to how we operationally define
ID. For example, the movement towards conceptu-
Addressing four critical issues
alising intellectual functioning as a multidimensional
Addressing the five critical questions just discussed construct could be the basis for an operational defi-
has resulted in an increasing understanding of the nition of ID. This is reflected in Sternberg’s (1988)
construct of ID. However, in the author’s opinion, triarchic model of intelligence as being composed of
there are four critical issues that need to be addressed analytical, creative, and practical components, and/
in the future as we continue to understand better the or Greenspan’s (2006) tripartite model of adap-
nature of the ID construct and the approach taken to tive intelligence as being composed of conceptual,
persons with intellectual and closely related develop- practical, and social components. This changed
mental disability. These four relate to the conceptual- operational definition of ID would also be consistent
isation and measurement of intellectual functioning, with the potential merging of the concepts of intel-
the constitutive definition of ID, the alignment of ligence and adaptive behaviour into a model of per-
clinical functions related to diagnosis, classification, sonal competence based on conceptual, social, and

Table 3. Public policy outcome measures: Domains and referent group

Person-Referenced Outcome Domainsa

Rights Personal Development Self-Determination Physical Well-Being
Inclusion Emotional Well-Being Material Well-Being Participation
Family-Referenced Outcome Domainsb
Family Interaction Emotional Well-Being Personal Development
Parenting Physical Well-Being Financial Well-Being
Community/Civic Involvement Disability-Related Supports
Societal-Referenced Outcomesc
Socioeconomic Position Health Subjective Well-Being
aBased on the work of Alverson, Bayliss, Naranjo, Yamamoto, and Unruh (2006), Gardner and Carran (2005), Bradley and Moseley

(2007), Schalock and Verdugo (2002). bBased on the work of Aznar and Castañón (2005), Isaacs et al. (2007), Summers et al. (2005).
cBased on the work of Arthaud-Day, Rode, Mooney, and Near (2005), Emerson, Graham, and Hatton (2006), Emerson and Hatton

(2008).
 234 R. L. Schalock

practical skills (Schalock, 1999, 2006; Thompson & program standards (Walter, Helgenberger, Wiek, &
Wehmeyer, 2008). Scholz, 2007). This research approach also incorpo-
A number of potential benefits would accrue with rates a more functional perspective of ID based on
such a change in the conceptualisation and mea- a multidimensional model of etiology and the prin-
surement of intellectual functioning. Chief among ciples of human potential, positive psychology, and
these would be (a) a subtle, but important, shift in self-determination (Emerson et al., 2007; Schalock,
terminology from “intelligence” (a unitary concept) Bonham, & Verdugo, 2008; Shogren et al., 2006;
to “intellectual functioning” (a multidimensional Wehmeyer et al., 2008).
concept); (b) a closer alignment between the term
intellectual disability and the diagnostic criteria Alignment of clinical functions
(e.g., significant limitations in conceptual, social,
The third critical issue involves a better understand-
and practical intelligence/intellectual skills); (c) a
ing of the role of assessment in ID and the alignment
singular operational definition of ID that focuses on
J Intellect Dev Dis Downloaded from informahealthcare.com by Manukau Institute of Technology on 10/07/14

of three clinical functions: diagnosis, classification,

the multidimensionality of intelligence, rather than
and planning supports. As discussed more fully in
including both intelligence and adaptive behaviour
Schalock et al. (2010) and Schalock and Luckasson
in the operational definition; (d) a shift towards an
(2004), an assessment framework needs to meet three
emphasis on specific skills associated with each type
criteria: the assessment tools and processes should
of “intelligence” that are amenable to individualised
match the purpose for the assessment, the assess-
supports rather than focusing—as many do—on the
ment findings should be as valid as possible, and
perceived invariant nature of one’s “IQ”; and (e) a
the results should be both useful and purposefully
clear and needed research focus on the development
applied. Furthermore, such an assessment frame-
of valid measurement instruments that assess con-
work needs to align data from assessment instru-
ceptual, social, and practical intelligence (or intel-
ments and strategies to the three clinical functions
lectual skills).
of diagnosis, classification, and planning supports.
At least three things are required for such a change
For personal use only.

