Intellectual Disability

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Bob Schalock Interview

Robert Shalock, PhD, Professor Emeritus and former Psychology Chair, Hastings College, Hastings, Nebraska, talks about the 2010 AAIDD Definition Manual, with an overview of the latest thinking on definitions, terminology, assessment, and supports.

Question: As you were the Chair of the AAIDD Terminology and Classification Committee, let me start by asking you what work went into putting together the 11th edition of the AAIDD manual on intellectual disability.

R. S.: AAIDD has had a long history of being the authoritative source in the diagnosis and classification of people with intellectual disability.  For four years, it’s been my pleasure to chair the Terminology and Classification Committee. Our charge was to do an update of the 1992 and 2002 manuals. We have done that within the context of a tremendous international effort. The 18 members of the committee include three international members. My role was to coordinate their efforts as we focused on two major activities over a four-year period. First, we spent considerable time studying the reviews and critiques that had been done on both the 1992 and 2002 manuals. Second, during that four-year period, we published five articles that allowed us to update the literature in the respective areas and share our thoughts and proposals in regard to the 11th edition of the manual with the field. 
Through those articles we were able to consolidate the best thinking in the world about the condition of intellectual disability. As a result, we have produced a product that not only clarifies some of the points we made in the 1992 and 2002 manuals but also gives us increased consistency in the concepts and the terms we use in the 11th edition.

Question: For people familiar with the 10th edition of the manual, why should they read this 11th edition?

R.S.: We have tried to respond to the general population’s interest in this field, as well as the interests and needs of professionals.  It’s important to realize that the field of intellectual disability has gone though major shifts related to both our conception of disability and to how we view supports. We’ve moved away from defectology to an ecological or socio-ecological conception wherein we view the individual’s relation to his/her environment, realizing that it is not just the person but it’s also the environment that greatly impacts our behavior.

So for a start, the 11th edition describes why intellectual disability is a much better term to use. And we spend a lot of time on this because terminology is very, very critical. The term we use to refer to a condition, a person, or a phenomenon not only expresses and reflects expectations about that person but also clearly communicates what we think about that person. If you refer to a person as a retardo or as an idiot, that communicates very strong things, as opposed to using “a person with intellectual disability” who has very specific support needs.

The other major shift concerns how we view supports and the critical role that supports play. We realize that the professional services that historically have been provided to people are only one kind of support, but the future is in systems of supports. So for the 11th edition, in addition to terminology, we address the question: What are the best practices in the field of intellectual disability in terms of diagnosis, classification, and systems of supports? One of the things we did in reference to those best practices of systems of supports was to look into the human performance technology literature. Rather than talk about a support for a person, we now talk about a system of supports for the individual—a change that is reflected in the title of the manual.

A system of supports can involve many things, such as policies and practices, incentives, prosthetics, cognitive supports, opportunities, natural supports, skills, and knowledge.
So, as we have moved away from a singular focus upon “a support” to “a system of supports,” I think we’ve really broadened the reasons why individuals might be interested in reading and using the manual.

In addition, we’ve really tried to involve the international community. The 10th edition has been translated into 13 languages. And we’ve already signed contracts with at least five countries to translate the 11th.  So we’re not talking about a US-based population; we are really talking about the international community. As we interact with the international community, we’re very sensitive to the needs of individuals in both developed and developing countries, and we have tried to tailor our suggestions and recommendations with that in mind.

Finally we’ve added some significant material in terms of policy and practice. There’s a very extensive chapter that looks at the impact of the 11th edition on public policy, and for the very first time, we look at the policy implications in terms of outcomes for individuals and their families.

So in the 11th edition, we are not only talking about the diagnosis classification and about systems of supports for persons with intellectual disability, we are also focusing on personal and family-related outcomes.

Question: We hear a lot about the AAIDD system being supports-based. Can you tell us why this system allows for a more progressive view of intellectual disability?

R.S.: The 2010 definition is not only a supports-based definition; it also reflects the current thinking about what disability is and, more specifically, what intellectual disability is. I think it’s important for people to realize that we are using the same definition that appears in the 2002 manual with the insertion of the term intellectual disability in place of the older term mental retardation.

There are good reasons why we moved away from that term, mental retardation. It’s an old and pejorative term that really does not reflect the social-ecological conception of disability that is now current in the world and is very much reflected in the names of organizations and journals throughout the world.

So before I talk about why this is a supports-based definition, it’s important to understand the definition itself. Again, this is the definition that is being used throughout much of the world, and it is one that we anticipate will continue to be used because it does reflect current thinking.

Intellectual disability is characterized by significant limitations both in intellectual functioning and in adaptive behavior as expressed in conceptual, social, and practical adaptive skills. This disability originates before the age of 18.

