Problem #1: Context and Learning Disabilities
Most people know that gifted children and learning disabled children can engage in behavior that looks very similar. It seems logical to say that in gifted children, this behavior occurs only in a few settings (e.g., a rigid school environment) or under only certain conditions (e.g., boredom), while in children with learning disabilities, it must occur in all settings or conditions . After all, the assumption goes, learning/developmental disabilities are a genetically-based brain problem, and a person's genetics persist no matter what environment a child experiences. Unfortunately, these assumptions, however logical, are incorrect.
First, the diagnostic bible, the DSM-IV, does not diagnose brain problems. Instead, it consists of a checklist of behaviors, which can occur for a variety of reasons. In other words, a child who has a certain number of attention and hyperactivity problems that exist in a variety of settings, are abnormal for their age, and interfere with their quality of life has ADHD, regardless of why they are inattentive and hyperactive. If a child has the requisite social and communication difficulties and rigid, repetitive behavior, they have an autism spectrum disorder, regardless of the ultimate brain basis for these symptoms. If it seems strange that the DSM-IV does not actually identify brain differences that cause the behavior, consider the variety of explanations put forth for ADHD alone, all of which are compatible with the DSM traits--poor executive function; low arousal and need for stimulation; poor inhibition; aversion to delays; and abnormal reward processing, to name a few.
Second, there is no such thing as a purely biological disability. True, dyslexia, ADHD, and autism spectrum disorder are heritable; you are more likely to have them if a family member does, too. However, like most human traits, their severity and manifestations are shaped by the environment. This includes both the physical environment (nutrition, environmental pollutants, parental drug use, etc.) and the social environment (e.g., parenting style). Many theories of ADHD and autism spectrum disorder explicitly propose models for how such environmental forces interact with biological predispositions.
Context matters for disabilities, too. Thus, one should not say, for example, "my child has difficulty paying attention primarily when they're bored or uninterested in a task; therefore, they can't have ADHD." Every human being on earth has more difficulty paying attention when bored , and those with ADHD are affected even more by this situation than the average person [3, 4]. People with ADHD are not necessarily different in how they control their attention when they're interested . In fact, they can maintain a state of "hyperfocus" (deep concentration and absorption, tuning out the rest of the world) for hours at a time in a way typically developing people rarely do [5, 6]. (While writers on twice exceptionality often claim that people with ADHD cannot focus even when interested , this is a myth no longer believed by ADHD researchers). What makes people with ADHD different is how much their performance suffers when bored. That is when their difficulties controlling their attention really come to the fore.
Similarly, it is not enough to know that an undemanding school environment leads a child to pay poor attention or behave hyperactively. Undemanding school environments don't inspire children with ADHD, either.
So how does one tell whether a gifted child also has learning disabilities? The difference is a matter of degree rather than kind. How much of a problem do the inattention and hyperactivity cause? How much control does the child have over them? To what extent do they persist after the school environment improves?
Problem 2. Misunderstandings caused by an external perspective on disabilities
Another misconception is that when the same behavior occurs in gifted people and people with disabilities, it must occur for different reasons. These writers seem to understand the reasons for gifted children's problem behavior rather well, but many researchers and most people with the disability in question would dispute their characterization of disabled people's reasoning.
For example, some argue that gifted people direct their energy towards goals, while people with ADHD expend theirs randomly and purposelessly (e.g., [7, 8]). Purpose, however, is in the eyes of the beholder. A child who wanders around the classroom for several minutes without engaging in any other activity may seem aimless to an observer. However, their pacing may fulfill purposes such as stress relief, burning off nervous energy, or taking a "brain break." People with ADHD can switch from activity to activity too often to make progress on any single task, and this does interfere with productivity. However, they behave this way for a reason: they get caught up in new ideas. Due to poor working memory, they forget things quickly, so they seek to pursue the new idea before they forget it . Meanwhile, due to these same working memory difficulties, they forget about the old task. Similarly, the odd, repetitive movements and noises autistic children make also serves a purpose. They may be self-calming, or produce pleasurable sensory input, or help them make sense of a world they find difficult to understand. In short, one cannot say that people with disabilities behave purposely while gifted people act with purpose. This would be unfair and dehumanizing to disabled people as well as inaccurate.
