Chapter 9
Mental Retardation
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Intelligence and Mental Retardation
 Prior to mid-19th century, mentally retarded were ignored or feared
even by the medical profession
 Intellectual disability: significant limitations in intellectual functioning
and adaptive behavior that begin before age 18
 Pertains to limitations in intellectual functioning/adaptive behavior
 Historically, prevailing attitudes have been scorn and rejection
 Discovery of feral children and expansion of humanitarian efforts
helped end misunderstanding/mistreatment of mentally retarded
 In mid-19th century Samuel G. Howe opened the first humanitarian
institution to educate the “feebleminded”
 By 1940s parents began to work for humane care of their children
 1950: National Association for Retarded Chidren
 1962: President John F. Kennedy formed the President’s Panel on
Mental Retardation calling for national program to combat mental
retardation
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Intelligence and Mental Retardation (cont.)
 The Eugenics Scare
 Eugenics: the science dealing with all influences that improve the
inborn qualities of a race
 Evolutionary degeneracy theory
 pervasive in 19th century
 viewed intellectual/social problems of mentally retarded as
regression to earlier period in human evolution (“missing
link”)
 J. Langdon H. Down: viewed “strange anomalies” as
throwbacks to Mongol race
 The eugenics movement, first defined by Sir Francis Galton in
1883, led to the view that individuals with MR (moral imbeciles,
or morons) were threats to society
 G. Stanley Hall: children 8-12 are “mature savages” who need
strong social forces to become civilized
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Intelligence and Mental Retardation (cont.)
 Purpose of IQ Tests
 Used to identify school children who might need special help in
school
 Defining and Measuring Children’s Intelligence and Adaptive
Behavior
 Alfred Binet and Theophile Simon were commissioned by
French government to develop the first intelligence tests to
measure judgment and reasoning of school children
 General intellectual functioning is now defined by an
intelligence quotient (IQ or equivalent) based on standardized
assessments
 MR is not defined solely on the basis of IQ; one’s level of
adaptive functioning is important
 Adaptive functioning: how effectively individuals cope with
ordinary life demands and how capable they are of living
independently and abiding by community standards
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Intelligence and Mental Retardation (cont.)
 The Controversial IQ
 IQ is relatively stable over time, except when measured in
young, normally-developing infants
 Mental ability is always modified by experience
 early stimulation programs help children build on their
existing strengths
 Are We Really Getting Smarter?
 The Flynn Effect refers to the phenomenon that IQ scores
have risen about 3 points per decade since IQ testing
began
 Are IQ Tests Biased or Unfair?
 African Americans score about 1 SD below whites
 Likely due to economic and social inequality
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Features of Intellectual Retardation
 Clinical Description
 Considerable range of abilities and interpersonal qualities
 DSM-IV-TR Diagnostic criteria
 significantly subaverage IQ (<70)
 concurrent deficits or impairments in adaptive
functioning
 below-average intellectual and adaptive abilities must
be evident prior to age 18
 Criteria are arbitrary; a label of MR has serious
ramifications, including placement in school learning
environment
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Features of Intellectual Disabilities (cont.)
 Degrees of Impairment
 Mild MR (IQ of 55 to 70)
 about 85% of persons with MR
 typically not identified until elementary school years
 overrepresentation of minority group members
 develop social and communication skills; possibly moderate
delays in expressive language
 with appropriate supports, as adults they usually live
successfully in the community
 Moderate MR (IQ of 40 to 54)
 about 10% of persons with MR
 usually identified during preschool years
 applies to many people with Down syndrome
 benefit from vocational training and in adulthood can
perform supervised unskilled/semi-skilled work
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Features of Intellectual Disabilities (cont.)
 Degrees of Impairment (cont.)
 Severe MR (IQ of 25 to 39)
 about 3%-4% of persons with MR
 often associated with organic causes
 usually identified at a very young age due to delays in
developmental milestones
 between ages 13-15 their academic and adaptive
abilities are similar to an average 4-6-year-old
 may have mobility and health-related problems
 need special assistance throughout their lives; adapt
well to living in group homes or with their families
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Features of Intellectual Disabilities (cont.)
 Degrees of Impairment (cont.)
 Profound MR (IQ below 20 or 25)
 about 1%-2% of persons with MR
 usually identified in infancy due to marked delays
in development and biological anomalies
 learn only the rudiments of communication skills
and require intensive training to learn eating,
grooming, toileting, dressing behaviors
 require lifelong care and assistance
 almost always associated with organic causes and
often co-occurs with severe medical conditions
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Features of Intellectual Disabilities (cont.)
