Intellectual Disability

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Marti Snell, PhD, Professor, Curry School of Education, University of Virginia, Charlottesville, talks about the 2010 AAIDD Definition Manual and its application to special education.

Question: What is in the AAIDD definition manual for special education teachers?

M.S.: The New AAIDD definition manual has a number of things that are valuable to special education teachers. One is the definition itself and the fact that we’re now using the term intellectual disabilities rather than mental retardation. Also, there is a very detailed description of that diagnostic process, which is important for teachers to understand, particularly in terms of eligibility for special education.

The chapter on education includes a five-step process for designing education plans, a process that reinforces the notion of identifying supports that students need in order to achieve their outcomes and their individualized educational plan. Characteristics of educational practices are also described in that chapter.

Finally, there’s a chapter that addresses individuals with intellectual disabilities who have higher IQs. That’s a new addition, and I think that gives more depth to the current research on these individuals and their situation in society—in many cases their poverty, their not finishing school, and their lack of jobs. Not only does the chapter demonstrate some of the difficulties that many of these individuals are in, but it also offers some description on their ways of making social responses and how that sometimes gets them into trouble. I think this chapter gives some valuable details that are quite relevant to teachers.

Question: How is the AAIDD definition manual useful for professionals in special education, such as special education teachers and school psychologists?

M. S.: The AAIDD manual is particularly useful for school psychologists because it provides a lot of detail on the diagnostic process, the purposes for assessment, and the tools that one would use to achieve those purposes. It provides some of the most current knowledge that we have on accurate assessment and diagnosis of intellectual disabilities.

In terms of education, there is a chapter on supports that addresses the whole notion of supports, how you identify needed supports, and how you can take needed supports and combine them with a student’s individualized educational program. That’s particularly relevant to special educators but also to members of the educational team.

I think parents would benefit greatly from having access to the chapters at the beginning of the manual that deal with the diagnosis of intellectual assessment. This would help them to better understand the assessments that are being done with their child, the decisions that are being made, and the rules for making those decisions.

I think adult service providers and legal professionals would also find some value both in the diagnostic chapters and in the new chapter on individuals with intellectual disabilities and higher IQs. This latter chapter was not included in prior manuals and it provides some current information on their life situation, particularly in the United States:  their vulnerabilities and needs, as well as some of their challenges involving denial of the disability, attempts to pass as nondisabled, gullibility, suggestibility, desire to please, and naïveté. Some individuals have many of these characteristics, which can cause problems for them.

Question: You mention that school psychologists are most likely to use the information in the AAIDD definition manual, as they are responsible for determining eligibility for special education services. Can you elaborate?

M. S.:  More than any other set of professionals, school psychologists are probably most likely to use the information in the AAIDD definition manual because their role is to determine eligibility for special education services and eligibility for the diagnosis of intellectual disability.

The initial eight chapters in the manual address diagnosis. They address how the definition is applied, what IQ and adaptive behavior measures are used and how they are used, and how the measurement results are interpreted and understood. These chapters provide some in-depth guidelines for clinical psychologists to apply in determining whether or not a diagnosis of intellectual disability is appropriate.

While these chapters address issues that prior manuals also addressed, what is relevant is that they update very accurately what we know about diagnosis. These chapters on intellectual ability and adaptive behavior assessment are very current and provide excellent guidelines for psychologists. They address, for example, elements that psychologists do not universally apply but should apply when diagnosing intellectual disability, such as the use of standard deviations, the use of standard error of the mean, and the notion of correcting scores on older tests given the predictable increase in the population mean (known as the Flynn Effect).

Question: For years, special education students were grouped according to their “levels of mental retardation.” The AAIDD definition system is multidimensional and supports-based and not based on IQ ranges.  How does this system challenge professionals to think differently about intellectual disability and how does it affect educational practices?

M.S.: The current AAIDD manual challenges us to think about intellectual disability in a number of different ways.  For a start, the four traditional ways of classifying individuals with intellectual disability by their IQ has led to the practice of separating people into groups. We used to use—and unfortunately often still use—the terms mild, moderate, severe, and profound as the descriptors for grouping special education students.  These terms were very much influenced by the definition of the disability. We find that schools will have classrooms that use these same group labels to serve students at different IQ levels. The past tradition was to sort students with intellectual disability by their IQ level and place them into separate classrooms; teachers endorsed to work with individuals identified by the same IQ level groups were then matched to students in those classrooms.