Autistic people do not interact reciprocally with other people, but this does not mean they lack interest in other people. Rather, they have difficulty reading social cues and producing the sorts of behaviors typically developing people demand from social interactions . Many autistic people want friends, although they may have no idea how to make them, and feel deeply depressed by their social isolation . Autistic people cannot read body language indicating that they are boring others, and they may not learn on their own how to ask others questions or take turns in a conversation. While autistic people often have no idea that their loved ones feel bad until being told, once clearly and explicitly informed, they suffer along with their loved ones . They may then express their caring in the wrong way, by trying to solve the problem that caused the loved one's pain instead of by listening and verbaly expressing their concern. Again, they must learn the skill of listening in a visibly empathetic way. In short, one cannot say, as some researchers do , that a gifted person cannot be autistic if they are interested in other people, want friends, or feel compassion for others. Such assumptions are not only factually inaccurate but dehumanizing to autistic people [14, 15]. (One can, however, say that a gifted person who excels at social interaction, at least with mental age peers, cannot be autistic, since autism by definition involves a deficit in social behavior).
People with disabilities often act for the same reasons as gifted people. For example, many people with autism, like gifted children, feel isolated because they lack peers who share common interests. Like gifted children, people with autism may relate poorly to others due to social anxiety and concern over how others perceive them. Using biological measures of stress (salivary cortisol), Corbett & her colleagues  confirmed that autistic people experience extreme social anxiety from even nonthreatening, noncoercive social interactions--free play on a playground. This anxiety increases as children get over, and probably interferes further with their ability to interact. The social anxiety of a gifted child does not hold a candle to the crippling social anxiety of the average autistic child.
Autistic people do not lie or even seem to understand lying, and they increase their unpopularity by teaching and correcting classmates who do not wish to be instructed . One reason is that, like gifted people, they have strong principles of honesty and truthfulness which can be overly black and white . This has been described as a "systematizing" approach to morality, but a better term would probably be "principled."
Not only do people with disabilities act for the same reasons as gifted people; gifted people may act for the same reasons as people with disabilities. In some respects, gifted children may share the naivete of autistic children. For example, both have been described as not understanding why anyone would want to lie. Furthermore, as with autistic children, some researchers believe "it makes no sense" to them "that other children might not want to be shown the best way to do something, or might prefer to do things the way they always have, even if it is not very fair" .
In short, researchers who think we can draw a clean distinction between learning disabilities and giftedness based on motivation often misunderstand the motivations of disabled people due to an external perspective. I think we would be better off pointing to differences in observable behavior.
3. Misunderstandings about the identification of twice-exceptional students
Research on learning and developmental disabilities makes clear that subtest analysis--the practice of making clinical decisions based on "scatter" or huge gaps between IQ subtests--is ineffective and clinically unsound . Unfortunately, the gifted education field seems unfamiliar with this research, and many champion the use of scatter to identify twice-exceptional children .
Subtest analysis is statistically unreliable because individual subtests are less reliable than the test as a whole. In other words, if we tested the child on a different day or under different conditions, it's unclear whether we would find the same profile of strengths and weaknesses (or if that profile would still be different enough from the norm to be significant). The standard reliability coefficient for making educational classification decisions is .90 or above, but very few individual subtests have reliability coefficients this high .
Furthermore, while certain profiles are more common in learning disabilities than in the typically developing population, the inverse simply isn't true. One can have these profiles without having the learning disability. For example, dyslexics generally have higher performance IQ than verbal IQ, and those with Nonverbal Learning Disability have higher verbal than performance IQ. However, a person with higher performance IQ need not be dyslexic, and a person with higher verbal IQ may not have a Nonverbal Learning Disability.
