Intellectually Disabled?..Or Not? Issues in the Definition of Mental

Retardation

Ellen M. Frye, Ed.D.April 8, 2010

TEDA ConferenceSouth Padre Island

Historical Perspective

• Early 20th century, 1906—introduction of first intelligence test by Alfred Binet

• 1912—Goddard published book on the Kallikak family attempting to demonstrate that intelligence & feeble-mindedness was hereditary

• Divided ‘feeble-minded into 3 classes– Idiots—mental age below child of 2 years

– Imbeciles—mental age of approximately 7 years

– Morons—mental age of approximately 12 years (coined the term ‘moron’)

Historical Perspective• 2006—changed to ‘American Association on

Intellectual and Developmental Disabilities’ (AAIDD)

• 1992—changed to ‘American Association on Mental Retardation’ (AAMR)

• Name later changed to ‘American Association on Mental Deficiency’ (AAMD)

• 1876—founding of oldest & largest organization of professionals working with persons with MR—Association of Medical Officers of American Institutions for Idiotic and Feeble-minded Persons (AMOAIIFP?)

This week, the U.S. House of Representatives passed Rosa’s Law, removing the term “mental retardation” from federal law and replacing it with “intellectual disability.” CEC applauds Congress for taking this small but important step to provide individuals with and without disabilities the healthy, respectful environment they deserve. The bill now goes to President Obama for his signature.

www.cec.sped.org, week of 9-22-2010Signed by President Obama on October 5, 2010

Definitions of Mental Retardation• 1961—AAMD criteria

– Intelligence score 1 SD below mean (below 85)– Used descriptors of ‘educable,’ ‘trainable,’ and

‘dependent’• Educable—capable of learning minimal academic

skills• Trainable—needed to learn personal care & social

adjustment rather than academics– First to require impairments in adaptive

behavior– Onset before age 16

Definitions of Mental Retardation

• 1961 AAMD criteria cont’d

– Dual categories used to reduce reliance on intelligence scores, eliminate false positives

• Adaptive behavior defined as ‘maturation, learning, or social adjustment’

• AAMD Adaptive Behavior scale developed to measure adaptive behavior

Definitions of Mental Retardation • 1973—intelligence criteria changed to 2 SDs below mean

(below 70)– Introduced ranges as mild, moderate, severe, &

profound– Also included concurrent low adaptive behavior scores– Extended developmental period to age 18

• 1977—allowed for persons with ‘borderline intelligence (intelligence scores of 70-80) to be identified as MR

• Scores 2 SDs below on Verbal & Nonverbal areas? (part of EHA/IDEA?)

1992/2002 AAMR CriteriaSignificantly sub-average intellectual functioning, existing concurrently with related limitations in 2 or more of the following applicable adaptive skill areas:

• Communication• Self-care• Home living• Social skills• Community use

• Self-direction• Health and safety• Functional academics• Leisure• Work

1992/2002 AAMR Criteria• Includes required onset before age 18 • ‘significantly sub-average intellectual functioning’ defined

as intelligence score of approximately 70 to 75 or below– Used standard error measurement to allow scores

between 70-75• Substituted descriptors of ‘mild,’ ‘moderate,’ and

‘severe,’ with levels of support needed to achieve optimal independence—’intermittent,’ ‘limited,’ ‘extensive,’ and ‘pervasive’

DSM-IV-TR Definition of MR• DSM-IV-TR (2000)Significantly subaverage intellectual

functioning: an IQ of 70 or below on an individually administered IQ test

Concurrent deficits or impairments in present adaptive functioning in at least 2 of following areas: communication, self-care, home-living, social/interpersonal skills, use of community resources, self-direction, functional academic skills, work, leisure, health, & safety

Onset before age 18 years

Current IDEA definitionIDEA 300.8(c) (6)Mental retardation means

significantly subaverage general intellectual functioning, existing concurrently with deficits in adaptive behavior and manifested during the developmental period, that adversely affects a child’s educational performance.

Current Texas interpretation of IDEA Definition

• Texas Administrative Code 89.1040 Eligibility Criteria

A. [student] has been determined to have significantly sub-average intellectual functioning as measured by a standardized, individually administered test of cognitive ability in which the overall test score is at least two standard deviations below the mean, when taking into consideration the standard error of measurement of the test; AND

Current Texas Interpretation of IDEA Definition

• B. Concurrently exhibits deficits in at least two of the following areas of adaptive behavior: communication, self-care, home living, social/interpersonal skills, use of community resources, self-direction, functional academic skills, work, leisure, and safety

Differences/Similarities• Texas/IDEA does not mention onset before age

18 yrs• Use overall intelligence score rather than verbal

& nonverbal scores• Texas/IDEA repeats same 10 areas of adaptive

behavior as AAIDD definition (DSM-IV-TR lists 11)

• Texas/IDEA requires deficits in at least 2 areas of adaptive behavior rather than overall adaptive behavior score

Concerns• AAIDD raises cut-off from intelligence score of 70 to

75

– Meant to include standard error measurement (SEM), but SEM not always 5 standard score points on current intelligence measures

– Can double number of students with mild MR due to ‘bump’ at end of bell curve

Concerns• Raising cut-off of intelligence score to 75

could double number of students identified as MR– Bulk of additional students seem to be

minority students– Minority students with intelligence scores

between 65-75 could easily be questioned• Professional judgment calls for documentation of

previous intelligence scores in similar ranges

Concerns• Current definitions increase number of

adaptive behavior areas– No adaptive behavior measures for areas

such as community use, self-direction, health & safety, leisure, functional academics, or work