According to such a framework:

to occur and be accepted by the scientific commu-
nity. First, the operational definition of intelligence (a) ID is diagnosed using assessment information
would need to be changed to reflect the multidi- obtained from standardised and individually
mensionality of intellectual functioning. Second, administered instruments. If the criteria for a
valid measures of social and practical intelligence diagnosis of ID are met, the diagnosis may be
(or conceptual, social, and practical intellectual applied to achieve several focused purposes
skills) would need to be developed. Third, we would including, but not limited to, establishing the
need to discard the (somewhat arbitrary) distinction presence of the disability in an individual
between “intelligence” as reflective of maximum per- and confirming an individual’s eligibility for
formance and “adaptive behaviour” as reflective of services, benefits, and legal protections.
typical performance. (b) Multiple classification systems are used to
group or classify individuals with ID (or
the individuals themselves) for several pur-
Constitutive definition of intellectual disability
poses such as conducting research, providing
As discussed previously, a constitutive definition of service reimbursement/funding, developing
ID includes an ecological construct of disability, services and supports, and communicating
an emphasis on the multidimensionality of human about selected characteristics. As shown in
functioning, and a supports paradigm that focuses Table 2, a multidimensional classification
on the provision of a person-centred system of system is based on the assessment of intellec-
supports that enhances human functioning. How tual functioning, adaptive behaviour, health,
this critical issue “plays out” in the future impacts participation, context, and/or the pattern or
potentially how we define ID and how the param- intensity of needed supports. The particular
eters of best practices are established. A transdis- classification system selected should be con-
ciplinary approach to research that jointly involves sistent with a specific purpose and used to
researchers and practitioners is essential in further- benefit members of the group.
ing our understanding of a constitutive definition (c) Planning supports should integrate assessment
of ID. Such an approach results in both scientific information obtained from standardised and
(understanding) and social (application) effects, and informal measures of individual support needs,
allows the field to better integrate principles and person-centred planning information, and
methods into public policy, program practices, and other input from knowledgeable informants.
 What is intellectual disability? 235

Epistemological issues Aronowitz, R. A. (1998). Making sense of illness: Science, society, and
disease. Cambridge, UK: Cambridge University Press.
In the future, we also need to address at least five Arthaud-Day, M. L., Rode, J. C., Mooney, C. H., & Near, J. P.
epistemological issues. Chief among these are those (2005). The subjective well-being construct: A test of its con-
related to (a) the construct of disability, how intel- vergent, discriminate, and factorial validity. Social Indicators
Research, 74, 445–476. doi:10.1007/s11205-004-8209-6
lectual disability fits within the general construct of Aznar, A. S., & Castañón, D. G. (2005). Quality of life from the
disability, and the relation of ID to other develop- point of view of Latin American families: A participative
mental disabilities (Brown & Percy, 2007; Finlay & research study. Journal of Intellectual Disability Research, 49,
Lyons, 2005; Schalock & Luckasson, 2004; Switzky 784–788. doi:10.1111/j.1365-2788.2005.00752.x
& Greenspan, 2006); (b) the social construction of Bach, M. (2007). Changing perspectives on developmental dis-
abilities. In I. Brown & M. Percy (Eds.), A comprehensive guide
ID (Rapley, 2004); (c) the ethical analysis of the to intellectual and developmental disabilities (pp. 35–57). Balti-
concept of disability (Vehmas, 2004); (d) whether more, MD: Brookes.
the elements of the ID construct and the construct Baumeister, A. A. (2006). Mental retardation: Confusing senti-
J Intellect Dev Dis Downloaded from informahealthcare.com by Manukau Institute of Technology on 10/07/14