Some disorders do not even have such a consistent pattern. While most people with Aspergers have a significant verbal-performance gap, 48% are verbally skewed and 18% are performance skewed, a smaller but not negligible percentage . Profiles also differ across learning disabilities, such that, there is no single "twice exceptional profile" .
Scatter does not necessarily imply learning disabilities because it is extremely common in the gifted population [23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52]. The correlation between subtests decreases as IQ increases [53, 54, 41]. Verbal and performance scores can differ by over 13 points in 69%, by over 18 points in 55%, and by 25 or more in 27%. Indeed, a gifted child is five times as likely as the standardization sample would predict to have a verbal-performance gap of 25 or more points (close to 2 standard deviations) . Only 39 or 40% of gifted children have a "flat" profile of scores, with no major gaps between subtests .
Differences are even more extreme when comparing verbal or performance strengths to working memory or processing speed weaknesses. Nearly 60% of children at the Gifted Development Center had verbal-processing speed gaps of 23 points, and discrepancies ranged as high as 69 points (over 4 standard deviations) . Thus, if we assume that all gifted children with wide subtest scatter have learning disabilities, over half of gifted children would be considered twice exceptional--an unlikely state of affairs.
In the same way, specific patterns of scatter considered diagnostic of learning disabilities often occur in the gifted population. Neilsen (2002) found that learning disabled gifted students have relative weaknesses on two IQ subtests: Coding, which measures processing speed, and Digit Span, which measures working memory . However, studies of the general gifted population finds similar weaknesses [29, 31, 32, 59, 33, 59, 60, 61, 41, 62, 42, 63, 64, 52]. Again, one cannot assume a child with relative weaknesses in coding, digit span, or arithmetic has learning disabilities, as this would make most of the gifted population twice exceptional.
This is not to say scatter is unimportant or that we should ignore it. People with gaps of 2 or more standard deviations between their highest and lowest IQ scores need not have learning disabilities, but they may still have difficulties. Scatter is an index of uneven development, and people whose working memory or processing speed cannot keep pace with their reasoning do indeed have difficulties producing what they conceive, a frustrating situation. Thus, scatter is a potential red flag for intervention. However, if a person does not suffer distress, and if their cognitive weaknesses do not prevent them from taking advantage of learning opportunities they need (e.g., gifted programs or desired careers), why give them a stigmatizing label?
Starred references are references I think are particularly good, well-reasoned, and informative.
1. Webb, James T., Amend, Edward R., Webb, Nadia E., Goerss, Jean, Beljan, Paul, Olenchak, F. Richard (2004). Misdiagnosis & dual diagnosis of gifted children. Abstracted from: Misdiagnosis & dual diagnoses of gifted children & adults: ADHD, bipolar, OCD, Asperger’s depression, & other disorders (2004). Scottsdale: Great Potential Press.
2. *Mika, Elizabeth (2006). Giftedness, ADHD, and overexcitabilities: The possibilities of misinformation. Roeper Review 28:4, 237-242.
3. Barkley, Russell A. (1990). Attention deficit hyperactivity disorder: A handbook for diagnosis and treatment. Guilford Press: New York.
4. Luk, S. (1985). --> Direct observation studies of hyperactive behaviors. Journal of the American Academy of Child Psychiatry, 24, 338- 344 5. Kalfbleisch & Castellanos nd
6. Hallowell & Ratey 1994
7. --> Webb, James T. & Latimer, Diane (1993). ADHD and children who are gifted. An ERIC Digest from the ERIC Clearinghouse on Disabilities and Gifted Education 8. Hartnett, D. Niall, Nelson, Jason Nelson., & Rinn, Anne N. (2004). Gifted or ADHD? The possibilities of misdiagnosis. Roeper Review 26, 73-76.
