Can a mild MR/ID person fail to be formally diagnosed before the age of 18? Do Forrest Gump's exist?

The third prong of MR/ID identification in Atkins hearings is the need for MR/ID to be diagnosed before the age of 18. There are a number of potential problems with implementing this part of the MR/ID definition.

The question should be asked: "Is it possible for someone who is mild MR (e.g., IQ=70) to NOT be identified as MR/ID while they are in school?"

The answer is "yes." One cannot assume that the lack of MR/ID identification or special educations services during a person's formative school years (up to age 18) means they were not eligible for those services at the time. How can this be?

First, in most cases, even if a formal diagnosis and placement in special education did not occur, typically the school records of many Atkins defendants frequently show that many of these individuals have a long history of poor academic performance, retention in grade, etc. Also, I was a school psychologist from 1975-1989 and vividly remember  the "games" school psychologists and school systems often played re "dodge the MR diagnosis" when possible. School psychologists and special educators are a caring group and would much prefer to minimize a parents pain (when hearing the results of special education and psychological testing) by labeling a student as "learning disabled" (LD) rather than "mentally retarded" (MR). Gresham (2009) captures the reality of intellectual testing and diagnosis in the mid 1970's to 1980's when he stated:

It is well-established that schools were and are reluctant to classify children as mentally retarded, particularly African-American students since the 1970s (MacMillan & Siperstein, 2002). Schools frequently assign a more ‘‘palatable’’ label to students who would otherwise be classified as mentally retarded, using labels such as ‘‘specific learning disability’’ or ‘‘speech and language impairment.’’ In Atkins cases, this frequently works against the defense’s efforts because there is no developmental history of an individual ever being diagnosed as mentally retarded, thereby making it difficult to prove the developmental criterion of mental retardation.(p.9).

Gresham, F. M. (2009).  Interpretation of Intelligence Test Scores in Atkins Cases:  Conceptual and Psychometric Issues.  Applied Neuropsychology, 16, 91-97

Second, there has been a long-held (mistaken) assumption, both in the lay public and with many professionals who do intelligence testing, that a person's IQ score sets a limit on their academic learning.  That is, because of their limited intellectual ability (IQ), one cannot expect these individuals to achieve at levels above their measured IQ.  This is a false assumption.

For any given level of IQ scores, there is a normal distribution of achievement around that level of intelligence.  Half of the population with a specific IQ score will score at or below that IQ score (what many people assume to be correct), but half of the population with that IQ will score above that IQ score...and some by a large amount (what many people fail to recognize and understand).

I previously wrote about this, and provided the statistical explanation plus real-world data (using IQ and achievement data from the WJ III Battery).  That material was written for a policy paper, but the guts of the message and the data make it clear that it is possible for someone with a measured of IQ of 70 to be achieving above their measured intelligence, often into the lower or middle levels of the average range.  I've extracted the relevant portion of the specific NCEO policy report and am making it available here (click here---click here for the complete report).  Additionally, an on-line PPT slideshow is available that presents this information in a very understandable format (click here for "Forrest Gump" presentation).  I would urge readers to review those materials before reading further..............................................................................................................................................

Assuming you have followed my directions, you now know that it is just as likely for a student with an IQ of 70 to be achieving above their tested intelligence as it is to be achieving below their level of tested intelligence.  Why is this important for the third prong of Atkins decisions?

This is important because (and if folks want some references and articles I'll dig them up...it was research done in the mid to late 1970's) it is known that there are "gatekeeping" characteristics of students that increase the probability they will be referred to special education for assessment.  Typically these are low achievement , behavior problems, ADHD, etc..  Thus, many school special education and school psychology personal end up seeing those students with mild MR (in this example IQ=70) who are a biased sample of the complete population of students with the same level of intelligence.  Those who are not achieving satisfactorily or who dispaly behavior problems, are likely to be referred.  Those who sit still, listen, attend, don't bother others, and who demonstrate achievement at levels that a classroom teacher can manage, are typically not referred.  These later students, some who may have an IQ of 70, go unnoticed and undiagnosed as they progress through the school system.  As demonstrated in the reports and slideshows, a decent number of these students will demonstrate achievement levels above that often expected for a person with an IQ of 70...often into the range considered low average or average for a grade.  They may have the same level of cognitive abilities, but are not identified or referred for testing and classification because of their decent achievement and good behavior.

Bottom line.  It is possible for an individual in the upper end of the mild MR/ID ranges to NOT be referred for special education testing and/or services, even though their level of measured of intelligence might make them eligible for "MR/ID" services.  The absence of placement in an MR/ID program (and the lack of IQ testing) during an individuals school career does not preclude the possibility that they may have meet the magical IQ score for services ONLY if they had been referred.  The occurrence of IQ testing and special education services during an individuals formative years of life (up to age 18) does NOT mean that they can not be diagnosed MR/ID later in life.

Of course, there are all kinds of caveats and special "what ifs" that I could address.  One would be the need to look at the distribution of achievement scores for individuals with mild MR IQs and concurrent measured deficits in adaptive behavior (as per a standardized adaptive behavior scale)....do they show the same achievement distribution (above and below the measured IQ) as presented in the above materials?  This is an empirical question.  One needs data on samples where subjects have scores from IQ, achievement, and adaptive behavior measures to answer this question empirically.  I may have some such data sets in my files and plan to locate them and see if they have sufficient sample sizes and measures to evaluate this question.

It is possible for a person to NOT be identified as MR/ID before the age of 18.  Identification before the age of 18 is a complex interplay of individual characteristics of the person and characteristics of the school social system and social-political policies in-place at the time.


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