itself are relevant internationally due to the cul- ment with science. In H. N. Switzky & S. Greenspan (Eds.),
tural relativity of the constructs of intellectual func- What is mental retardation? Ideas for an evolving disability in the
21st century (Rev. and updated ed., pp. 95–126). Washington,
tioning and adaptive behaviour (Emerson et al., DC: American Association on Mental Retardation.
2007); and (e) whether the “functionalist-objectivist Bradley, V. J., & Moseley, C. (2007). National core indicators:
paradigm” of ID can be reconciled with the “inter- Ten years of collaborative performance measurement. Intel-
pretative-subjective paradigm” of ID (Switzky & lectual and Developmental Disabilities, 45, 354–358.
Greenspan, 2006). doi:10.1352/0047-6765(2007)45[354:NCITYO]2.0.CO;2
Brown, I. (2007). What is meant by intellectual and developmen-
In conclusion, the resolution of these epistemolog- tal disabilities? In I. Brown & M. Percy (Eds.), A comprehensive
ical issues—and indeed how we answer the question, guide to intellectual and developmental disabilities (pp. 3–15).
“What is ID?”—will be facilitated by a better under- Baltimore, MD: Brookes.
standing of the multidimensionality of intelligence, Brown, I., & Percy, M. (2007). A comprehensive guide to intellectual
clearly articulated operational and constitutive defi- and developmental disabilities. Baltimore, MD: Brookes.
For personal use only.

Brown, I., & Radford, J. P. (2007). Historical overview of intel-

nitions of ID, the employment of a transdisciplinary lectual and developmental disabilities. In I. Brown & M. Percy
approach to research, and a clear understanding of (Eds.), A comprehensive guide to intellectual and developmental
the role of assessment in the three clinical functions disabilities (pp. 17–33). Baltimore, MD: Brookes.
of diagnosis, classification, and planning supports. Buntinx, W. H. E. (2006). The relationship between WHO-ICF
Additionally, their resolution as part of the evolv- (International Classification of Functioning, Disability, and
Health) and the AAMR 2002 system. In H. N. Switzky & S.
ing understanding of the construct of ID will be Greenspan (Eds.), What is mental retardation? Ideas for an
facilitated by a better understanding of the multidi- evolving disability in the 21st century (Rev. and updated ed., pp.
mensionality of human functioning, an expanding 303–323). Washington, DC: American Association on Mental
understanding of the etiology of ID and the risk Retardation.
factors involved in its manifestation, and a general Buntinx, W. H. E., & Schalock, R. L. (2010). Models of disability,
quality of life, and individualized supports: Implications for
movement internationally towards the recognition of professional practice in intellectual disability. Journal of Policy
the legal and human rights of persons with ID and and Practice in Intellectual Disabilities, 7, 283–294. doi:10.1111/
their inclusion into the mainstream of life. Through- j.1741-1130.2010.00278.x
out these future endeavors, and as our understanding Carroll, J. B. (1993). Human cognitive abilities: A survey of factor-
of the construct of ID continues to evolve, both the analytic studies. Cambridge, UK: Cambridge University Press.
doi:10.1017/CBO9780511571312
presence and legacy of Professor Emeritus Trevor DeKraai, M. (2002). In the beginning: The first hundred years
Parmenter will be most evident. (1850 to 1950). In R. L. Schalock (Ed.), Out of darkness and
into the light: Nebraska’s experience with mental retardation (pp.
Declaration of interest: The author report no con- 103–122). Washington, DC: American Association on Mental
flict of interest. The author alone is responsible for Retardation.
DePoy, E., & Gilson, S. F. (2004). Rethinking disability: Principles
the content and writing of the paper. for professional and social change. Belmont, CA: Thomson
Brooks/Cole.
Devlieger, P. (2003). From “idiot” to “person with mental retar-
References dation”: Defining differences in an effort to dissolve it. In P.
Devlieger, R. Rusch, & D. Pfeiffer (Eds.), Rethinking disability:
Alverson, C. Y., Bayliss, C., Naranjo, J. M., Yamamoto, S. H., & The emergence of new definitions, concepts and communities (pp.
Unruh, D. (2006). Methods for conducting post-school outcomes 169–188). Antwerp, Belgium: Garant.
follow-up studies: A review of the literature. Eugene, OR: National Devlieger, P., Rusch, F., & Pfeiffer, D. (Eds.). (2003). Rethinking
Post-School Outcomes Center, University of Oregon. disability:The emergence of new definitions, concepts and communi-
American Psychiatric Association. (2000). Diagnostic and statisti- ties. Antwerp, Belgium: Garant.
cal manual of mental disorders (4th ed., text rev.). Washington, Emerson, E., Fujiura, G. T., & Hatton, C. (2007). International
DC: Author. perspectives. In S. L. Odom, R. H. Horner, M. E. Snell, & J.
 236 R. L. Schalock