– Student could have deficits in those areas and NOT in communication, daily living skills, and socialization

Flynn Effect• As time passes and intelligence test norms get older,

people perform better and better, raising the mean score by several points within a matter of years– Discovered in 1984– Occurs on intelligence tests in other countries, but in

some countries it has slowed– Stronger on tests of fluid intelligence (problem-

solving, abstract reasoning– Also occurs on achievement tests, probably adaptive

behavior measures, too• When tests are renormed, mean is set back at 100,

making the tests ‘harder’

Flynn Effect• Scores increase approximately .3 points per

year, resulting in @ 3-point gain 10 years after instrument is normed and 5-point gain 15 years post-norms

• Difference of 3-5 points can affect intelligence scores close to 70 cut-off

• Also, students who score outside MR range on instrument administered toward end of norms-life can fall within MR range when given instrument with newer norms

Flynn Effect—Why?• Are we really getting smarter?

– If trends are correct, working backwards, average intelligence of Americans early in 20th century was equal to current intelligence score of 70

• Are we better educated?– Probably, nowadays we teach students to think more

abstractly & scientifically– Earlier education curriculum emphasized rote

memory of concrete ideas rather than abstract thinking

• Result of more scientific & industrialized environment & society in general

Impact of Flynn Effect• More students identified as MR in years after

tests with newer norms come out• Students with borderline intelligence scores

may be ineligible for special education services if tested with instrument with older norms

• Students with borderline intelligence scores may be misidentified as MR if tested with newer instruments with newer (i.e. harder) norms

Impact of Flynn Effect

• Adaptive behavior scores can make difference between whether or not a student/person identified as MR

– Theoretically Flynn effect can also impact adaptive behavior scores

(have not found any literature on Flynn effect on adaptive behavior scores)

Additional Impact of Flynn Effect• Bulk of students/persons not eligible or

misidentified as MR tend fall into mild range• Students not eligible as MR sometimes ‘fall

through the cracks’ because required to take high-stakes tests, may not be allowed to graduate

• Students identified as MR may later be eligible for disability (SSI) benefits throughout lifetime

• Major issue for prisoners on death row due to Atkins v. Virginia Supreme Court case

WISC-IV• Use Full-Scale score

– Increased statistical sophistication since 1992 AAMR definition allowed for intelligence scores between 70 & 75

– SEM ranges from 2.6 to 3.0 depending on age of student• SEM of 3 at younger ages of 6-7 years

when scores tend to be more unreliable

Wechsler Non-Verbal

• Non-verbal measure of general g• Full Scale 4 SEM—ranges from 4.24 to 5.41• Full Scale 2 SEM—ranges from 3.67 to 6.0• Need to document reason for using

nonverbal measure of overall cognitive ability

Woodcock-Johnson 3-Cognitive• General Intellectual Ability from 7 Standard

subtests– May want to use Extended Battery depending

on previous scores in borderline range• SEM ranges from 2.12 to 3.0 for Standard

Battery• SEM ranges from 1.5 to 2.6 for Extended

Battery• BIA SEM ranges from 2.12 to 3.67 but use for

MR eligibility is questionable

Kaufman Assessment Battery for Children-2

• MPC—SEM ranges from 2.95 to 4.69 – 4.69 at age 3; 2.95 at ages 17-18, but

varies in between

• FCI—SEM ranges from 2.6 to 3.69– Pattern similar to MPC

Stanford Binet-5

• Good measure of general g

• SEM for Full-Scale intelligence scores range from 2.12 to 2.6

• Appears to be more stable than overall intelligence scores from other measures

Tests NOT to use• Leiter International Performance Scale-

Revised– Manual specifically states it is a measure of

nonverbal intelligence & should not be used in MR identification because it does not measure overall intelligence

• Universal Nonverbal Intelligence Test (UNIT)—also measures only nonverbal

General Guidelines for Intelligence Tests

• If scores fall below 70, clearly MR

• Between 70-75, use professional judgment– Be very careful using any score above SEM given

in technical manual of instrument

Adaptive Behavior

Adaptive Behavior Measures• Vineland—initially Vineland Social Maturity

Scale; first to measure adaptive behavior– Communication– Daily Living Skills– Socialization– Motor Skills (if under 6 years old)– Adaptive Behavior Composite

• SEM? Susceptible to Flynn effect

AAMR Adaptive Behavior Scale-School: 2nd Edition Domains

– Independent Functioning

– Physical Development

– Economic Activity– Language

Development

– Numbers & Time– Prevocational/

Vocational Activity– Self-Direction– Responsibility– Socialization

Other Adaptive Behavior Measures• Scales of Independent Behavior-Revised

– Motor Skills– Social Interaction & Communication Skills– Personal Living Skills– Community Living Skills

• Adaptive Behavior Assessment System-2nd Edition– Conceptual– Social– Practical

Problems• No adaptive behavior measure has domain

scores for all 10 of the adaptive behavior areas included in AAIDD/Texas/IDEA definition of MR

• Some areas seem to overlap & repeat• How to measure all 10? Should we try?• How will next wave of adaptive behavior

measures address 10 areas?

Conclusions/Recommendations• Be aware of Flynn effect & SEM,

especially when interpreting scores in borderline range

• Use professional judgment evaluating pre-school students and high school students with intelligence scores in borderline range– Back up decisions with history of previous

scores & eligibilities