But this traditional approach has had some pretty bad effects on inclusion. Far more than any other disability group, students with intellectual disability have been separated from their peers who have no disabilities. For example, 51 percent of students with intellectual disabilities still spend the large majority—more than 60 percent—of their day away from peers who don’t have disabilities. In contrast, other disability groups spend about 18 percent of their day away from their non-disabled peers.  So we have a lot of segregation or separation of students because they have a label of intellectual disability.

The current manual challenges that approach by having educational teams work through a five-step process to identify goals, assess supports, and then to plan, monitor, and evaluate intervention. It purposely emphasizes the importance of supported inclusion of students and support-based means to identify student needs.

Step one: Often referred to as person-centered planning, this step is one that, unfortunately, teams rarely do. It could also involve what we call an ecological inventory. But the bottom line of this first step is that we are assessing needed, desired, and valued goals and life experiences.

Step two: Assessing the supports a person needs in order to reach and achieve those goals.

Step three: Writing an IEP (Individualized Educational Plan). At this step the parent and team members need to try to prioritize what’s most important for that individual. They also must identify the teaching methods, location, and necessary adaptations and the steps to implement the program.

Step four:  Monitoring to see if there has been progress.

Step five:  Evaluating the outcomes.

This five-step process doesn’t have to happen in a special education classroom. Supports are portable. And in the past I think we’ve relied way too much on saying you can only get supports if you’re in a special education classroom. The process takes a lot of time and energy, but it allows the students with intellectual disability to get the kinds of supports that they actually need.  Because this new manual provides a lot more detail on this process, it’s very helpful to teachers.

Finally, because this manual will help professionals think differently about intellectual disabilities and because it offers this five-step educational process, I think we will be better able to deal with the bad outcome statistics that we have for learners with intellectual disability. Individuals with intellectual disability have a very high dropout rate. The most current estimates are that 28.6 percent of individuals with intellectual disabilities drop out of school before they finish. There are a number of reasons. One seems to be that students may not be getting enough supports, or that the goals and the directions of their IEPs are not individualized. I think students become disillusioned if their educational program doesn’t have a functional, vocational component to it. Another reason for extensive dropout rates is the high degree of segregation. Students don’t like to be viewed as being different. The combination of these reasons contributes to this high dropout rate.

If educators can apply the supports-based system, we should be able to make a difference in the dropout rate.

Question: The Individuals with Disabilities Education Act (IDEA) and the AAIDD definition system—one does not tend to think of the two in the same context, but you point out that the two are intimately related in philosophy and practice. Can you elaborate?

M.S.: There are a lot of commonalities between the current federal law, IDEA, and the AAIDD definition system. First, both deal with the importance of providing supports to individuals, that is, you need to identify the supports an individual with intellectual disability should have and put them into place. Having appropriate educational supports is directly related to the achievement of an individual’s educational plan

Both IDEA and the current manual emphasize that supports are very broad. They can include people providing assistance—professionals such as related services staff:  occupational therapists, physical therapists, and speech and language pathologists. Supports also can include the provision of specialized instruction and also supervised work experiences; there’s a whole array of supports that need to be identified and matched to the student’s needs.

Another area of agreement is the importance of educating individuals with disabilities alongside non-disabled peers, that is, not separating them for their education.
The manual on intellectual disabilities also stresses the importance of inclusion.

And finally the law places great emphasis on accurate diagnosis of disability in terms of the process of finding someone eligible or not eligible for special education services. Likewise, the manual provides guidelines, the most current research-based guidelines, on how to diagnose intellectual disability.

Question: While talking about deciding what and how to teach students with intellectual disability, you say candidly, “There is no shame in implementing a teaching method that is not successful; but there is shame in continuing with teaching methods that are not successful.” Can you elaborate?

M.S.: This line is mentioned in the education chapter in the manual. It means that teachers and the other members of the educational team have a responsibility to put into place programs that work for students.

Now the challenge is that programs have many elements. Often educational programs for students with intellectual disabilities are delivered by a number of staff, professional and paraprofessional. You might need to simplify what the child is being taught, or make the objectives more logical for the individual student.  We often need to add adaptations, particularly for students with additional disabilities. So if an individual has a movement disability, vision, hearing, or communication disability in addition to the intellectual disability, we may need to add equipment or make adaptations in the teaching methods, or the materials. We may need to add specialized kinds of computers, manipulative teaching materials, large type, and so on.

Educational programs are complex. There are lots of different people who could teach the program, there are different materials involved, and there are different teaching methods. In order to know whether or not a student is learning, the teacher needs to collect periodic data (say once every week or every two weeks) on the student’s ability to perform the targeted skill. The only way to determine whether a program is actually working is to use those data to judge whether or not the student is learning.

Sometimes data will tell you that students are making nice progress; then the program is left in place. But more often than not, the team will look at the data and will see that the program could be improved in same way. So then the task is to try to figure out what to change.