Blacher (Eds.), Handbook of developmental disabilities (pp. 593– Luckasson, R., & Reeve, A. (2001). Naming, defining, and classifying
613). New York, NY: The Guilford Press. in mental retardation. Mental Retardation, 39, 47–52.
Emerson, E., Graham, H., & Hatton, C. (2006). The measure- doi:10.1352/0047-6765(2001)039 ⬍ 0047:NDACIM ⬎ 2.0.CO;2
ment of poverty and socioeconomic position in research McConkey, R., & O’Toole, B. (1995). Towards the new millen-
involving people with intellectual disability. In L. M. Glidden nium. In B. O’Toole & R. McConkey (Eds.), Innovations in
(Ed.), International review of research in mental retardation (Vol. developing countries for people with disabilities (pp. 3–14). Lan-
32, pp. 77–108). New York, NY: Academic Press. cashire, UK: Lisieux Hall.
Emerson, E., & Hatton, C. (2008). Self-reported well-being of Medicode. (1998). International classification of diseases (9th rev.):
women and men with intellectual disabilities in England. Clinical modification (6th ed.). Salt Lake City, UT: Medicode.
American Journal on Mental Retardation, 113, 143–155. Mercier, C., Saxena, S., Lecomte, J., Cumbrera, M. G., & Har-
doi:10.1352/0895-8017(2008)113[143:SWOWAM]2.0.CO;2 nois, G. (2008). WHO Atlas on global resources for persons
Felce, D. (2006). What is mental retardation? In H. N. Switzky with intellectual disabilities 2007: Key findings relevant to
& S. Greenspan (Eds.), What is mental retardation? Ideas for an low- and middle-income countries. Journal of Policy and Prac-
evolving disability in the 21st century (Rev. and updated ed., pp. tice in Intellectual Disabilities, 5, 81–88. doi:10.1111/j.1741
xiii–xiv). Washington, DC: American Association on Mental -1130.2008.00152.x
J Intellect Dev Dis Downloaded from informahealthcare.com by Manukau Institute of Technology on 10/07/14

Retardation. Montreal Declaration. (2004). Montreal declaration on intellectual

Finlay, W. M. L., & Lyons, E. (2005). Rejecting the label: A social disability. Montreal, Canada: PAHO/WHO Conference on
constructionist analysis. Mental Retardation, 43, 120–134. Intellectual Disability.
doi:10.1352/0047-6765(2005)43 ⬍ 120:RTLASC ⬎ 2.0.CO;2 Nagi, S. Z. (1991). Disability concepts revisited: Implications for
Gardner, H. (1998). Are there additional intelligences? The case prevention. In A. M. Pope & A. R. Tarlov (Eds.), Disability in
for naturalist, spiritual, and existential intelligences. In J. Kane America: Toward a national agenda for prevention (pp. 309–
(Ed.), Education, information, and transformation: Essays in 327). Washington, DC: National Academy Press.
learning and thinking (pp. 111–132). Englewood Cliffs, NJ: Naglieri, J. A., & Das, J. P. (1997). Cognitive assessment system:
Prentice Hall. Interpretative handbook. Itasca, IL: Riverside.
Gardner, J. F., & Carran, D. T. (2005). Attainment of personal Oliver, M. (1996). Understanding disability: From theory to practice.
outcomes by people with developmental disabilities. Mental Basingstoke, UK: Palgrave Macmillan.
Retardation, 43, 157–174. doi:10.1352/0047-6765(2005)43 Parmenter, T. R. (2004). Contributions of IASSID to the scien-
[157:AOPOBP]2.0.CO;2 tific study of intellectual disability: The past, the present, and
Gottfredson, L. S. (1997). Mainstream science on intelligence: An the future. Journal of Policy and Practice in Intellectual Disabili-
For personal use only.