9. Hallowell, Edward M. (1992). What's it like to have ADHD?
10. --> Terra, Cary (2012). Asperger’s in adults & empathy. Autism & Empathy http://www.autismandempathy.com/?p=1418 6/25/12 11. Yale Child Study Center nd
12. Dziobek & Rogers 2004
13. -->Amend, Edward R. (2003). Counseling, Multiple Exceptionality, and Psychological Issues. SENG 14. Gernsbacher 2007
15. --> Cohen-Rottenberg, Rachel (2011). On the matter of empathy. Autismandempathy.com, 6/27/11. 16. Corbett et al 2010
17. --> Attwood T (2007). The Complete Guide to Asperger's Syndrome. Jessica Kingsley Publishers, London
18. --> Carley, Michael John (2008). Asperger’s from the inside out. NY: Perigee
19. --> Lovecky, D. V. (1992). Exploring social and emotional aspects of giftedness in children, Roeper Review, Vol. 15 Issue 1,18
20. Lovett, Benjamin J. & Lewandowski, Lawrence J. (2006). Gifted students with learning disabilities: Who are they? Journal of Learning Disabilities 39:6, 515-527
21. Silverman 2011
22. --> Hippler, Kathrin & Klicpera, Christian (2004). A retrospective analysis of the clinical case records of ‘autistic psychopaths’ diagnosed by Hans Asperger and his team at the University Children’s Hospital, Vienna. In Frith, U. & Hill, E. (eds). Autism: Mind & Brain. Oxford: Oxford University Press.
23. Achter, Benbow & Lubinski 1997
24. Barton, J.M. & Starnes, W.T. (1989). Identifying distinguishing characteristics of gifted and talented/learning disabled students. Roeper Review 12, 23-29.
25. Beal 1995
26. Beal 1996
27. Berninger et al 1993
28. Bliesmer 1954
29. Brown & Yakimowski 1987
30. Cameron et al 1997
31. -->Falk, R. F., Silverman, L K., & Moran, D. (2004, November). Using two WISC-IV
indices to identify the gifted. Paper presented at the 51st Annual Convention of the National Association for Gifted Children, Salt Lake City, UT33. Hollinger & Kosek 1986
32. Fishkin & Kampsnider 1996
32. Fishkin & Kampsnider 1996
34. Kaufman 1979
35. Keating 1991
36. Kennedy et al 1963
37. Kline et al 1993
38. Lohman 2005
39. Malone et al 1991
40. Mueller et al 1984
41. --> Patchett, Robin R., & Stansfield, Michael (1992). Subtest scatter on the WISC-R with children of superior intelligence. Psychology in the Schools 29:1, 5-11
42. Ricci 1998
43. Rimm, Gilman & Silverman 2008
44. --> Silver, Stephen J., & Clampit, Michael K. (1990). WISC-R profiles of high ability children: interpretation of verbal-performance discrepancies. Gifted Child Quarterly 34:2 76-79
45. Silverman 1995
46. Silverman 2007- --> Silverman, Linda (2007). What we have learned about gifted children 1979-2007.
47. Speer et al 1986
48. Webb 1992
49. Webb 2000
50. Webb & Dyer 1993
51. Webb & Kleine 1993
52. --> Wilkinson, S. Cynthia (1993). WISC-R profiles of children with superior intellectual ability. Gifted Child Quarterly 37:2, 84-91
53. Detterman, Douglas K. & Daniel, Mark H. (1989). Correlations of mental tests with each other and with cognitive variables are highest for low IQ groups. Intelligence 13, 349-359.
54. --> Gyurke, James S., Prifitera, Aurelio & Sharp, Stephanie A. (1991). The frequency of verbal and performance IQ discrepancies on the WPPSI-R at various levels of ability. Journal of Psychoeducational Assessment 9, 230-239
55. --> Sweetland, John D., Reina, Jacqueline M., & Tatti, Anne F. (2006). WISC-III verbal/performance discrepancies among a sample of gifted children. Gifted Child Quarterly 50:7, 7-10 56. --> Lohman, David F., Gambrell, James & Lakin, Joni (2008). The commonality of extreme discrepancies in the ability profiles of academically gifted students. Psych. Science Quarterly 50:2, 269-282.
57. Silverman, Gilman & Falk nd
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--> Silverman, Linda (2009). The measurement of giftedness. In Shavinina, L.V. (ed), International Handbook on Giftedness 65. Wechsler 2003