Now a definition is a definition. One of the points that we introduced in 1992 was that a definition does not stand by itself. Thus, we have stressed the need to understand the assumptions that underlie a definition. Assumptions are an explicit part of the definition because they clarify the context from which the definition arises and indicate how the definition must be applied. Since the 1992 manual, we have promulgated a series of five assumptions that reflect where the definition comes from and provide a strong recommendation as to how it should be applied. The five assumptions are as follows:

  • Limitations in present functioning must be considered within the context of community environments typical of the individual’s age peers and culture. This assumption contextualizes what intellectual disability is.
  • Valid assessment considers cultural and linguistic diversity as well as differences in communication, sensory, motor, and behavioral factors.
  • Within an individual, limitations often coexist with strengths.

The final two assumptions deal with supports and make this a very unique definition:

  • An important purpose of describing limitations is to develop a profile of needed supports. This assumption is so critical because very often people just make a diagnosis and that ends process. What we stress is that the diagnostic process must include the planning of individual supports as a key part of that process.
  • With appropriate personalized supports over a sustained period, the life functioning of a person with intellectual disability generally will improve. I think the importance of this assumption is self-evident.  This assumption results in the need to consider the whole individual and not just the person’s limitations. The intent of personalized supports is to enhance the level of human functioning.

Question: Can you talk about the role of IQ and about the issues professionals face in assessing intelligence in the book?

R.S.: In the history of intellectual disability, we have continually grappled with the issue of IQ. . Ever since our definition in the 1992 manual, we have tried to give equal consideration—and advocated for giving equal weight—to limitations in intellectual functioning and limitations in adaptive behavior.

In terms of IQ (we prefer to use the term intellectual functioning) I think it’s important to understand how we approach intelligence. There are a number of approaches in the literature. Some people talk about multiple intelligences, but the general consensus in the field is that is that intelligence is a general mental ability. We talk about the importance of understanding both multiple intelligences and the general concept of intelligence. But the multiple intelligence concept does not have good measures associated with it. So the strongest measure of a person’s intellectual functioning is still an individually administered intelligence test and the resultant IQ score.

So once one understands what intelligence is and how one assesses it, we address some of the real issues. For example, how low an intelligence score do you need in order to be considered an individual with intellectual disability? So we talk about the concept of a cut-off score, which is an IQ score that is approximately two standard deviations below the mean. The mean of an IQ test is 100; two standard deviations would be give score of approximately 70.

But that’s only one concept that we talk about in terms of the issues that need to be addressed in intelligence testing and interpretation. In addition to the cut-off score, there is also the concept of standard error of measurement, which recognizes that whenever you measure any behavior, there’s going to be error involved in the measurement. The error may involve the technique you use, the environment in which you do the administering, the skills of the administrator, or the responsivity of the individual.

Therefore, any test of intelligence has a standard error of measurement associated with it.  For most of the individually standardized tests of intelligence, that standard error of measurement is between three and five points.

So overall, we have the two standard deviations below the mean regarding the cut-off score, as well as the three to five points related to the standard error measurement. These two scores then are used to establish the confidence interval within which the person’s true IQ score falls.

The 2010 manual talks about two confidence intervals. One is referred to as the 66-percent confidence interval, which means you use one standard error of measurement; the other is the 95-percent confidence interval in which you have two standard errors of measurement. So, for example, for most individuals who achieve an IQ score of 50, their true score may well be somewhere between approximately 40 and 60 if one uses the 95% confidence interval (or standard error of estimate).

The confidence interval you use really depends upon the question that is asked, the importance of the decision that is made, and the ultimate strengths and weaknesses of the respective intelligence tests. Clinical judgment is involved in this decision making, and the topic of clinical judgment is covered extensively in Chapter 8 of the 2010 manual.

Question: We read a lot about the issue of classification in this edition of the AAIDD manual, perhaps more so than in previous editions. Why this emphasis on classification as much as on the process of diagnosing intellectual disability?

R.S.: The issue of classification has both a historical dimension and a very pragmatic current dimension. Historically, people have been diagnosed with intellectual disability or what was previously called mental retardation or mental deficiency, and then they have been classified based upon an IQ score. Historically, those individuals were classified as mild, moderate, severe, profound, or moron, idiot, etc., based upon an IQ score.

Beginning in the 1992 manual and continuing in 2002 and now in the 2010 manual, we have recognized that the world is changing in reference to the kinds of questions that are being asked regarding people with intellectual disability. We now are asking questions like, is this person competent to be a witness? Is this person competent to be a self-advocate? Is this person competent to be a parent? Is this person competent to have sexual relations? Is this person competent to have a bank account?

When competency comes into play, the old historical notion of a classification based only on an IQ score really falls to the wayside. So, beginning with the 1992 manual and continuing now through the 2010, we have suggested that since the questions that we’re asking people are changing, and since the world is changing in terms of expectations that we have for people with intellectual disability, then our classification system must indeed reflect that changing world.

What we do in to 2010 manual, consistent with the 2002 version, is that we have a multi-dimensional model of human functioning, which looks at what we call the five dimensions of human functioning:  intellectual functioning, adaptive behavior, health, participation, and context.