editorial with 52 signatories, history, and bibliography [Editorial]. ties, 1, 71–78. doi:10.1111/j.1741-1130.2004.04011.x
Intelligence, 24, 13–23. doi:10.1016/S0160-2896(97)90011-8 Powers, L., Dinerstein, R., & Holmes, S. (2005). Self-advocacy,
Greenspan, S. (2003). Mental retardation: Some issues for self-determination, and social freedom and opportunity. In K.
concern. In H. N. Switzky & S. Greenspan (Eds.), What C. Lakin & A. Turnbull (Eds.), National goals and research for
is mental retardation? Ideas for an evolving disability (pp. 64–74). people with intellectual and developmental disabilities (pp. 257–
Washington, DC: American Association on Mental 287). Washington, DC: American Association on Mental
Retardation. Retardation.
Greenspan, S., & Switzky, H. N. (2003). Lessons learned from Putnam, M. (2005). Conceptualizing disability: Developing a
the Atkins decision in the next AAMR manual. In H. N. Swit- framework for political disability identity. Journal of Disability
zky & S. Greenspan (Eds.), What is mental retardation? Ideas Policy Studies, 16, 188–198. doi:10.1177/1044207305016003
for an evolving disability in the 21st century (pp. 283–302). Wash- 0601
ington, DC: American Association on Mental Retardation. Rapley, M. (2004). The social construction of intellectual disability.
Hahn, H., & Hegamin, A. P. (2001). Assessing scientific measures Cambridge, UK: Cambridge University Press. doi:10.1017/
of disability. Journal of Disability Policy Studies, 12, 114–121. CBO9780511489884
doi:10.1177/104420730101200209 Rioux, M. H. (1997). Disability: The place of judgement in a
Heber, R. (1959). A manual on terminology and classification in world of fact. Journal of Intellectual Disability Research, 41,
mental retardation [Monograph Supplement]. American Jour- 102–111. doi:10.1111/j.1365-2788.1997.tb00686.x
nal of Mental Deficiency, 64(2). Salamanca Statement. (1994). Salamanca statement and framework
Heber, R. (1961). A manual on terminology and classification on for action in special needs education. Paris, France: UNESCO,
mental retardation (2nd ed.) [Monograph Supplement]. Wash- Ministry of Education and Science, Spain.
ington, DC: American Association on Mental Deficiency. Schalock, R. L. (1999). The merging of adaptive behavior
Horn, J. L., & Cattell, R. B. (1966). Refinement and test of the and intelligence: Implications for the field of mental retarda-
theory of fluid and crystallized general intelligences. Journal of tion (pp. 43–60). In R. L. Schalock (Ed.), Adaptive behavior
Educational Psychology, 57, 253–270. doi:10.1037/h0023816 and its measurement: Implications for the field of mental retarda-
Institute of Medicine. (1991). Disability in America: Toward a tion. Washington, DC: American Association on Mental
national agenda for prevention. Washington, DC: National Acad- Retardation.
emy Press. Schalock, R. L. (2004). The emerging disability paradigm and its
Isaacs, B. J., Brown, I., Brown, R. I., Baum, N., Myerscough, T., implications for policy and practice. Journal of Disability Policy
& Neikrug, S., … Wang, M. (2007). The international family Studies, 14, 204–215. doi:10.1177/10442073040140040201
quality of life project: Goals and description of a survey tool. Schalock, R. L. (2006). Scientific and judgmental issues involved
Journal of Policy and Practice in Intellectual Disabilities, 4, 177– in defining mental retardation. In H. N. Switzky & S. Green-
185. doi:10.1111/j.1741-1130.2007.00116.x span (Eds.), What is mental retardation? Ideas for an evolving
Luckasson, R., Borthwick-Duffy, S., Buntinx, W. H. E., Coulter, disability in the 21st century (Rev. and updated ed., pp. 231–
D. L., Craig, E. M., Reeve, A., … Tasse, M. (2002). Mental 245). Washington, DC: American Association on Mental
retardation: Definition, classification, and systems of supports (10th Retardation.
ed.). Washington, DC: American Association on Mental Retar- Schalock, R. L. (2010). International perspectives on intellectual
dation. disability. In K. D. Keith (Ed.), Cross-cultural psychology:
 What is intellectual disability? 237

