Extremes of Intelligence
Even though intelligence tests remain in wide use, reliance on such quantitative measures has been criticized for potential cultural bias and for an overemphasis on equating intelligence with testing. It is thought that relying on IQ to define intelligence supports a narrow view, and we should instead be expanding the conversation (Schlinger, 2012; Wicherts & Dolan, 2010). In addition, researchers have noticed that the IQ scores of the world population seem to be increasing over time. This is called the Flynn effect, named after the first researcher who noticed this puzzling phenomenon (Flynn, 1987, 2012; Flynn & Weiss, 2007). No one is sure why this is happening, but explanations include that changes in education, nutrition, and physical demands have resulted in people actually being smarter now, compared to people in past generations (Flynn, 2009; Zelinski & Kennison, 2007). The Flynn effect complicates the use of psychometrics in intelligence. Despite the criticism, what continues to make the idea of IQ popular is that scores seem to predict real-world capabilities like academic and job suc- cess. As measured by traditional tests, IQ remains significantly correlated to dozens of aca- demic subjects and remains relatively stable across the lifespan (Deary, Strand, Smith, & Fer- nandes, 2007; Deary, Whiteman, Starr, Whalley, & Fox, 2004).
9.3 Extremes of Intelligence By definition, extremes of intelligence are those scores that occupy the two tails of the nor- mal distribution in Figure 9.2. At the lower end are individuals with intellectual disability
Section Review Explain the origins of our current methods of measuring intelligence.
Figure 9.2: Normal curve for intelligence
Human traits are assumed to follow the pattern of the normal curve. The distribution of IQ scores is a common example of this pattern. In a normal distribution, it is assumed that there are similar percentages (14%) of scores between 115 and 130 and between 85 and 70. Additionally, an IQ of 130 is just as rare as an IQ of 70; both are two standard deviations away from the mean of 100.
N u
m b
e r
o f
c a s e s
Scores on IQ test 55 70 85 100 115 130 145 Standard Deviation -3 -2 -1 0 +1 +2 +3
0.13%
2.15% 2.15%
13.59% 13.59%
34.13% 34.13%
percent of cases under the normal curve
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Section 9.3 Extremes of Intelligence
(formerly referred to as mental retardation), who test at 70 or less, or two standard devia- tions below the mean on an IQ test. On the other end of the spectrum are people who are considered gifted, with an IQ of 130 or above. Sometimes, however, definitions at both intel- lectual extremes vary, as we see in this section.
Intellectual Disability An intellectual disability is no longer thought of as simply having a low IQ. The contemporary perspective takes into account functional impairments in adaptive living, including areas of communication, social skills, and daily hygiene (American Psychiatric Associ- ation, 2013; Schalock et al., 2007). The most common genetic or inherited fac- tors in intellectual disability are Down syndrome (Trisomy 21) and Fragile X syndrome (see Chapter 3), though many other genetic or chromosomal abnormalities can have a profound negative effect on intellectual function- ing. Prenatal causes include fetal alco- hol spectrum disorders, the mother’s substance abuse, poor healthcare and maternal nutrition, and exposure to viruses and other teratogens (see Chapter 3). Perinatal (birth) causes include complications of low birth weight (e.g., reduced lung capacity and oxygen flow) and trauma that results in brain damage. Intellectual disabilities due to postnatal causes are more common in poorer countries, where malnutrition can significantly affect brain development and catastrophic infections can destroy established brain tissue. Still, up to half of cases are of unknown origin (Daily, Ardinger, & Holmes, 2000; McDowell & Craven, 2011).
About 85% of cases are classified as mild intellectual disability (American Psychiatric Asso- ciation, 2013). People in this category may not have been identified until after they began for- mal education. Deficits in adaptive behavior may or may not be evident to nonprofessionals, though there is likely to be some impairment of independent activities. As an adult, someone with an IQ of 65 may be quite able to socialize appropriately, live independently, do many kinds of work, get married, read enough to use basic computer processes, and order from a menu. In the less developed world, where children may begin working at an early age and formal education is limited, mild cognitive impairment may not be nearly as restrictive as it is in high-income countries.
Moderate Intellectual Disability Most individuals with Down syndrome fall into the category of moderate intellectual dis- ability, with an IQ of 40 to 55. Typically there is a high incidence of physical health problems as well, like heart defects and thyroid diseases, and increased prevalence of mental health dis- orders that impact lifestyle. Together, these effects substantially shorten lifespans (Crocker,
Robin Bartholick/Blend Images/Superstock
Down syndrome is one of the most common generic factors related to intellectual disability.
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Prokić, Morin, & Reyes, 2014; Van Schrojenstein Lantman-de Valk & Walsh, 2008). Speech delays among this group are particularly noticeable in early childhood, and individuals need considerable help with self-care and community activities. Educational potential is quite lim- ited for those with moderate intellectual disability. Schooling usually focuses on health and safety issues and daily skills, including navigating the neighborhood. With practice, many of these individuals can learn to travel independently to controlled work or volunteer facilities, but still need moderate supervision throughout their lifetimes.
Severe and Profound Intellectual Disability People with an IQ of 26 to 40 have a severe intellectual disability. Many develop speech and can feed themselves, but they do not ordinarily prepare their own meals and need help with everyday necessities and routines. Those with this condition need nearly constant supervision their entire lives. Individuals with an IQ of 25 or below have a profound intellectual disabil- ity. Nearly always there is great difficulty with mobility and communication. A less-restrictive community model that makes use of neighborhood group homes for those with severe and profound intellectual disabilities is gradually replacing the old model of institutionalization.
Educating Children With Special Needs Regardless of the extent of their disabilities, all children are entitled to be educated in the least restrictive environment, a placement that is as similar as possible to a classroom of children who do not have disabilities. The expectation is for children with special needs to become as “typical” as possible. The requirement of a placement in the least restrictive envi- ronment has led to an increase in inclusion, which means students are placed in a standard classroom for all or most of the school day. Advocates of full inclusion maintain that all chil- dren, regardless of special physical, emotional, or cognitive needs, are best served when they can regularly interact with typical peer models. The push toward a more inclusive environ- ment may be one reason that the number of children served in special education has been dropping steadily since 2004 (see Figure 9.3). It is also possible that schools (in an effort to save money), or parents of children with special needs (in the hopeful expectation to optimize learning), are electing to keep children in regular classrooms. An alternative to inclusion is mainstreaming, in which children with special needs are placed in a regular classroom for only part of a day, such as the period reserved for math.
In each of the various learning environments, the expectation is for children with special needs to be given more individual instruction geared toward their developmental needs. By being assigned work that is consistent with ability rather than age or grade level, children are more likely to make progress. For example, most special education teachers use a phonics approach to reading; intensive repetition and flash cards are helpful for those with specific math disabilities; and special paper is used for children who have difficulty staying within lines when writing.