 Level of Needed Supports
 DSM-IV-TR categories criticized as stigmatizing and
limiting because they emphasize degree of impairment
 AAIDD focuses on level of support or assistance needed
(rather than on IQ):
 intermittent
 limited
 extensive
 pervasive
 Emphasis on interaction between person and
environment to determine level of functioning
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Features of Intellectual Disabilities (cont.)
 Race, Sex, and SES Prevalence
 1-3% of population (depending on cutoff)
 Twice as many males as females
 sex ratio decreased to 1.5:1.0 for those with more
severe forms
 More prevalent in lower SES and in minority groups,
especially for mild MR; no differences for more severe
levels
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Developmental Course and Adult Outcomes
 Most common cause of severe mental retardation: chromosome
abnormalities
 Down syndrome is the most common disorder resulting from
chromosome abnormalities
 Developmental vs. Difference Controversy: Whether children with
MR progress through the same developmental milestones in a
similar sequence as other children
 Similar sequence: same order, different rate/upper limit
 Similar structure: children with MR show same behaviors and
underlying processes as typically developing children at same
cognitive level
 Difference viewpoint: cognitive development of MR children is
qualitatively different in reasoning and problem-solving
strategies
 Familial versus organically based MR
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Developmental Course and Adult Outcomes (cont.)
 Motivation
 Many children with mild MR are able to learn and attend
regular schools and classrooms
 Often susceptible to feelings of helplessness and
frustration in their learning environments, causing
problems in social and cognitive development, which can
lead to low expectations and limited success
 With stimulating environments and caregiver support,
children who have mild mental retardation are able to stay
on task and develop goal-directed behavior
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Developmental Course and Adult Outcomes (cont.)
 Changes in Abilities
 IQ scores can fluctuate in relation to level of impairment
and type of retardation
 Major cause of MR affects the degree to which adaptive
abilities may change
 Slowing and stability hypothesis: IQ of children with Down
syndrome may plateau during middle childhood, then
decrease over time
 They may continue to develop in intelligence at a
progressively slower rate
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Developmental Course and Adult Outcomes (cont.)
 Language and Social Development
 Follows a predictable/organized course
 The underlying symbolic abilities of Down syndrome children
are largely intact
 Considerable delay in expressive language development in
children with Down syndrome and expressive language is
weaker than their receptive language
 Fewer signals of distress or desire for proximity with primary
caregiver, which can influence attachment
 Delayed, but positive, development of self-recognition
 Delayed and aberrant functioning in internal state language that
reflects emergent sense of self and others
 Deficits in social skills and social-cognitive ability; can lead to
rejection by peers
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Developmental Course and Adult Outcomes (cont.)
 Emotional and Behavioral Problems
 Emotional and behavioral disturbances 3 to 7 times greater
than other children, due largely to limited communication skills,
additional stressors, and neurological deficits
 Most common psychiatric diagnoses: Impulse control problems,
anxiety problems, and mood problems
 Consistent with their normally developing peers, internalizing
problems in adolescence almost twice that of younger children
 ADHD-related symptoms also common
 Pica is common for those with severe/profound MR; selfinjurious behavior (SIB), which can be life-threatening, affects
about 8% of persons across all ages/levels of retardation
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Developmental Course and Adult Outcomes (cont.)
 Other Disabilities
 Can be associated with other pervasive physical and
developmental disabilities
 12% of children with mild MR and 45% with moderate
to profound MR have at least one other disability, such
as sensory impairments, cerebral palsy, and epilepsy
 Chance of other disability increases as degree of
intellectual impairment increases
 Despite co-occurring disabilities, life expectancy for
individuals with Down syndrome is now approaching 60
years
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Causes
 Although over 1,000 genetic disorders are associated with mental
retardation, scientists cannot account for the majority of cases,
especially the milder forms
 Genetic or environmental causes are known for almost 2/3 of
individuals with moderate to profound MR and only 1/4 for mild MR
 The two-group approach:
 organic mental retardation: clear biological cause (e.g.,
chromosome abnormalities, single gene conditions, and
neurobiological influences); associated with severe and
profound MR
 cultural-familial mental retardation: associated with mild MR;
family history of mental retardation, economic deprivation,
inadequate child care, poor nutrition, and parental
psychopathology; no organic cause
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Causes (cont.)
 Inheritance and the Role of the Environment
 Genetic influences are potentially modifiable by environment
 Children do not inherit an IQ, they inherit a genotype: a
collection of genes that pertain to intelligence
 The expression of the genotype in the environment (gene x
environment interaction) is the phenotype
 Heritability describes the proportion of the variation of a trait
attributable to genetic influences in the population and can
range from 0% to 100% genetically determined
 The heritability of intelligence is approximately 50%
 Major environmental variations affect cognitive performance
and social adjustment in children from disadvantaged
backgrounds
 Prenatal influences may be mistaken for genetic when they
are actually environmental
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Causes (cont.)