Contemporary themes and perspectives (pp. 312–328). New York, Switzky & S. Greenspan (Eds.), What is mental retardation?
NY: Wiley-Blackwell. Ideas for an evolving disability in the 21st century (Rev. and
Schalock, R. L., Bonham, G. S., & Verdugo, M. A. (2008). The updated ed., pp. 247–266). Washington, DC: American Asso-
conceptualization and measurement of quality of life: Implica- ciation on Mental Retardation.
tions for program planning and evaluation in the field of intel- Sternberg, R. J. (1988). The triarchic mind: A new theory of human
lectual disabilities. Evaluation and Program Planning, 31, intelligence. New York, NY: Penguin.
181–190. doi:10.1016/j.evalprogplan.2008.02.001 Summers, J. A., Poston, D. J., Turnbull, A. P., Marquis, J., Hoff-
Schalock, R. L., Borthwick-Duffy, S. A., Bradley, V. J., Buntinx, man, L., Mannan, H., & Wang, M. (2005). Conceptualizing and
W. H. E., Coulter, D. L., Craig, E. M., … Yeager, M. H. measuring family quality of life. Journal of Intellectual Disabilities
(2010). Intellectual disability: Definition, classification, and Research, 49, 777–783. doi:10.1111/j.1365-2788.2005.00751.x
systems of supports (11th ed.). Washington, DC: American Switzky, H. N., & Greenspan, S. (2006). Summary and conclu-
Association on Intellectual and Developmental Disabilities. sion: Can so many diverse ideas be integrated? Multiparadig-
Schalock, R. L., & Luckasson, R. (2004). American Association matic models of understanding mental retardation in the 21st
on Mental Retardation’s definition, classification, and systems of century. In H. N. Switzky & S. Greenspan (Eds.), What is
supports and its relation to international trends and issues in mental retardation: Ideas for an evolving disability in the 21st cen-
J Intellect Dev Dis Downloaded from informahealthcare.com by Manukau Institute of Technology on 10/07/14

the field of intellectual disabilities. Journal of Policy and tury (Revised and updated ed., pp. 341–358). Washington,
Practice in Intellectual Disability, 1, 136–146. doi:10.1111/ DC: American Association on Mental Retardation.
j.1741-1130.2004.04028.x Thompson, J. R., Bradley, V. J., Buntinx, W. H. E., Schalock, R.
Schalock, R. L., Luckasson, R. A., & Shogren, K. A. (with Borth- L., Shogren, K. A., Snell, M. E., & Wehmeyer, M. L. (with
wick-Duffy, S., Bradley, V., Buntinx, W. H. E., Coulter, D. L., Borthwick-Duffy, S., Coulter, D. L., Craig, E. M., Gomez, S.
Craig, E. M., Gomez, S. C., … Yeager, M. H.) (2007). The C., Lachapelle, Y., Luckasson, R. A., … Yeager, M. H.) (2009).
renaming of Mental Retardation: Understanding the change to Conceptualizing supports and the support needs of people
the term intellectual disability. Intellectual and Developmental with intellectual disability. Intellectual andDevelopmental Disa-
Disabilities, 45, 116–124. doi:10.1352/1934-9556(2007) bilities, 47, 135–146. doi:10.1352/1934-9556-47.2.135
45[116:TROMRU]2.0.CO;2 Thompson, J. R., & Wehmeyer, M. L. (2008). Historical and legal
Schalock, R. L., & Verdugo, M. A. (2002). Handbook on quality of issues in developmental disabilities. In H. P. Parette & G. R.
life for human service practitioners. Washington, DC: American Peterson-Karlan (Eds.), Research-based practices in developmen-
Association on Mental Retardation. tal disabilities (2nd ed., pp. 13–42). Austin, TX: ProEd.
Schalock, R. L., & Verdugo, M. A. (in press). A leadership guide to United Nations. (2006). Convention on the rights of persons with
For personal use only.