What we do then in the 2010 manual (which we did not do in the 2002 manual) is to propose a classification system that is based upon these multi-dimensions of human functioning. Such a multidimensional classification system allows one to classify depending upon the questions asked and the purpose of the classification system. Although researchers generally prefer the historical classification system based upon intellectual functioning, we stress in the 2010 manual that one can also classify on the basis of adaptive behavior heath, participation, and/or context.

Then we add an additional component to that multidimensional classification system: supports. Through the Supports Intensity Scale (SIS), we now have a way to measure the pattern and intensity of support needs of people. Because that information is now available, we can classify people based upon their support needs. And this is exactly what’s happening as the SIS is being used throughout the world for multiple purposes, including resource allocation. 
To permit the reader to understand the important relationships among diagnosis, classification, and developing individualized supports, in the 2010 manual we introduce an assessment framework, which we related to three clinical functions: diagnosis, classification, and planning individualized supports.

The point that we make is that these three clinical functions need to be aligned. You diagnose for a purpose, you classify for a purpose, and then you use that information to plan individualized support.

Question:  As you know, the Supports Intensity Scale is now being used in the United States and in other countries. The AAIDD Diagnosis, Classification, and Systems of Supports Manual and SIS share the same philosophical origin of looking at the needs of people with intellectual disability to enhance their condition.  How do the two tie in at a practical level for professionals in developmental disability?

R.S.: It’s increasingly apparent that the definition of intellectual disability (and the assumptions that accompany it) must include the concept of supports. And the reason this is so critical is because the level of human functioning of any of us is directly related to the supports that we receive. So when you stop focusing only on the defect that the individual has and look instead at what is the potential of the person in regard to human functioning with the appropriate supports, then you really have a complete system. Internationally, you see supported employment, supported living, and supported education. The vehicle that has allowed the alignment of the diagnosis and classification and supports process has been the SIS.

As we define intellectual disability, we need to think not only about the definition but also about the assumptions that underlie the implications and the implementations of the definition. You cannot simply take that definition in isolation. You must include the assumptions, two of which deal directly with supports. What we want to see people do—which is a best practice—is to go beyond the world of diagnosis: to understand not just the implications of your diagnosis but also what needs to be done once an individual is diagnosed as an individual with intellectual disability. Until recently (and with the availability of the SIS) people used the person’s level of adaptive behavior as a basis for planning. For example, historically, you use the SIS.

The person’s pattern of scores on an adaptive behavior scale was used to develop both rehabilitation plans and goals and educational plans and goals. It was not used not as part of diagnosis. Since 1959, and certainly since the 1992 manual, adaptive behavior has become co-equal with intelligence in terms of the criteria for intellectual disability.

But since the 1992 manual and more recently, with data from the SIS as the vehicle to develop support plans, we have developed plans that are based upon an individual’s support needs as opposed to their adaptive behavior. This change has profound impacts. For example, when you focus on adaptive behavior in individual education plans or individual program plans, what emerges is the concept of behavioral objectives. These are infamous. A behavioral objective is an objective you have for the person to do something: They put on their clothes with minimal assistance or complete assistance, or they perform this act correctly 50 percent of the time or 70 percent of the time.  The problem with behavioral objectives is that the focus is on what the person does or does not do, and it’s the person’s responsibility or the person’s fault if that behavior does not occur.

Once you shift to a supports focus, it becomes a support objective, which is something that is our responsibility as professionals or as individuals who work with that person to provide.  So what are increasingly monitored in an individual program plan or an individual supports plan are not behavioral objectives but individual support objectives to see whether or not that support is actually provided. We know that if a support is provided, the behavioral change is very likely to occur.

Question: What was the process of everybody’s work putting this edition together?

R.S.: It was an honor and a pleasure for me to basically be both a coach and a mediator of 18 people. These 18 people became involved in the process by invitation. They represent a myriad of disciplines, they are both national and international, and they all are experts in their field. They came to the committee and to our deliberations from very different perspectives. Over the course of four years, we worked via monthly telephone conference calls, a number of face-to-face meetings, and at least a million emails,

Our challenge was to build on the strength of the 1992 and 2002 manuals. In deciding how to do that, we had to make some critical decisions, such as, how much do we deviate from that which we’ve already done? Very early in our deliberations, we decided that we would not deviate significantly from the 2002 definition of what was then mental retardation but which is now intellectual disability. That definition had become very important. It is now embodied in a number of Supreme Court cases and a number of significant litigations, as well as in the mainstream of best practices. 

Our next critical decision was to decide on what form the manual would take: a handbook, a workbook, a manual? Each of those formats raises different questions of presentation and approach. We decided to stay with the manual format.

Our third major decision concerned how to update ourselves. This issue was considered from many perspectives: medical, psychiatric, legal, special education, physiological, and providers’. The suggestion we followed was to develop work teams that would be responsible for very specific areas.  As a result, we published five articles covering terminology, naming, the construct of intellectual disability, individuals with higher IQs, the supports paradigm, and public policy.