Question: In a nutshell, what are the best practices in education that substantiate the impact of the AAIDD definition system of intellectual disability?

M. S.: The new AAIDD manual includes several best practices in special education, including these:

  • Educating students with intellectual disabilities must be done alongside their peers who don’t have disabilities. But at the same time, we need to have the necessary supports in place for their learning success.
  • A student’s educational team, including care providers, must aim for skills that they determine to be relevant for the individual student.
  • To make learning successful, we should provide the supports that have been identified as needed.
  • The skills that are taught need to be ones that are relevant at two points in life – now and in adulthood.


Question: For some historical perspective, can you comment on the process of gradual changes that resulted in the current definition, focus on supports, and change to the term intellectual disability? Were there any objections?

M. S.: In 1992 when AAMR first introduced the notion of supports, it shifted our thinking so that, instead of focusing on a level of deficiency, we should think in terms of individual profiles of needed supports. Different people have very different profiles.

At the time the idea was novel, and a lot of people didn’t like it. Then in 2002 with the 10th manual, we carried that idea a bit further. We adjusted the definition so that it was, I think, easier to use in terms of measurement, and we also expanded the notion of supports. In this latest 11th edition of the manual, we have continued with the idea that it’s absolutely critical to focus on identifying needed supports. It has been 17 years since we began the shift in focus to supports and away from deficiencies.

I see this focus on supporting people as a consistent message and a refinement of a message rather than some revolutionary change. I think over the past three editions there has been a gradual bringing of people into the fold or into the acceptance of support as a central element of intellectual disability. With the 11th edition of the manual, the goal is to reach a higher level of agreement about one of the latest big changes: the change from the term mental retardation to intellectual disability.

I think the notion of systems of support has a certain universality and has gained widespread acceptance.  It’s a more positive approach to view profiles of needed support rather than levels of deficiency. If you provide an individual with the supports that they actually need to achieve valued outcomes, the focus is on what they can learn and what they can do rather than on numbers of IQ points and what an individual cannot achieve.  

I think this turnaround is now widely accepted, as well as is the term intellectual disability. The term is very widely accepted across countries; in fact we were one of the last countries to really institute the term intellectual disability.

How did we do that? Well one thing that happened was we pretty much said, “Stop using mild, moderate, severe, and profound IQ levels to classify students in schools! Do not do that anymore!  Don’t classify kids by their IQ scores!”  We saw what happened in schools as a result of this practice. We saw that kids were being sorted out into groups depending on how much we predicted they could learn!  It was just a very bad system.

The change in terms met with a lot of reaction from researchers who said, “We want to continue to classify and report and to continue to describe people by their IQ levels.”
And so it really took awhile for both sides to come back to the table. Our approach was this: There are multiple ways to classify people with disabilities. You just need to have a purpose for doing so. And if your purpose is research, then you might choose to describe individuals by adaptive behavior levels, by support levels, or even by IQ levels. Fine. That’s a legitimate purpose. But it’s a mistake to let IQ levels dictate classrooms, separation, and predictions of what people can and can’t learn.

In the 1980s with the 8th manual on the definition of mental retardation, we were still very heavily into classifying people by IQ levels. And of course that approach has still not been eradicated. It’s still built into some laws and educational practices and is still used by many school systems. One bad side effect of classifying people by IQ and using the terms mild, moderate, severe, profound, is that this practice limits your expectations for what people can achieve.

In fact I can remember that the manual in the 1980s had a glossary in the back that used adaptive behavior descriptions; for each level – mild, moderate, severe, and profound – the glossary predicted the highest level of skill that could be achieved by individuals in that grouping. And that was a perfect example of pigeonholing people and basically preventing them from ever being able to arise above that skill level: You have this IQ; you will achieve this and no more.

You get the same pigeonholing outcome when using classrooms that have these general IQ labels on them: Educators, even parents, and others on the team and in the school, and people on the street tend to limit the potential of and the possibilities for students in those particular IQ-based classifications.

Question:  Finally, have you any further comments about your work on the AAIDD committee charged with bringing out this new manual?

M. S.: I think it’s been especially inspiring to work with this committee of people and to learn from them and to be able to toss ideas around, see our ideas kind of meld together, and learn from each other. Our interest has been in trying to make as clear as we can the process for diagnosing intellectual disability, so that it can be done carefully and accurately.

Another important element has been the interest that many committee members have in individuals with intellectual disabilities who are on death row; these are individuals who, because of their disability, are often victims within our legal system. The 11th edition manual provides clear guidelines for accurate diagnosis, even if completed retroactively.