 Genetic and Constitutional Factors
 Chromosome abnormalities are the most common cause of
severe MR
 The most common of these is Down syndrome, which is
usually the result of nondisjunction: failure of the 21st pair of
the mother’s chromosomes to separate during meiosis,
causing an additional chromosome (trisomy 21)
 Fragile-X syndrome, the most common cause of inherited
MR, is associated with the FMR-1 gene
 Prader-Willi and Angelman syndromes both associated with
abnormality of chromosome 15; believed to be spontaneous
genetic birth defects occurring around the time of
conception
 Single-gene conditions (inborn errors of metabolism) can
result in syndromes such as PKU, which results in lack of
liver enzymes necessary to metabolize phenylalanine; it can
be successfully treated
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Causes (cont.)
 Neurobiological influences
 Adverse biological conditions (e.g., malnutrition, exposure to
toxins, prenatal and perinatal stressors)
 Infections, traumas, and accidental poisonings during infancy
and childhood
 Fetal Alcohol Spectrum Disorder (FASD): a range of outcomes
associated with prenatal alcohol exposure
 Fetal alcohol syndrome (FAS) is the leading known cause of
mental retardation, may be as high as 10-40 per 1000 live
births (results from consuming alcohol during pregnancy)
 CNS dysfunction, facial abnormalities, growth retardation,
mild MR, attention deficits, poor impulse control, serious
behavior problems
 Other teratogens that increase risk of MR are viral infections
(e.g., rubella), syphilis, scarlet fever, degenerative nerve
diseases, X-rays, drugs, poisons (e.g., lead and carbon
monoxide)
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Causes (cont.)
 Social and Psychological Dimensions
 Least understood/most diverse factors causing MR
 Environmental influences account for 15-20% of MR:
 deprived physical and emotional care and stimulation
of the infant
 other mental disorders accompanied by MR, such as
autism
 parents are critically important--they can help their
child by adapting, using social supports and
community resources, strategies for coping with their
children’s problems and families’ level of social
support
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Prevention, Education, and Treatment
 Child’s overall adjustment is a function of parental
participation, family resources, social supports, level of
intellectual deficit, temperament, and other specific deficits
 Treatment involves a multi-component, integrated strategy
that considers children’s needs within the context of their
individual development, family and institutional setting, and
community
 Drug treatment can help in some cases when targeted at
desirable changes in specific behaviors/dimensions (e.g.,
compulsions, aggression)
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Prevention, Education, and Treatment (cont.)
 Prenatal Education and Screening
 Many debilitating forms of MR (e.g., those related to fetal
alcohol syndrome, lead poisoning, rubella) can be
prevented if precautions are taken
 Prenatal programs for parents caution about use of
alcohol, tobacco, drugs, caffeine during pregnancy
 education about childbirth and postnatal adjustment
 additional support provided
 increasing focus on cultural diversity/sensitivity
 Prenatal screening for genetic abnormalities
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Prevention, Education, Treatment (cont.)
 Psychosocial Treatments
 Early Intervention
 One of the most promising methods for enhancing the
intellectual and social skills of young children with
developmental disabilities
 Carolina Abecedarian Project provides enriched
environments from early infancy through preschool
years
 Optimal timing for intervention is during preschool
years
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Prevention, Education, Treatment (cont.)
 Psychosocial treatments (cont.)
 Behavioral Treatments
 Initially seen as a means to control/redirect negative
behaviors in institutions
 Association for Behavior Analysis (ABA): right to the
least restrictive effective treatment and right to
treatment that results in safe and meaningful behavior
change
 Training is tailored to each child and may include
shaping, modeling, graduated guidance, and social
skills training
 Cognitive-behavioral Therapy
 Self-instructional training and metacognitive training
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning
Prevention, Education, and Treatment (cont.)
 Psychosocial Treatments (cont.)
 Family-oriented strategies help families cope with the
demands of raising a child with MR
 Some children/adolescents with MR benefit from
residential care or out-of-home placement, which
has unique responsibilities for family members
 The inclusion movement integrates individuals
with disabilities into regular classroom settings
regardless of the severity of the disability
 Adapt school curriculum to meet the individual
needs and abilities of each child
 Even when children are placed outside the family,
family involvement continues to play a critical role
Mash/Wolfe Abnormal Child Psychology, 4th edition
© 2009 Cengage Learning