redefining intellectual and developmental disability organizations: disabilities. Retrieved June 6, 2010, from http://www.un.org/
Eight successful change strategies. Baltimore, MD: Brookes. disabilities/convention
Schalock, R. L., Verdugo, M. A., Bonham, G. S., Fantova, F., & Van Loon, J. (2008). Aligning quality of life domains and indica-
van Loon, J. (2008). Enhancing personal outcomes: Organi- tors with SIS data. In R. L. Schalock, J. R. Thompson, & M.
zational strategies, guidelines, and examples. Journal of Policy J. Tassé (Eds.), Relating Supports Intensity Scale information to
and Practice in Intellectual Disabilities, 5, 276–285. doi:10.1111/ individual service plans (pp. 10–13). Retrieved from http://
j.1741-1130.2007.00135.x www.siswebsite.org/cs/SISwhitepaper/Individualserviceplans
Schroeder, S. R., Gerry, M., Gertz, G., & Velazquez, F. (2002). Vehmas, S. (2004). Ethical analysis of the concept of disability.
Final project report: Usage of the term “mental retardation”: Lan- Mental Retardation, 42, 209–222. doi:10.1352/0047-
guage, image and public education. Lawrence, KS: Kansas Uni- 6765(2004)42 ⬍ 209:EAOTCO ⬎ 2.0.CO;2
versity Center on Developmental Disabilities. Walker, S. P., Wachs, T. D., Gardner, J. M., Lozoff, B., Wasserman,
Senge, P. M. (2006). The fifth discipline: The art and practice of the G. A., Pollitt, E., … the International Child Developmental
learning organization (Rev. ed.). New York, NY: Doubleday. Steering Group. (2007). Child development: Risk factors for
Shogren, K. A., Bradley, V. J., Gomez, S. C., Yeager, M. H., & adverse outcomes in developing countries. Lancet, 369, 145–
Schalock, R. L. (with Borthwick-Duffy, S., Buntinx, W. H. E., 157. doi:10.1016/S0140-6736(07)60076-2
Coulter, D. L., Craig, E. M., Lachapelle, Y., Luckasson, R. A., Walter, A. I., Helgenberger, S., Wiek, A., & Scholz, R. W. (2007).
… Wehmeyer, M. L.) (2009). Public policy and the enhance- Measuring societal effects of transdisciplinary research
ment of desired public policy outcomes for persons with intel- projects: Design and application of an evaluation model. Eval-
lectual disability. Intellectual and Developmental Disabilities, 47, uation and Program Planning, 30, 325–338. doi:10.1016/j.
307–319. doi:10.1352/1934-9556-47.4.307 evalprogplan.2007.08.002
Shogren, K. A., & Turnbull, H. R. (2010). Public policy and out- Wehmeyer, M. L., Buntinx, W. H. E., Lachapelle, Y., Luckasson,
comes for persons with intellectual disability: Extending and R. A., Schalock, R. L., & Verdugo, M. A. (with Borthwick-
expanding the public policy framework of the 11th edition of Duffy, S., Bradley, V., Craig, E. M., Coulter, D. L., Gomez,
Intellectual Disability: Definition, Classification, and Systems of S. C., Reeve, A., … Yeager, M. H.) (2008). The intellectual
Supports. Intellectual and Developmental Disabilities, 48, 375– disability construct and its relation to human functioning.
386. doi:10.1352/1934-9556-48.5.375 Intellectual and Developmental Disabilities, 46, 311–318.
Shogren, K. A., Wehmeyer, M. L., Buchanan, C. L., & Lopez, S. doi:10.1352/2008.46:311–318
J. (2006). The application of positive psychology and self-de- World Health Organisation. (1993). International statistical clas-
termination to research in intellectual disability: A content sification of diseases and related health problems (10th ed.).
analysis of 30 years of literature. Research & Practice for Persons Geneva, Switzerland: Author.
with Severe Disabilities, 31, 338–345. World Health Organisation. (2001). International classification of
Simeonsson, R. J., Granlund, M., & Bjorck-Akersson, E. (2006). functioning, disability and health:ICF. Geneva, Switzerland:
The concept and classification of mental retardation. In H. N. Author.